CN111132466A - Method for preventing metal ion migration on surface of PCB - Google Patents
Method for preventing metal ion migration on surface of PCB Download PDFInfo
- Publication number
- CN111132466A CN111132466A CN201911381624.1A CN201911381624A CN111132466A CN 111132466 A CN111132466 A CN 111132466A CN 201911381624 A CN201911381624 A CN 201911381624A CN 111132466 A CN111132466 A CN 111132466A
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- pcb
- coating
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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
- H05K3/28—Applying non-metallic protective coatings
Abstract
The invention relates to the technical field of PCB substrate packaging, in particular to a method for preventing metal ion migration on the surface of a PCB, which comprises the following steps: the PCB to be coated is subjected to plasma cleaning, the PCB is placed on a lining board with the coating treatment surface facing upwards, the lining board is placed into coating vacuum equipment for vacuumizing treatment, then the PCB is subjected to coating treatment, and after the coating is finished, the PCB is taken out after being cooled to room temperature and is timely placed into a nitrogen cabinet for storage. The invention mainly aims at the problem that the PCB is subjected to special surface coating treatment before a chip is installed, and the formed protective layer structure can effectively prevent the ion migration phenomenon of the metal circuit between the metal circuits or the bonding pads on the PCB under the multiple double image effects of moisture, chemical erosion, voltage and the like.
Description
Technical Field
The invention relates to the technical field of PCB substrate packaging, in particular to a method for preventing metal ions on the surface of a PCB from migrating.
Background
In recent years, the packaging of chips such as ICs, MEMS, and LEDs is continuously developing towards smaller size, which makes the metal circuit of the PCB substrate used for packaging denser, layout more complex, and corresponding pitch narrower. The new trend of these PCB boards for packaging greatly increases the risk of metal ion migration of the packaged electronic product, thereby causing the failure of the whole packaged electronic product.
The conventional method for preventing metal migration of metal lines and pads on a PCB substrate is mainly to perform various chemical or electroplating treatments on the metal lines and pads of the PCB, such as electroless nickel immersion gold, electroplating nickel gold, electroless nickel-palladium gold, etc., and then fill the chip and the metal lines with a packaging adhesive to isolate the chip and the metal lines from the external environment. The principle is that the Cu or Ag which is most easy to generate chemical corrosion and metal migration is covered by inert metal (such as Au), so as to achieve the effect of protecting active metal.
The existing PCB substrate surface treatment and packaging adhesive technology can well protect chips and metal circuits when the circuit spacing is wider, but the spacing is smaller and smaller as the metal circuits are thinner and thinner, the existing PCB surface treatment methods are difficult to effectively protect active metal (such as Cu) on the lower layer, and the metal circuits and bonding pads are easy to have metal migration under some high-humidity and high-temperature environments. In addition, the environmental protection requirements are more and more strict, and the surface treatment modes of the PCB, such as electroplating and chemical plating, are more and more limited.
Disclosure of Invention
The invention provides a method for preventing metal ion migration on the surface of a PCB (printed Circuit Board), which mainly aims at the problem that a PCB is subjected to special surface coating treatment before a chip is installed, and a formed protective layer structure can effectively prevent the ion migration phenomenon of metal circuits between metal circuits or bonding pads on the PCB under the multi-ghost effects of moisture, chemical erosion, voltage and the like.
The technical scheme of the invention is as follows:
a method for preventing metal ion migration on the surface of a PCB comprises the following steps:
s1: carrying out plasma cleaning on the PCB to be subjected to film coating treatment;
s2: placing the cleaned PCB on a lining board, wherein the coating treatment surface faces upwards;
s3: putting the lining plate into a coating vacuum device for vacuum-pumping treatment, wherein the vacuum degree is controlled to be 10-3To 10-5Pa;
s4: performing film coating treatment on the PCB, wherein the film coating material is SiO2、TiO2、Al2O2、Si3N4And one or more of AlN, the coating process is one of electron beam evaporation, magnetron sputtering or atomic layer deposition, and the coating temperature is controlled between 50 and 120 ℃;
s5: and after the film coating is finished, taking out the PCB after the PCB is cooled to room temperature, and putting the PCB in a nitrogen cabinet for storage in time.
The invention carries out vacuum-pumping treatment before film coating, and the vacuum degree at least reaches 10-3Otherwise, water vapor or other impurity gases in the cavity of the coating equipment can negatively affect the subsequent coating process, so that the density of the film is reduced, even holes are generated, and the film becomes invalid. The higher the degree of vacuum, the better, but based on the limit of the vacuum pump, the degree of vacuum is controlled to 10 in the present invention-3To 10-5And the quality of the prepared film layer is good.
The film coating temperature of the invention also has a crucial influence on the quality and compactness of the film coating layer, the film coating temperature is not more than 120 ℃, otherwise, the PCB plate material is damaged or burned black, and the SiO is generated based on the difference of the film coating modes2、TiO2、Al2O2、Si3N4And the activity of coating materials such as AlN and the like, and the coating temperature of more than 50 ℃ can meet the film forming quality and compactness of various coating materials, so the coating temperature is controlled between 50 ℃ and 120 ℃, the deformation and the thermal damage of a PCB are avoided, and the film forming quality and the compactness are effectively ensured.
Further, the thickness of the coating film is controlled between 10 nm and 1000 nm. The coating films with different thicknesses can be prepared according to different customer requirements, and the common thickness is between 10 and 1000 nm.
Further, the degree of vacuum is preferably controlled to 10-4Pa。
Further, SiO is preferably used as the coating material2。
Further, magnetron sputtering is preferably adopted as the coating process.
Further, the plating temperature is preferably 100 degrees celsius.
The method ensures plasma cleaning before coating the PCB and improves the film adhesion of the coating surface of the PCB, thereby improving the reliability of the inert protective layer formed by the inert coating material; the vacuum degree before coating needs to reach a specified range, the coating temperature needs to be strictly controlled, and the proper vacuum degree and temperature can effectively ensure the film quality and compactness of the inert protective layer; the coating temperature cannot be too high, so that the PCB is not deformed and is not damaged by heat; and ensuring the nitrogen preservation of the PCB after the film coating is finished so as to ensure the compact effect and quality of the inert protective layer.
The invention has the beneficial effects that:
the invention can be used as the surface pretreatment of the PCB before the chip packaging, and on the basis of ensuring that the existing packaging process is not influenced, the invention can greatly improve the air tightness of the packaging and simultaneously fundamentally prevent the surface metal of the PCB from generating ion migration, thereby improving the reliability of the packaging device;
the invention also has certain environmental protection property, and can be used as a potential effective substitute for the surface treatment (including chemical plating and electroplating of inert metal) of the existing PCB in a PCB factory, thereby ensuring the use function of rear-section packaging in the manufacture of the PCB and simultaneously causing less environmental pollution.
Drawings
FIG. 1 is a schematic flow diagram of the present invention.
Detailed Description
The drawings are for illustrative purposes only and are not to be construed as limiting the patent; for the purpose of better illustrating the embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted. The positional relationships depicted in the drawings are for illustrative purposes only and are not to be construed as limiting the present patent.
Example 1:
as shown in fig. 1, the present invention mainly relates to a vacuum coating process, which ensures uniform preparation of a desired inert protective layer in a low-temperature and dust-free environment.
The preparation method comprises the following steps:
s1: carrying out plasma cleaning on the PCB to be subjected to film coating treatment;
s2: placing the cleaned PCB on a lining board, wherein the coating treatment surface faces upwards;
s3: putting the lining plate into a coating vacuum device for vacuum-pumping treatment, wherein the vacuum degree is controlled to be 10-3To 10-5Pa;
s4: performing film coating treatment on the PCB, wherein the film coating material is SiO2、TiO2、Al2O2、Si3N4And one or more of AlN, the coating process is one of electron beam evaporation, magnetron sputtering or atomic layer deposition, and the coating temperature is controlled between 50 and 120 ℃;
s5: and after the film coating is finished, taking out the PCB after the PCB is cooled to room temperature, and putting the PCB in a nitrogen cabinet for storage in time.
The invention carries out vacuum-pumping treatment before film coating, and the vacuum degree at least reaches 10-3Otherwise, water vapor or other impurity gases in the cavity of the coating equipment can negatively affect the subsequent coating process, so that the density of the film is reduced, even holes are generated, and the film becomes invalid. The higher the degree of vacuum, the better, but based on the limit of the vacuum pump, the degree of vacuum is controlled to 10 in the present invention-3To 10-5And the quality of the prepared film layer is good.
In this embodiment, the degree of vacuum is preferably controlled to 10-4Pa。
The film coating temperature of the invention also has a crucial influence on the quality and compactness of the film coating layer, the film coating temperature is not more than 120 ℃, otherwise, the PCB plate material is damaged or burned black, and the SiO is generated based on the difference of the film coating modes2、TiO2、Al2O2、Si3N4The activity of the coating materials such as AlN and the like, and the coating temperature of more than 50 ℃ can meet the film-forming quality and compactness of various coating materials, so the coating temperature is controlled to be 50-120 DEG CMeanwhile, the deformation and the thermal damage of the PCB are avoided, and the film forming quality and the compactness are effectively ensured.
In this embodiment, SiO is preferably used as the coating material2The coating temperature is preferably 100 ℃, and the coating process is preferably magnetron sputtering.
In this embodiment, the thickness of the plating film is controlled to be 10 to 1000 nm. The coating films with different thicknesses can be prepared according to different customer requirements, and the common thickness is between 10 and 1000 nm.
The method is to plate one or more layers of SiO on the surface of the PCB board by using a film coating process2、TiO2、Al2O2、Si3N4And the inert protective layer or layers of inert protective layers formed by AlN and other inert materials completely cut off the possibility of electrochemical reaction of the metal on the surface of the PCB.
The method ensures plasma cleaning before the coating of the PCB and improves the film adhesion of the coating surface of the PCB, thereby improving the reliability of the inert protective layer; the vacuum degree before coating needs to reach a specified range, the coating temperature needs to be strictly controlled, and the proper vacuum degree and temperature can effectively ensure the film quality and compactness of the inert protective layer; the coating temperature cannot be too high, so that the PCB is not deformed and is not damaged by heat; and ensuring the nitrogen preservation of the PCB after the film coating is finished so as to ensure the compact effect and quality of the inert protective layer.
The invention can well protect metal circuits and bonding pads with extremely small spacing and extremely fine size, and the film coating treatment can be carried out on the basis of the surface treatment of the existing PCB, and can also be directly carried out on the PCB without the surface treatment, thereby not influencing the existing PCB preparation process and chip packaging process. The method ensures that the required inert protective layer is uniformly prepared under the low-temperature and dust-free environment state.
The invention can be used as the surface pretreatment of the PCB before the chip packaging, and on the basis of ensuring that the existing packaging process is not influenced, the invention can greatly improve the air tightness of the packaging and simultaneously fundamentally prevent the surface metal of the PCB from generating ion migration, thereby improving the reliability of the packaging device;
the invention also has certain environmental protection property, and can be used as a potential effective substitute for the surface treatment (including chemical plating and electroplating of inert metal) of the existing PCB in a PCB factory, thereby ensuring the use function of rear-section packaging in the manufacture of the PCB and simultaneously causing less environmental pollution.
It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.
Claims (6)
1. A method for preventing metal ion migration on the surface of a PCB is characterized by comprising the following steps:
s1: carrying out plasma cleaning on the PCB to be subjected to film coating treatment;
s2: placing the cleaned PCB on a lining board, wherein the coating treatment surface faces upwards;
s3: putting the lining plate into a coating vacuum device for vacuum-pumping treatment, wherein the vacuum degree is controlled to be 10-3To 10-5Pa;
s4: performing film coating treatment on the PCB, wherein the film coating material is SiO2、TiO2、Al2O2、Si3N4And one or more of AlN, the coating process is one of electron beam evaporation, magnetron sputtering or atomic layer deposition, and the coating temperature is controlled between 50 and 120 ℃;
s5: and after the film coating is finished, taking out the PCB after the PCB is cooled to room temperature, and putting the PCB in a nitrogen cabinet for storage in time.
2. The method of claim 1, wherein the thickness of the plated film is controlled to be 10-1000 nm.
3. The method for preventing the metal ions on the surface of the PCB from migrating according to claim 1, wherein the vacuum degree is controlled to be 10-4Pa。
4. The method of claim 1, wherein the coating material is SiO2。
5. The method as claimed in claim 1, wherein the coating process is magnetron sputtering.
6. The method of claim 1, wherein the coating temperature is 100 ℃.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911381624.1A CN111132466A (en) | 2019-12-27 | 2019-12-27 | Method for preventing metal ion migration on surface of PCB |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911381624.1A CN111132466A (en) | 2019-12-27 | 2019-12-27 | Method for preventing metal ion migration on surface of PCB |
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| Publication Number | Publication Date |
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| CN111132466A true CN111132466A (en) | 2020-05-08 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201911381624.1A Pending CN111132466A (en) | 2019-12-27 | 2019-12-27 | Method for preventing metal ion migration on surface of PCB |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115493780A (en) * | 2022-11-16 | 2022-12-20 | 苏州晶台光电有限公司 | Method for detecting air tightness of LED product |
Citations (7)
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| US20020093109A1 (en) * | 2001-01-12 | 2002-07-18 | Kline Eric Vance | Composition and method for containing metal ions in electronic devices |
| CN102686034A (en) * | 2012-04-27 | 2012-09-19 | 杨白 | Film coating method for electronic circuit board |
| CN104123564A (en) * | 2014-07-23 | 2014-10-29 | 上海思立微电子科技有限公司 | Fingerprint identification device and assembly with coated film protective layer |
| CN104233228A (en) * | 2014-07-18 | 2014-12-24 | 许昌学院 | Full-automatic non-contact vacuum coating method and equipment |
| CN106480414A (en) * | 2016-09-15 | 2017-03-08 | 广东思泉新材料股份有限公司 | A kind of manufacture method of waterproof electronic product |
| CN109072430A (en) * | 2016-04-12 | 2018-12-21 | 皮考逊公司 | It is applied by ALD coated with for inhibiting metal whisker |
| CN208422947U (en) * | 2018-05-03 | 2019-01-22 | 深圳市丽晶光电科技股份有限公司 | A kind of LED encapsulation structure of plated film |
-
2019
- 2019-12-27 CN CN201911381624.1A patent/CN111132466A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020093109A1 (en) * | 2001-01-12 | 2002-07-18 | Kline Eric Vance | Composition and method for containing metal ions in electronic devices |
| CN102686034A (en) * | 2012-04-27 | 2012-09-19 | 杨白 | Film coating method for electronic circuit board |
| CN104233228A (en) * | 2014-07-18 | 2014-12-24 | 许昌学院 | Full-automatic non-contact vacuum coating method and equipment |
| CN104123564A (en) * | 2014-07-23 | 2014-10-29 | 上海思立微电子科技有限公司 | Fingerprint identification device and assembly with coated film protective layer |
| CN109072430A (en) * | 2016-04-12 | 2018-12-21 | 皮考逊公司 | It is applied by ALD coated with for inhibiting metal whisker |
| CN106480414A (en) * | 2016-09-15 | 2017-03-08 | 广东思泉新材料股份有限公司 | A kind of manufacture method of waterproof electronic product |
| CN208422947U (en) * | 2018-05-03 | 2019-01-22 | 深圳市丽晶光电科技股份有限公司 | A kind of LED encapsulation structure of plated film |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115493780A (en) * | 2022-11-16 | 2022-12-20 | 苏州晶台光电有限公司 | Method for detecting air tightness of LED product |
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Application publication date: 20200508 |