CN113354449B - Method for preventing silver on copper side wall of ceramic copper-clad substrate during chemical silver deposition - Google Patents
Method for preventing silver on copper side wall of ceramic copper-clad substrate during chemical silver deposition Download PDFInfo
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- CN113354449B CN113354449B CN202110805886.7A CN202110805886A CN113354449B CN 113354449 B CN113354449 B CN 113354449B CN 202110805886 A CN202110805886 A CN 202110805886A CN 113354449 B CN113354449 B CN 113354449B
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
- C04B41/81—Coating or impregnation
- C04B41/89—Coating or impregnation for obtaining at least two superposed coatings having different compositions
- C04B41/90—Coating or impregnation for obtaining at least two superposed coatings having different compositions at least one coating being a metal
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
- C04B41/52—Multiple coating or impregnating multiple coating or impregnating with the same composition or with compositions only differing in the concentration of the constituents, is classified as single coating or impregnation
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- Manufacturing Of Printed Wiring (AREA)
Abstract
The invention relates to the technical field of semiconductors. The method comprises the following steps that firstly, an ink layer is silk-screened, the ink layer comprises a gap filling layer filled in the gap, and the ink layer also comprises an upper ink layer covered on the gap filling layer and the copper layer; step two, prebaking; baking the ink layer to realize that the ink layer is not stuck to the exposure negative film; thirdly, carrying out primary exposure by adopting an exposure negative film; a shading area is arranged on the exposure negative film, and the edge of the shading area shades the outer edge of the gap; developing a graph; step five, secondary exposure is carried out, and the printing ink is solidified; the energy intensity of the first exposure is lower than that of the second exposure. After the treatment, the invention prevents the copper side wall from being silvered during silvering, and simultaneously avoids the ink at the gap from overflowing to pollute the silver surface and the production line during silvering/film removing.
Description
Technical Field
The invention relates to the technical field of semiconductors, in particular to an exposure method for preventing silver on a copper side wall during chemical silver deposition.
Background
The existing DCB substrate and AMB substrate are a new surface treatment process for improving the high-temperature resistance of a power device, and the silver sintering process is used for replacing the traditional soldering process by a customer, and the parts are combined with the DCB substrate and the AMB substrate through silver.
Because the melting temperature of silver is far higher than that of the lead-free soldering tin bar SnAg3.5, the DCB substrate and AMB substrate surface selective silver technology has great advantages in the power electronic packaging in the high-temperature application field and the high-reliability field. Although existing manufacturers at home and abroad adopt a technology for carrying out selective silver treatment on the surface of a substrate, the technology has one defect: this defect is more prevalent when the copper sidewalls have silver, especially when the silver plated areas are close to the copper edges. After the encapsulation, the adhesive has poor bonding force with the silver layer, so that the adhesive layer is easily separated from the silver layer, and the silver layer is exposed outside to easily cause metal migration, which leads to the performance reduction of the product after the customer encapsulation and influences the reliability of the power device.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a method for preventing the silver on the copper side wall of a ceramic copper-clad substrate during chemical silver deposition, so as to solve at least one technical problem.
In order to achieve the above object, the present invention provides a method for preventing silver from being deposited on a copper side wall of a ceramic copper-clad substrate during chemical silver deposition, wherein the ceramic copper-clad substrate comprises a copper layer and a ceramic layer which are arranged up and down, and a gap is formed on the copper layer, the method comprising the steps of:
step one, screen printing an ink layer, wherein the ink layer comprises a gap filling layer filled in a gap and an upper ink layer covering the gap filling layer and the copper layer;
step two, prebaking;
baking the ink layer to realize that the ink layer is not stuck to the exposure negative film;
thirdly, carrying out primary exposure by adopting an exposure negative film;
a shading area is arranged on the exposure negative film, and the edge of the shading area shades the outer edge of the gap;
step five, after the graph is developed, secondary exposure is carried out, and the printing ink is solidified;
the energy intensity of the first exposure is lower than the energy intensity of the second exposure.
Preferably, in the step one, the ink is applied to the mesh cloth of the frame, and the printing knife with a squeegee mounted on the screen printer extrudes the ink to the surface and gaps of the product through the mesh holes of the mesh cloth at a certain printing speed, thereby forming the screen printing ink layer.
Further preferably, in the first step, a screen with the mesh number of 100 is used for screen printing.
Further preferably, an orthographic projection of an edge of the light-shielding region is located within a coverage area of the orthographic projection of the gap, and the edge of the light-shielding region extends 0.1-0.2mm beyond the edge of the gap.
Further preferably, in the second step, the pre-baking temperature is 70-75 ℃ and the time is 35-45 min.
Is convenient for realizing prebaking.
Further preferably, in the second step, the wavelength of the exposure treatment is 360nm to 410nm.
Further preferably, in step three, the exposure energy is 500mJ/cm 2 ～600mJ/cm 2 。
More preferably, in the third step, the exposure time is 1min to 2min.
Further preferably, in the fifth step, the wavelength of the exposure treatment is 360nm to 410nm.
Further preferably, in step five, the exposure energy is 4000mJ/cm 2 ～4500mJ/cm 2 。
More preferably, in the fourth step, the developing time is 1min to 2min.
Further preferably, in the fifth step, the exposure time is 5min to 8min.
Has the advantages that: 1. this patent method is applicable to the tight copper lateral wall edge in silver-plated region edge (also be the clearance edge) when distance, and the silver edge is zero apart from copper edge distance promptly, through the configuration optimization of exposure film, solves the counterpoint among the exposure process and slightly squints the phenomenon that has the silver face to expose copper and silver on the lateral wall, guarantees the tight copper edge in silver-plated region edge, and lateral wall copper does not go up silver, and the method is simple and convenient, easily volume production.
The shading area (black area) of the exposure negative extends out about 0.1-0.2mm slightly more than the gap edge, even if slight deviation exists during exposure, because the black area of the negative is large enough and the surface ink is tightly jointed with the exposure negative, the black area can be completely protected from polymerization caused by UV light irradiation, the ink at the gap is volatilized by the solvent after prebaking, the ink shrinks and sinks downwards, the black area can not be tightly jointed with the negative, the black area can be irradiated by light, and the ink at the gap can still be polymerized.
2. After prebaking, two energy exposures: the method comprises the steps of firstly carrying out low-energy exposure, developing a pattern, then carrying out high-energy full-plate exposure, solidifying the ink at the gap, preventing the silver from being coated on the copper side wall when the silver is dissolved, and simultaneously avoiding the ink at the gap from overflowing to pollute a silver surface and a production line when the silver is dissolved/the film is removed.
Drawings
FIG. 1 is a flowchart of the embodiment 1;
FIG. 2 is a schematic diagram of steps two through four of the present invention;
FIG. 3 is a schematic view of the structure of the silver-coated product of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
Specific example 1: the ceramic copper-clad substrate comprises a copper layer and a ceramic layer which are arranged up and down, and a gap is formed in the copper layer.
Referring to fig. 1 and 2, a method for preventing silver on a copper side wall of a ceramic copper-clad substrate during chemical silver deposition comprises the following steps:
step one, screen printing an ink layer, wherein the ink layer comprises a gap filling layer filled in a gap and an upper ink layer covering the gap filling layer and the copper layer;
in the first step, a screen printing plate with the mesh number of 100 is adopted for screen printing.
Step two, prebaking; the pre-baking temperature is 70-75 ℃, and the time is 35-45 min;
and (4) drying the ink layer to realize that the ink layer is not stuck to the exposure negative film.
Thirdly, carrying out primary exposure by adopting an exposure negative film;
a shading area is arranged on the exposure negative film, and the edge of the shading area shades the outer edge of the gap; the orthographic projection of the edge of the light shielding area is positioned in the coverage area of the orthographic projection of the gap, and the edge of the light shielding area extends out 0.1-0.2mm beyond the edge of the gap. That is, the edge of the shading area encloses a closed structure, and the inside of the closed structure is a light-transmitting area. The closed structure is positioned in the coverage area of the orthographic projection of the gap, and the distance between the closed structure and the gap is 0.1-0.2mm.
The wavelength of the exposure treatment is 360 nm-410 nm. The light energy is 500mJ/cm 2 ～600mJ/cm 2 。
In the third step, the exposure time is 1 min-2 min.
And step four, developing the graph. The developing time is 1-2 min.
Step five, secondary exposure is carried out, and the printing ink is solidified;
exposure to lightThe wavelength of the treatment is 360 nm-410 nm. The exposure energy was 4000mJ/cm 2 ～4500mJ/cm 2 . In the third step, the exposure time is 1 min-2 min.
By the method, the situation that the copper on the side wall is not silvered during chemical silver deposition can be ensured.
Has the advantages that: 1. the method is suitable for the distance between the edge of the tight copper side wall (namely the gap edge) of the silver plating area, namely the distance between the silver edge and the copper edge is zero, through the structural optimization of the exposure film, the phenomena that the copper is exposed on the silver surface and the silver is added on the side wall when the alignment is slightly deviated in the exposure process are solved, the tight copper edge of the silver plating area is ensured, the copper on the side wall is not added, the method is simple and convenient, and the mass production is easy.
The shading area (black area) of the exposure negative extends out about 0.1-0.2mm slightly more than the gap edge, even if slight deviation exists during exposure, because the black area of the negative is large enough and the surface ink is tightly jointed with the exposure negative, the black area can be completely protected from polymerization caused by UV light irradiation, the ink at the gap is volatilized by the solvent after prebaking, the ink shrinks and sinks downwards, the black area can not be tightly jointed with the negative, the black area can be irradiated by light, and the ink at the gap can still be polymerized.
3. After prebaking, two energy exposures: the low-energy exposure is carried out firstly, after a pattern is developed, the high-energy full-plate exposure is carried out, the printing ink at the gap is solidified, the silver on the copper side wall is prevented when silver is dissolved, and meanwhile, the phenomenon that the printing ink at the gap overflows to pollute a silver surface and a production line when the silver is dissolved/a film is removed is avoided.
The ceramic copper-clad substrate treated by the method is subjected to chemical silver deposition, and the side wall copper is not silver-coated. Referring to the cross-sectional structure shown in fig. 3, specifically, the surface silver-plated region has no poor copper exposure, the surface silver-plated region is clearly separated from the sidewall copper, and the copper surface of the spaced sidewall has no poor silver exposure.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that it is obvious to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present invention, and these modifications and improvements should also be considered as the protection scope of the present invention.
Claims (3)
1. The method for preventing the silver on the copper side wall of the ceramic copper-clad substrate from being coated during chemical silver deposition is characterized by comprising the following steps of:
step one, screen printing an ink layer, wherein the ink layer comprises a gap filling layer filled in a gap and an upper ink layer covering the gap filling layer and the copper layer;
step two, prebaking;
baking the ink layer to realize that the ink layer is not adhered to the exposure negative film; the pre-baking temperature is 70-75 ℃, and the time is 35-45 min;
thirdly, carrying out primary exposure by adopting an exposure negative film;
a shading area is arranged on the exposure negative film, and the edge of the shading area shades the outer edge of the gap; the orthographic projection of the edge of the shading area is positioned in the coverage area of the orthographic projection of the gap, and the edge of the shading area extends out 0.1-0.2mm than the edge of the gap;
the wavelength of the exposure treatment is 360 nm-410 nm; the exposure energy was 500mJ/cm 2 ～600mJ/cm 2 (ii) a The exposure time is 1 min-2 min;
developing a graph;
step five, secondary exposure is carried out, and the printing ink is solidified;
the wavelength of the exposure treatment is 360 nm-410 nm; the exposure energy was 4000mJ/cm 2 ～4500mJ/cm 2 The exposure time is 5 min-8 min.
2. The method for chemical silver deposition of the ceramic copper-clad substrate according to claim 1, wherein the copper side wall is free from silver, and the method comprises the following steps: in the first step, ink is applied to the screen cloth of the screen frame, and a printing knife provided with a doctor blade on the screen printer extrudes the ink to the surface and gaps of a product through the mesh holes of the screen cloth at a certain printing speed, so that a screen printing ink layer is formed.
3. The method for chemical silver deposition of the ceramic copper-clad substrate according to claim 1, wherein the copper side wall is free from silver, and the method comprises the following steps: in the first step, a screen printing plate with the mesh number of 100 is adopted for screen printing.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110805886.7A CN113354449B (en) | 2021-07-16 | 2021-07-16 | Method for preventing silver on copper side wall of ceramic copper-clad substrate during chemical silver deposition |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110805886.7A CN113354449B (en) | 2021-07-16 | 2021-07-16 | Method for preventing silver on copper side wall of ceramic copper-clad substrate during chemical silver deposition |
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| CN113354449A CN113354449A (en) | 2021-09-07 |
| CN113354449B true CN113354449B (en) | 2022-10-11 |
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| US7473580B2 (en) * | 2006-05-18 | 2009-01-06 | International Business Machines Corporation | Temporary chip attach using injection molded solder |
| US20120061698A1 (en) * | 2010-09-10 | 2012-03-15 | Toscano Lenora M | Method for Treating Metal Surfaces |
| CN102361542B (en) * | 2011-09-30 | 2013-08-07 | 东莞市五株电子科技有限公司 | Manufacturing process of printed circuit board with steps |
| CN106373891B (en) * | 2016-08-31 | 2019-04-23 | 江西芯创光电有限公司 | Encapsulating carrier plate lateral protection method |
| CN108601234A (en) * | 2018-04-04 | 2018-09-28 | 东莞市武华新材料有限公司 | A kind of ceramic surface metal layer preparation method |
| CN108389805A (en) * | 2018-04-28 | 2018-08-10 | 长电科技（滁州）有限公司 | A kind of high reliability planar salient point type encapsulating method and structure |
| CN111050487A (en) * | 2019-12-23 | 2020-04-21 | 上海美维电子有限公司 | Solder mask layer manufacturing method, printed circuit board manufacturing method and printed circuit board |
| CN112469202A (en) * | 2020-11-24 | 2021-03-09 | 绍兴德汇半导体材料有限公司 | Selective silver plating method applied to copper-clad ceramic substrate |
| CN112492764B (en) * | 2021-01-27 | 2021-04-20 | 四川英创力电子科技股份有限公司 | Method for eliminating solder resist ink in through hole of printed circuit board |
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