CN115529746A - Hole metal process for high-aspect-ratio blind hole of circuit board - Google Patents
Hole metal process for high-aspect-ratio blind hole of circuit board Download PDFInfo
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- CN115529746A CN115529746A CN202211193367.0A CN202211193367A CN115529746A CN 115529746 A CN115529746 A CN 115529746A CN 202211193367 A CN202211193367 A CN 202211193367A CN 115529746 A CN115529746 A CN 115529746A
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
- H05K3/42—Plated through-holes or plated via connections
- H05K3/425—Plated through-holes or plated via connections characterised by the sequence of steps for plating the through-holes or via connections in relation to the conductive pattern
- H05K3/427—Plated through-holes or plated via connections characterised by the sequence of steps for plating the through-holes or via connections in relation to the conductive pattern initial plating of through-holes in metal-clad substrates
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/22—Secondary treatment of printed circuits
- H05K3/225—Correcting or repairing of printed circuits
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/22—Secondary treatment of printed circuits
- H05K3/227—Drying of printed circuits
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
- H05K3/42—Plated through-holes or plated via connections
- H05K3/421—Blind plated via connections
Abstract
The application provides a hole metal process of a circuit board high aspect ratio blind hole. The hole metal process of the high aspect ratio blind hole of the circuit board comprises the following steps: obtaining a nano graphite hole metallization solution and a circuit board to be processed; cleaning and hole-trimming operation is carried out on the circuit board to be processed; carrying out graphite adsorption operation on the pretreated circuit board by adopting a nano graphite hole metallization solution so as to form a nano graphite layer on the hole wall and the hole bottom of the blind hole of the pretreated circuit board; performing fixation treatment on the pretreatment circuit board after the graphite adsorption treatment to remove partial nano graphite on the surface of the nano graphite layer in the blind hole of the pretreatment circuit board; drying the semi-finished circuit board; and carrying out micro-etching electroplating operation on the dried circuit board semi-finished product to obtain the direct electroplating circuit board. The hole metal process for the circuit board with the high-aspect-ratio blind hole can better ensure the conduction effect of the blind hole, and further ensure that each layer of the circuit board has a better conduction effect.
Description
Technical Field
The invention relates to the technical field of circuit board processing, in particular to a hole metal process of a circuit board high aspect ratio blind hole.
Background
The existing mature circuit board hole metallization process is a chemical copper deposition process, the general flow of the chemical copper deposition process comprises feeding, cleaning and hole finishing, washing, micro-etching, washing, presoaking, activating, washing, accelerating, washing, copper-dissolving, washing and discharging, blind holes with ultra high Aspect Ratio (AR) can be met in the circuit board production and manufacturing process due to the design requirements of end products, the conventional blind holes AR is less than or equal to 0.8, the deep blind holes AR is more than 0.8, if the chemical copper deposition process is adopted to carry out hole metallization on the blind holes with the high Aspect Ratio, a large amount of hydrogen can be generated in the process due to the metal oxidation-reduction reaction in the chemical copper deposition process, air stirring is needed in a chemical copper groove to assist in maintaining the stability of liquid medicine, and the deep blind holes with the high Aspect Ratio are relatively deep or relatively small in diameter, so that the existing hydrogen and air can enter the blind holes and be sufficiently discharged, and the exchange of the liquid medicine in the chemical copper groove can not be effectively deposited in the deep blind holes.
The chemical copper deposition reaction equation is as follows:
that is to say, a chemical copper deposition process is adopted to perform hole metallization on the blind hole with a high aspect ratio, and particularly when the aspect ratio AR of the blind hole is as high as 2, copper is difficult to deposit in the deep part of the blind hole, so that the copper layer is difficult to be electroplated and thickened on the part where the copper is not deposited in the subsequent copper plating process, and further the blind hole is poor in conduction, so that the situation of poor conduction among all layers of the circuit board is easy to occur, and the use of the circuit board is influenced;
currently, a direct electroplating process is mostly adopted to achieve hole metallization of a blind hole with a high aspect ratio, for example, patent CN110351956a, specifically, graphene oxide hole metallization liquid is adsorbed on a hole wall and a hole bottom of the blind hole to form a conductive layer, and then the hole metallization of the blind hole is completed by electroplating on the basis of the conductive layer.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provides a hole metal process of a circuit board with a high-aspect-ratio blind hole, which can better ensure the conduction effect of the blind hole and further ensure the better conduction effect among layers of the circuit board.
The purpose of the invention is realized by the following technical scheme:
a hole metal process of a circuit board high aspect ratio blind hole comprises the following steps:
obtaining a nano graphite hole metallization solution and a circuit board to be processed;
cleaning and hole-trimming the circuit board to be processed to obtain a pre-processed circuit board;
performing graphite adsorption operation on the pretreated circuit board by using the nano graphite hole metallization solution so as to form a nano graphite layer on the hole wall and the hole bottom of the blind hole of the pretreated circuit board;
performing fixation treatment on the pre-treated circuit board subjected to graphite adsorption treatment to remove partial nano graphite on the surface of the nano graphite layer in the blind hole of the pre-treated circuit board to obtain a circuit board semi-finished product;
drying the semi-finished circuit board;
and carrying out micro-etching electroplating operation on the dried circuit board semi-finished product to obtain the direct electroplating circuit board.
In one embodiment, the cleaning and hole-trimming operation performed on the circuit board to be processed specifically includes: and cleaning the blind holes of the circuit board to be processed by adopting a mixed solution of polyethylene glycol and hydroxyethyl ethylenediamine, and adjusting the blind holes until the hole walls are positively charged.
In one embodiment, the graphite adsorption operation is carried out on the pretreated circuit board by using the nano graphite hole metallization solution under the ultrasonic vibration condition.
In one embodiment, the nano-graphite pore metallization solution comprises nano-graphite, a binder, a dispersant, a surface energizer, and a basic buffer salt.
In one embodiment, the fixing treatment of the pre-treated circuit board after the graphite adsorption treatment is specifically to soak the pre-treated circuit board after the graphite adsorption treatment by using a sulfuric acid solution.
In one embodiment, the pre-treated circuit board after the graphite adsorption treatment is soaked in a sulfuric acid solution under vacuum conditions.
In one embodiment, the pre-treated circuit board after the graphite adsorption treatment is soaked with a sulfuric acid solution under a pressure of 0.2atm to 0.7 atm.
In one embodiment, the pre-treated circuit board after the graphite adsorption treatment is subjected to a fixing treatment by using a sulfuric acid solution with a volume fraction of 0.5% -2%.
In one embodiment, the pre-treated circuit board after the graphite adsorption treatment is subjected to a fixing treatment for 10s to 20s by using a sulfuric acid solution with a volume fraction of 0.8% to 2%.
In one embodiment, the microetching and electroplating operation performed on the dried circuit board semi-finished product specifically includes the following steps:
carrying out microetching treatment on the circuit board semi-finished product;
and electroplating the circuit board semi-finished product subjected to the micro-etching treatment.
Compared with the prior art, the invention has at least the following advantages:
according to the hole metal process of the blind hole with the high aspect ratio of the circuit board, the hole metallization treatment is carried out on the circuit board to be treated by the obtained nano graphite hole metallization solution, so that the conductivity of the nano graphite layer is better ensured under the condition that the thickness of the nano graphite layer is smaller, the fixation treatment is carried out on the circuit board to be treated after the hole metallization treatment, namely, the fixation treatment is carried out on the circuit board to be treated before the nano graphite layer is dried and solidified, so that nano graphite particles which are not adsorbed with positive ions in the blind hole of the circuit board to be treated are removed, the thickness of the nano graphite layer of the blind hole in the circuit board to be treated is better reduced, the thickness uniformity of the nano graphite layer of the blind hole in the circuit board to be treated is better ensured, the expansion change degree of the nano graphite layer is better reduced, the problem that a copper plating layer in the blind hole is easy to peel off when the circuit board is cooled by high-temperature soldering tin, the poor conduction of the circuit board is further better ensured, the conduction stability of the circuit board to be treated is improved, the semi-graphite layer after the expansion change degree of the nano graphite layer is greatly, and the nano graphite layer is effectively improved in the adhesion stability of the nano graphite layer.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a flow chart of a via metal process for a high aspect ratio blind via of a wiring board according to one embodiment of the present invention;
fig. 2 is a partial view of an ultra high aspect ratio blind hole plate with its holes metallized as obtained in example 1;
fig. 3 is a partial view of an ultra high aspect ratio blind hole plate with its holes metallized as obtained in example 2;
fig. 4 is a partial view of an ultra high aspect ratio blind hole plate with its holes metallized as obtained in example 3.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully hereinafter with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a single embodiment.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
The application provides a hole metal process of a circuit board high aspect ratio blind hole. The hole metal process of the high aspect ratio blind hole of the circuit board comprises the following steps: obtaining a nano graphite hole metallization solution and a circuit board to be processed; cleaning and hole-trimming operation is carried out on the circuit board to be processed to obtain a pre-processed circuit board; carrying out graphite adsorption operation on the pretreated circuit board by adopting a nano graphite hole metallization solution so as to form a nano graphite layer on the hole wall and the hole bottom of the blind hole of the pretreated circuit board; performing fixation treatment on the pre-treated circuit board subjected to graphite adsorption treatment to remove part of nano graphite on the surface of the nano graphite layer in the blind hole of the pre-treated circuit board to obtain a circuit board semi-finished product; drying the semi-finished circuit board; and carrying out micro-etching electroplating operation on the dried circuit board semi-finished product to obtain the direct electroplating circuit board.
According to the hole metal process for the circuit board high-aspect-ratio blind hole, the nano graphite hole metallization solution is obtained to carry out hole metallization on the circuit board to be processed, so that the conductivity of a nano graphite layer is well ensured under the condition that the thickness of the nano graphite layer is small, the circuit board to be processed is subjected to fixation treatment after the hole metallization treatment, namely, the fixation treatment is carried out on the circuit board to be processed before the nano graphite layer is dried and solidified, so that nano graphite particles which are not adsorbed with positive ions in the blind hole of the circuit board to be processed are removed, the thickness of the nano graphite layer in the blind hole of the circuit board to be processed is well reduced, the thickness uniformity of the nano graphite layer in the blind hole of the circuit board to be processed is well ensured, the expansion change degree of the nano graphite layer is well reduced, the problem of poor conduction of the circuit board caused by the fact that a copper plating layer in the blind hole is easy to peel off when the circuit board is subjected to high-temperature soldering tin cooling due to the large expansion change degree of the nano graphite layer is solved, the conduction stability of the circuit board to be processed is well ensured, the circuit board to be processed is dried, the nano graphite layer is easily peeled off, the nano graphite layer adhesion stability of the circuit board is effectively improved, and the nano graphite layer adhesion stability of the nano graphite layer is effectively improved.
It should be noted that, since the nano-graphite hole metallization solution is used in the present application, the particle size of the nano-graphite contained in the nano-graphite hole metallization solution is 300nm to 700nm, which is lower than the cost of graphene, and the nano-graphite has better conductivity, so that the nano-graphite layer can have better conductivity under the condition of less usage amount, therefore, the fixation treatment is performed on the pre-treated circuit board after the graphite adsorption treatment, so that the nano-graphite particles which are not adsorbed by the positive ions in the blind holes of the pre-treated circuit board are removed, the thickness of the nano-graphite layer of the blind holes in the pre-treated circuit board is better reduced, the conductivity of the nano-graphite layer can be ensured under the condition that the thickness of the nano-graphite layer of the blind holes in the pre-treated circuit board is greatly reduced, the viscosity of the remaining nano-graphite particles is enhanced, the adsorption compactness is improved, the problem that the nano-graphite layer in the blind holes is loosened when expanding and the copper layer on the blind holes is forced to fall off is better reduced, and the conduction stability of the copper layer on the plated copper layer in the blind holes is better ensured.
It should be further noted that the nano graphite layer at the blind hole of the circuit board semi-finished product after the drying treatment is already cured, that is, the nano graphene is cured regardless of whether the part combined with the positive charge particles is cured, and then the sulfuric acid solution is used to remove the loose nano graphite on the surface of the nano graphite layer after the curing is performed, so that part of the nano graphite not combined with the positive charge particles is difficult to be washed away by the sulfuric acid solution, and only the loose nano graphite on the surface can be removed, thus the thickness of the nano graphite layer is difficult to be effectively reduced, and the thickness uniformity of the finally formed nano graphite is difficult to be ensured, the expansion degrees of the nano graphite layer at the blind hole of the circuit board semi-finished product are different, and the expansion change degree of the nano graphite layer at the blind hole of the circuit board semi-finished product is large, thereby the problem of poor copper plating layer in the blind hole due to the large expansion change degree of the nano graphite layer is difficult to be improved when the circuit board is subjected to high-temperature soldering tin cooling, and further the conduction problem among the circuit boards is caused.
In order to better understand the hole metal process of the high aspect ratio blind hole of the circuit board of the present application, the following further explains the hole metal process of the high aspect ratio blind hole of the circuit board of the present application:
referring to fig. 1, a via metallization process for a high aspect ratio blind via of a circuit board according to an embodiment includes the following steps:
s100, obtaining a nano graphite hole metallization solution and a circuit board to be processed. It can be understood that the particle size of the nano-graphite contained in the nano-graphite hole metallization solution is 300 nm-700 nm, the cost is lower compared with that of graphene, the nano-graphite has better conductivity, the nano-graphite layer can have better conductivity under the condition of less usage amount, and therefore, in order to enable the conductive layer formed in the blind hole to have better conductivity, in the application, the nano-graphite hole metallization solution is obtained to perform hole metallization processing on a circuit board to be processed, and the conductivity of the nano-graphite layer is better ensured under the condition of smaller thickness of the nano-graphite layer.
S200, cleaning and hole-trimming the circuit board to be processed to obtain the pre-processed circuit board. It can be understood that the cleaning and hole-finishing operation of the circuit board to be processed is the same as the cleaning and hole-finishing operation in the general direct electroplating process, and is used for removing oxide skin, grease, fingerprints and dirt on the copper surface of the circuit board, and adjusting the blind hole, so that the smoothness of the inner wall of the blind hole of the circuit board to be processed is well ensured, and the uniformity and the smoothness of a nano graphite hole layer formed on the inner wall of the blind hole of the circuit board to be processed are favorably realized.
S300, carrying out graphite adsorption operation on the pretreated circuit board by using a nano graphite hole metallization solution so as to form a nano graphite layer on the hole wall and the hole bottom of the blind hole of the pretreated circuit board. It can be understood that, because the main conductive substance used in the nano-graphite pore metallization solution is nano-graphite, the conductivity of the nano-graphite layer can be better ensured when the thickness of the nano-graphite layer formed after the nano-graphite pore metallization solution carries out graphite adsorption operation on the pretreated circuit board is smaller.
S400, performing fixation treatment on the pre-treated circuit board after the graphite adsorption treatment to remove partial nano graphite on the surface of the nano graphite layer in the blind hole of the pre-treated circuit board, and obtaining a semi-finished product of the circuit board. It can be understood that the fixing treatment is directly performed on the pre-treatment circuit board after the graphite adsorption treatment, that is, redundant nano graphite in the blind hole of the pre-treatment circuit board after the graphite adsorption treatment is directly removed, so that part of nano graphite on the side surface of the nano graphite layer far away from the hole wall and the hole bottom of the blind hole is removed, that is, nano graphite particles which are not adsorbed by positive ions in the blind hole of the pre-treatment circuit board are removed, the thickness of the nano graphite layer of the blind hole in the pre-treatment circuit board is better reduced under the condition of ensuring the conductivity of the nano graphite layer, the thickness uniformity of the nano graphite layer of the blind hole in the pre-treatment circuit board is better ensured, the expansion change degree of the nano graphite layer is better reduced, the problem that a copper plating layer in the blind hole is easy to peel off when the circuit board is subjected to high-temperature soldering tin cooling due to the large expansion change degree of the nano graphite layer, and the conduction failure among the circuit boards is further solved, and the conduction stability of the circuit board is better ensured.
And S500, drying the semi-finished product of the circuit board. It can be understood that the semi-finished product of the circuit board after the fixation treatment is dried, so that the solidification of the nano graphite layer is effectively realized, the adhesion stability of the nano graphite layer is improved, the stacking compactness of the nano graphite layer is improved, and the conductivity of the nano graphite layer is improved.
S600, carrying out micro-etching electroplating operation on the dried circuit board semi-finished product to obtain a direct electroplating circuit board, and better realizing the hole metallization of the circuit board.
According to the hole metal process for the circuit board with the high aspect ratio blind hole, the hole metallization treatment is carried out on the circuit board to be treated by the obtained nano graphite hole metallization solution, the conductivity of a nano graphite layer is well ensured under the condition that the thickness of the nano graphite layer is small, the fixation treatment is carried out on the circuit board to be treated after the hole metallization treatment, the fixation treatment is carried out on the circuit board to be treated before the nano graphite layer is dried and solidified, nano graphite particles which are not adsorbed with positive ions in the blind hole of the circuit board to be treated are removed, the thickness of the nano graphite layer of the blind hole in the circuit board to be treated is well reduced, the thickness uniformity of the nano graphite layer of the blind hole in the circuit board to be treated is well ensured, the expansion change degree of the nano graphite layer is well reduced, the problem of poor conduction of the circuit board caused by the fact that a copper plating layer in the blind hole is prone to be stripped when the circuit board is subjected to high-temperature soldering tin cooling due to the large expansion change degree of the nano graphite layer is solved, the conduction stability of the circuit board to be better ensured, the circuit board to be treated is dried and the semi-cured, and the nano graphite layer adhesion stability of the nano graphite layer is effectively improved.
In one embodiment, the nano-graphite pore metallization solution comprises nano-graphite, a binder, a dispersant, a surface energy promoter, and a basic buffer salt.
In one embodiment, the nano-graphite pore metallization solution comprises nano-graphite, a binder, a dispersant, a surface energy adjuvant, an alkaline buffer, and an antimicrobial agent.
In one embodiment, the nanographite pore metallization solution is similar to the conductive graphite pore metallization solution described in patent CN 112867285A, except that the conductive graphite in the conductive graphite pore metallization solution described in patent CN 112867285A is replaced by nanographite.
In one embodiment, the cleaning and hole-aligning operation is performed on the circuit board to be processed, and specifically comprises the following steps: the blind holes of the circuit board to be processed are cleaned by adopting the mixed solution of the polyethylene glycol and the hydroxyethyl ethylenediamine and adjusted to have positive charges on the hole walls, so that the circuit board to be processed is soaked and cleaned by the mixed solution of the polyethylene glycol and the hydroxyethyl ethylenediamine, the blind holes of the circuit board to be processed are better cleaned, the positive charges on the inner walls of the blind holes are better adsorbed, and the adsorbability of the blind holes of the circuit board to be processed on the nano graphite is further ensured.
In one embodiment, the graphite adsorption operation is performed on the pretreated circuit board by using a nano-graphite hole metallization solution under the ultrasonic vibration condition. It can be understood that if the hole metallization of the circuit board is carried out by adopting the chemical copper deposition process, the chemical copper deposition cannot be carried out under the ultrasonic vibration condition due to the property of chemical copper deposition liquid medicine, so that the efficiency of the chemical copper deposition is lower, and the uniformity of the formed plating layer is poorer.
In one embodiment, under the condition that the temperature is 20-24 ℃, the graphite adsorption operation is carried out on the pretreated circuit board for 40-60 s by using the nano graphite hole metallization solution, so that the nano graphite in the nano graphite hole metallization solution is well ensured to be fully adsorbed on the inner walls of the blind holes of the pretreated circuit board.
In one embodiment, under the vacuum condition, the graphite adsorption operation is performed on the pretreated circuit board by using the nano-graphite hole metallization solution, so that the pretreated circuit board is well fully infiltrated by the nano-graphite hole metallization solution.
In one embodiment, under the condition that the air pressure is 0.2 atm-0.7 atm, the graphite adsorption operation is carried out on the pretreated circuit board by adopting the nano-graphite hole metallization solution, so that the sufficient infiltration of the nano-graphite hole metallization solution on the pretreated circuit board is further ensured. In one embodiment, the fixing treatment of the pre-treated circuit board after the graphite adsorption treatment is specifically to soak the pre-treated circuit board after the graphite adsorption treatment by using a sulfuric acid solution. It can be understood that the sulfuric acid has a better acid etching performance, the sulfuric acid with a proper concentration is used for carrying out fixation treatment on the pre-treated circuit board, that is, the sulfuric acid with a proper concentration is used for carrying out soaking treatment on the nano graphite deposited on the pre-treated circuit board, so that the thickness of the nano graphite layer in the blind hole is more stable and can be removed more, and under the condition of removing more nano graphite, the uniformity of the nano graphite layer can be better ensured, namely, the nano graphite in the partial nano graphite layer can not be removed more or the nano graphite in the partial nano graphite layer can be completely removed, the thickness of the nano graphite layer after fixation treatment is better ensured to be smaller, the thickness uniformity is better, the problem that the copper layer on the electroplating is forced to fall off due to loosening when the nano graphite layer in the blind hole expands is better reduced, and the conduction stability of the copper layer on the electroplating in the blind hole is better ensured.
In one embodiment, the pre-treated circuit board after the graphite adsorption treatment is soaked in a sulfuric acid solution under vacuum. It can be understood that under the vacuum condition, the air in the blind hole of the pretreatment circuit board can be better discharged, and then make in the process of soaking the pretreatment circuit board after graphite adsorption treatment using sulfuric acid solution, sulfuric acid solution soaks the blind hole of the pretreatment circuit board fast and soaks the sufficiency better, the abundant contact of sulfuric acid solution and the nanometer graphite layer in the blind hole of the pretreatment circuit board has been better ensured, and then the thickness of the nanometer graphite layer after photographic fixing treatment has been better ensured to be less, and thickness uniformity is better, the problem that the copper layer on electroplating comes off is forced to come off by the pine when the nanometer graphite layer in the blind hole expands is better lightened, and then the conduction stability of the copper layer on electroplating in the blind hole has been better ensured.
In one embodiment, the pre-processing circuit board after the graphite adsorption processing is soaked by using the sulfuric acid solution under the condition that the air pressure is 0.2 atm-0.7 atm, so that the sulfuric acid solution is well contacted and soaked with the nano graphite layer in the blind holes of the pre-processing circuit board.
In one embodiment, the pre-treated circuit board after the graphite adsorption treatment is subjected to a fixing treatment by using a sulfuric acid solution with a volume fraction of 0.5% -2%. It can be understood that the concentration of sulfuric acid in the sulfuric acid solution has a great influence on the acid etching effect of the nano graphite layer in the blind hole of the pretreated circuit board, if the concentration of sulfuric acid in the sulfuric acid solution is high, transition acid etching of the nano graphite layer in the blind hole of the pretreated circuit board can be caused, even a copper layer in the blind hole of the pretreated circuit board is caused to be acid etched, so that the thickness of the nano graphite layer in the blind hole of the pretreated circuit board is too small, even the nano graphite layer in the blind hole of the pretreated circuit board is partially completely acid etched, the direct copper plating process of the circuit board is influenced, even the size of the blind hole of the circuit board is changed, and further the performance of the circuit board is influenced; if the concentration of sulfuric acid in the sulfuric acid solution is low, and the sulfuric acid solution has a poor effect of removing the nano graphite layer in the blind hole of the pretreated circuit board, that is, the problem that the nano graphite layer in the blind hole looses when expanding to force the copper layer on the electroplating to fall off is difficult to solve, and the effect of improving the viscosity and the adsorption compactness of the nano graphite particles cannot be achieved.
In one embodiment, a sulfuric acid solution with the volume fraction of 0.8-2% is adopted to perform fixation treatment on the pretreatment circuit board after the graphite adsorption treatment for 10-20 s, so that the thickness of the nano graphite layer after the fixation treatment is better ensured to be smaller, and the thickness uniformity is better.
In one embodiment, the microetching and electroplating operation of the semi-finished circuit board subjected to drying treatment specifically comprises the following steps:
carrying out microetching treatment on the circuit board semi-finished product;
and electroplating the microetched semi-finished product of the circuit board.
In one embodiment, the microetching treatment of the circuit board semi-finished product specifically comprises: and carrying out microetching treatment on the copper surface of the circuit board semi-finished product and the copper surface at the bottom of the blind hole by adopting a sodium persulfate-sulfuric acid system so as to microetch the copper surface of the circuit board semi-finished product and remove the nano graphite remained on the copper surface of the circuit board semi-finished product.
In one embodiment, the sodium persulfate-sulfuric acid system is a sodium persulfate-sulfuric acid system that is conventionally used in a direct plating process for microetching a copper surface of a circuit board semi-finished product.
In one embodiment, after the step of performing the microetching and electroplating operation on the dried semi-finished circuit board and before the step of obtaining the directly electroplated circuit board, the method comprises the following steps repeatedly and sequentially performed at least once:
cleaning and hole-trimming the circuit board semi-finished product;
carrying out graphite adsorption operation on the circuit board semi-finished product by adopting a nano graphite hole metallization solution so as to form a nano graphite layer on the hole wall and the hole bottom of the blind hole of the circuit board semi-finished product;
performing fixation treatment on the circuit board semi-finished product subjected to graphite adsorption treatment to remove partial nano graphite on the surface of the nano graphite layer in the blind hole of the circuit board semi-finished product;
drying the semi-finished circuit board;
and carrying out micro-etching electroplating operation on the dried circuit board semi-finished product.
The steps are repeated in sequence, so that the thickness and uniformity of the formed nano graphite layer are better ensured, the compactness of the formed nano graphite layer is better ensured, the problem that the copper layer on the electroplating is forced to fall off due to loosening when the nano graphite layer in the blind hole expands is better solved, and the conduction stability of the copper layer on the electroplating in the blind hole is better ensured.
Compared with the prior art, the invention has at least the following advantages:
according to the hole metal process for the circuit board high aspect ratio blind hole, the hole metallization treatment is carried out on the circuit board to be treated by the nano graphite hole metallization solution, the conductivity of a nano graphite layer is well ensured under the condition that the thickness of the nano graphite layer is small, the fixing treatment is carried out on the circuit board to be treated after the hole metallization treatment, namely the fixing treatment is carried out on the circuit board to be treated before the nano graphite layer is dried and solidified, so that nano graphite particles which are not adsorbed with positive ions in the blind hole in the circuit board to be treated are removed, the thickness of the nano graphite layer of the blind hole in the circuit board to be treated is well reduced, the thickness uniformity of the nano graphite layer of the blind hole in the circuit board to be treated is well ensured, then, the drying treatment is carried out on a semi-finished circuit board after the fixing treatment, the solidification of the nano graphite layer is effectively realized, the adhesion stability of the nano graphite layer is improved, the stacking compactness of the nano graphite layer is improved, the conductivity of the nano graphite layer is improved, finally, the residual nano graphite on all copper surfaces are completely removed through micro etching, the residual copper surfaces on the circuit board at the bottom, the bottom of the circuit board, and the problem of poor conduction of the circuit board due to soldering tin is further avoided, and the problem that the residual copper layers in the circuit board is well caused by high temperature soldering is solved.
Some specific examples are listed below, and if mentioned%, all are expressed in weight percent. It should be noted that the following examples are not intended to be exhaustive of all possible cases, and that the materials used in the following examples are commercially available without specific recitation.
Example 1
Machining a printed circuit board substrate FR-4 to form an ultra-high aspect ratio blind hole plate (the hole diameter is about 0.2mm, the hole depth is about 0.5 mm), removing glue residues by adopting an alkaline potassium permanganate method, cleaning blind holes of a circuit board to be processed by adopting M8601 (the main components are polyethylene glycol and hydroxyethyl ethylene diamine) and adjusting until the hole walls are positively charged, soaking the ultra-high aspect ratio blind hole plate in 60s, 28KHZ and 60s under the condition of 0.2atm, wherein the conductivity is less than 20us/cm and the overflow capacity is 5LPM, then soaking the ultra-high aspect ratio blind hole plate in a nanometer graphite hole metallization solution at the temperature of 20 ℃, soaking the ultra-high aspect ratio blind hole plate in 60s,3 sets of ultrasonic waves and 28KHZ under the condition of 0.2atm, then fishing out, putting the ultra-high aspect ratio blind hole plate into a sulfuric acid solution with the volume fraction of 0.5% and maintaining the atmospheric pressure for 20s under the condition of 0.2, then pure spraying and washing, the overflow capacity is 5LPM, then drying, and adopting SPS (50 g/L) -50% of H 2 SO 4 (2%) etching solution carries out micro-etching on the blind hole plate with the ultra-high aspect ratio, wherein the micro-etching rate is 0.21um, then the blind hole plate with the ultra-high aspect ratio is washed three times, 9s each time and 5LPM of overflow amount, dried and electroplated, and the blind hole plate with the ultra-high aspect ratio and metalized holes is obtained, and has the advantages of good conduction effect, no hole breakage of the blind holes and 100% conduction qualification rate.
Example 2
Machining printed circuit board substrate FR-4 to form an ultra-high aspect ratio blind hole plate (the hole diameter is about 0.5mm, the hole depth is about 2.0 mm), removing glue residue by adopting an alkaline potassium permanganate method, and adopting M8601 (the main components are polyethylene glycol and hydroxyethyl ethylDiamine) cleaning blind holes of a circuit board to be processed, adjusting the blind holes to have positive charges on the hole walls, 3 groups of ultrasonic waves, 28KHZ and 60s, then washing with water, wherein the conductivity is less than 20us/cm, the overflow capacity is 5LPM, then soaking 50s of the blind holes with the ultra-high aspect ratio in a nano graphite hole metallization solution at the air pressure of 0.5atm by M8603 (the main component is nano graphite) at the temperature of 22 ℃,3 groups of ultrasonic waves and 28KHZ, then fishing out, putting into a sulfuric acid solution with the volume fraction of 1 percent, keeping soaking for 15s at the air pressure of 0.5atm, then pure spraying and washing with water, the overflow capacity is 5LPM, cleaning blind holes of a circuit board to be processed by using M8601 (polyethylene glycol and hydroxyethyl ethylene diamine as main components) until the hole walls are positively charged, cleaning 3 groups of ultrasonic waves, 28KHZ and 60s, washing with water until the conductivity is less than 20us/cm and the overflow capacity is 5LPM, soaking the blind holes with the ultra-high aspect ratio in 50s,3 groups of ultrasonic waves and 28KHZ at the air pressure of 0.5atm by using M8603 (nano graphite hole metallization solution with the main component of nano graphite) at the temperature of 22 ℃, taking out, soaking in 1 volume percent sulfuric acid solution at the air pressure of 0.5atm for 15s, washing with pure water, spraying with the overflow capacity of 5LPM, drying, and using SPS (70 g/L) -50% H 2 SO 4 (3%) etching solution carries out microetching on the ultra-high aspect ratio blind hole plate, wherein the microetching rate is 0.21um, then the ultra-high aspect ratio blind hole plate is washed three times with 9s each time and 5LPM of overflow amount, dried and electroplated, so that the hole-metalized ultra-high aspect ratio blind hole plate is obtained, the conduction effect is good, the blind hole is not perforated, and the conduction qualified rate is 100%.
Example 3
Machining a printed circuit board substrate FR-4 to form an ultra-high aspect ratio blind hole plate (the hole diameter is 0.1mm, the hole depth is 0.16 mm), removing glue residues by adopting an alkaline potassium permanganate method, cleaning the blind holes of a circuit board to be processed by adopting M8601 (the main components are polyethylene glycol and hydroxyethyl ethylenediamine) and adjusting the blind holes until the hole walls are positively charged, carrying out 3 groups of ultrasonic waves, 28KHZ and 60s, then washing with water, wherein the conductivity is less than 20us/cm, the overflow capacity is 5LPM, then soaking the ultra-high aspect ratio blind hole plate by using M8603 (nano graphite hole metallized solution, the main component is nano graphite) at the temperature of 24 ℃ for 40s,3 groups of ultrasonic waves and 28KHZ, then fishing out, and throwing in the ultra-high aspect ratio blind hole plate under the condition that the air pressure is 0.7atmSoaking in 2% sulfuric acid solution at 0.7atm for 10s, pure spraying water, overflowing 5LPM, cleaning blind holes of circuit board with M8601 (polyethylene glycol and hydroxyethyl ethylenediamine as main components) until the walls of the blind holes are positively charged, soaking in 40s,3 ultrasonic waves, 28KHZ, and 3 ultrasonic waves at 0.7atm for 10s, taking out, soaking in 2% sulfuric acid solution at 0.7atm for 10s, pure spraying water, overflowing 5LPM, oven drying, and soaking in SPS (90 g/L) -50% H 2 SO 4 (4%) etching solution carries out micro-etching on the blind hole plate with the ultra-high aspect ratio, wherein the micro-etching rate is 0.21um, then the blind hole plate with the ultra-high aspect ratio is washed three times, 9s each time and 5LPM of overflow amount, dried and electroplated, and the blind hole plate with the ultra-high aspect ratio and metalized holes is obtained, and has the advantages of good conduction effect, no hole breakage of the blind holes and 100% conduction qualification rate.
Comparative example
Machining a printed circuit board substrate FR-4 to form an ultra-high aspect ratio blind hole plate (the hole diameter is about 0.5mm, the hole depth is about 2.0 mm), removing glue residues by adopting an alkaline potassium permanganate method, cleaning the blind holes of a circuit board to be processed by adopting M8601 (the main components are polyethylene glycol and hydroxyethyl ethylene diamine) and adjusting the blind holes until the hole walls are positively charged, 3 groups of ultrasonic waves, 28KHZ and 60s, then washing with water, the conductivity is less than 20us/cm, the overflow amount is 5LPM, then, under the condition that the temperature is 22 ℃, enabling M8603 (nano graphite hole metallization solution, the main component is nano graphite) to soak 50s,3 groups of ultrasonic waves and 28KHZ in the ultra-high aspect ratio blind hole plate under the condition that the air pressure is 0.5atm, then fishing out, pure spraying and washing with water for 3 times, drying, and using a sulfuric acid solution (50H) with the concentration of 20ml/L 2 SO 4 ) And (3) carrying out activation soaking, washing for three times, 9s each time, 5LPM of overflow amount, drying and electroplating to obtain the hole-metallized ultra-high aspect ratio blind hole plate, wherein the conduction effect is good, and the conduction qualified rate is 81.6%.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A hole metal process of a circuit board high aspect ratio blind hole is characterized by comprising the following steps:
obtaining a nano graphite hole metallization solution and a circuit board to be processed;
cleaning and hole-trimming the circuit board to be processed to obtain a pre-processed circuit board;
carrying out graphite adsorption operation on the pretreated circuit board by using the nano graphite hole metallization solution so as to form a nano graphite layer on the hole wall and the hole bottom of the blind hole of the pretreated circuit board;
performing fixation treatment on the pre-treated circuit board subjected to graphite adsorption treatment to remove partial nano graphite on the surface of the nano graphite layer in the blind hole of the pre-treated circuit board to obtain a circuit board semi-finished product;
drying the semi-finished circuit board;
and carrying out micro-etching electroplating operation on the dried circuit board semi-finished product to obtain the direct electroplating circuit board.
2. The process for forming a hole in a high aspect ratio blind hole of a circuit board according to claim 1, wherein the cleaning and hole-trimming operation is performed on the circuit board to be processed, and specifically comprises the following steps: and cleaning the blind holes of the circuit board to be processed by adopting a mixed solution of polyethylene glycol and hydroxyethyl ethylenediamine, and adjusting the blind holes until the hole walls are positively charged.
3. The hole metallization process of a circuit board high aspect ratio blind hole of claim 1, wherein said pre-treated circuit board is subjected to a graphite adsorption operation with said nano-graphite hole metallization solution under ultrasonic vibration conditions.
4. The hole metallization process for circuit boards with high aspect ratio blind holes of claim 1, wherein the nano-graphite hole metallization solution comprises nano-graphite, a binder, a dispersant, a surface energizer and an alkaline buffer salt.
5. The hole metal process of the circuit board with the high aspect ratio blind hole as claimed in claim 1, wherein the fixing treatment of the pre-treated circuit board after the graphite adsorption treatment is specifically soaking the pre-treated circuit board after the graphite adsorption treatment by using a sulfuric acid solution.
6. The process for forming a hole in a circuit board with a high aspect ratio blind hole according to claim 5, wherein the pre-treated circuit board after the graphite adsorption treatment is soaked in a sulfuric acid solution under vacuum.
7. The hole metal process of the circuit board high aspect ratio blind hole of claim 5, wherein the pre-treated circuit board after graphite adsorption treatment is soaked with sulfuric acid solution under the air pressure of 0.2atm to 0.7 atm.
8. The process for forming a hole in a circuit board with a high aspect ratio blind hole according to claim 1, wherein a sulfuric acid solution with a volume fraction of 0.5-2% is used for fixing the pre-treated circuit board after graphite adsorption treatment.
9. The process for forming a hole in a circuit board with a high aspect ratio blind hole according to claim 1, wherein a sulfuric acid solution with a volume fraction of 0.8-2% is used for carrying out a fixation treatment on the pre-treated circuit board after the graphite adsorption treatment for 10-20 s.
10. The hole metal process of the circuit board high aspect ratio blind hole as claimed in claim 1, wherein the microetching and electroplating operation of the dried circuit board semi-finished product specifically comprises the following steps:
carrying out microetching treatment on the circuit board semi-finished product;
and electroplating the circuit board semi-finished product subjected to the micro-etching treatment.
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| CN202211193367.0A CN115529746A (en) | 2022-09-28 | 2022-09-28 | Hole metal process for high-aspect-ratio blind hole of circuit board |
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| CN202211193367.0A CN115529746A (en) | 2022-09-28 | 2022-09-28 | Hole metal process for high-aspect-ratio blind hole of circuit board |
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| CN202211193367.0A Pending CN115529746A (en) | 2022-09-28 | 2022-09-28 | Hole metal process for high-aspect-ratio blind hole of circuit board |
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