CN110944456A - Circuit board solder mask process - Google Patents
Circuit board solder mask process Download PDFInfo
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- CN110944456A CN110944456A CN201911296059.9A CN201911296059A CN110944456A CN 110944456 A CN110944456 A CN 110944456A CN 201911296059 A CN201911296059 A CN 201911296059A CN 110944456 A CN110944456 A CN 110944456A
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- screen printing
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- circuit board
- solder mask
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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
- H05K3/02—Apparatus or processes for manufacturing printed circuits in which the conductive material is applied to the surface of the insulating support and is thereafter removed from such areas of the surface which are not intended for current conducting or shielding
- H05K3/06—Apparatus or processes for manufacturing printed circuits in which the conductive material is applied to the surface of the insulating support and is thereafter removed from such areas of the surface which are not intended for current conducting or shielding the conductive material being removed chemically or electrolytically, e.g. by photo-etch process
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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
- H05K3/0094—Filling or covering plated through-holes or blind plated vias, e.g. for masking or for mechanical reinforcement
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Screen Printers (AREA)
- Printing Methods (AREA)
Abstract
A circuit board solder mask process relates to the technical field of circuit board manufacturing, and comprises the following steps: step one, solder resist pretreatment; step two, screen printing of a base material; carrying out substrate silk-screen printing by adopting first ink and a first dot screen printing plate; the first ink is prepared from thermosetting resin and hole plugging ink; step three, baking at high temperature; grinding the plate by using a sand belt; step five, the step one to the step four are circulated for a plurality of times; step six, performing finish oil silk-screen printing; adopting second printing ink and a second screen printing plate; the screen printing mesh number of the second dot screen printing plate is larger than that of the first dot screen printing plate; and seventhly, pre-baking, exposing, developing and baking at high temperature. According to the solder mask process, the first printing ink is combined with the first dot screen printing plate in the base material silk-screen printing, the oil feeding amount of the base material silk-screen printing each time is large, and the silk-screen printing efficiency is high; excessive diluent does not need to be added into the printing ink, so that the problem of silk-screen bubble is solved; and the surface oil silk screen printing adopts a second dot screen printing plate and second printing ink to ensure the surface quality.
Description
Technical Field
The application relates to the technical field of circuit board manufacturing, in particular to a circuit board solder mask process.
Background
In the manufacturing industry of printed circuit boards, a high-thickness copper circuit board cannot complete solder mask manufacturing in a solder mask silk-screen process due to the large drop characteristic between a copper surface and a base material surface, and particularly, the thicker the copper is, the harder the copper is to manufacture. The solder mask manufacturing can be completed by multiple screen printing in the solder mask screen printing process, but the solder mask manufacturing process has several problems: the problems of more pinhole bubbles, no oil dropping during silk printing, low efficiency of solder mask multiple silk printing and the like exist in the solder mask silk printing process.
The method is characterized in that a 40T or 36T screen printing plate is generally adopted for carrying out base material dot screen printing, and oil is difficult to drop in the screen printing process because the fall between a base material and a copper surface reaches 350UM during screen printing;
in contrast, some processes employ more diluents to further dilute the ink, thereby achieving the ink-bleeding effect. However, since the diluent is added too much, the diluent cannot be completely volatilized when the rest time and the prebaking time are insufficient, thereby causing generation of bubbles. In addition, the thickness of each screen printing is limited to about 40-60 mu m, so that the screen printing efficiency is low.
Disclosure of Invention
The technical problem that this application was solved is how to improve the current high thick copper circuit board hinder the welding process to oil difficulty, the easy bubble that exists, the inefficient defect of silk screen printing in the time of solving the silk screen printing.
In order to solve the above technical problem, an embodiment of the present application provides a circuit board solder mask process, including:
step one, solder resist pretreatment;
step two, screen printing of a base material; carrying out substrate silk-screen printing by adopting first ink and a first dot screen printing plate; the first ink is prepared from thermosetting resin and hole plugging ink; the proportion of the thermosetting resin to the hole plugging ink is 1: 1-7: 3;
step three, baking at high temperature;
grinding the plate by using a sand belt;
step five, the step one to the step four are circulated for a plurality of times;
step six, performing finish oil silk-screen printing; performing surface oil silk-screen printing by adopting second ink and a second dot screen printing plate; the number of the silk-screen meshes of the second dot screen printing plate is larger than that of the first dot screen printing plate;
and seventhly, pre-baking, exposing, developing and baking at high temperature.
In the technical scheme, further, before the screen printing of the substrate, the first ink is placed in a vacuum box to eliminate bubbles.
In the above technical solution, further, in the first ink, a ratio of the thermosetting resin to the hole plugging ink is 6: 4.
In the above technical solution, the first dot screen is an 18T screen, and the second dot screen is a 36T screen or a 43T screen.
In the technical scheme, furthermore, the process is suitable for products with the final surface copper thickness of 350 mu m, and the steps from one step to four times are circulated; in the base material in the first step, the thickness of the initial surface copper is larger than 360 mu m, and the line width on the base material needs to be compensated by 1mil on the basis of the original compensation value.
In the technical scheme, further, the thickness of the printing oil is more than 100 micrometers in each silk-screen printing of the base material.
In the above technical solution, further, the thickness of the copper on the damaged surface of the abrasive belt grinding plate at each time is 2 μm.
In the above technical solution, further, the sizes of the first dot screen and the second dot screen are increased by 3 mils on the basis of the substrate area of the product.
In the above technical solution, further, the thermosetting resin in the first ink is a transparent resin, and the color of the hole plugging ink is the same as that of the second ink.
Compared with the prior art, the technical scheme of the embodiment of the application has the following beneficial effects:
the embodiment of the application provides a circuit board solder mask process, which comprises multiple times of substrate screen printing and surface oil screen printing, wherein the substrate screen printing adopts first ink consisting of thermosetting resin and hole plugging ink combined with a first dot screen printing plate with a low screen printing mesh number, and the oil dropping amount of each time of substrate screen printing is very large, so that the overall screen printing efficiency is very high; moreover, the oil discharging effect is good, and excessive diluent does not need to be added into the printing ink, so that the problem of silk-screen bubble in the prior art is solved; in addition, the surface oil silk screen adopts a second dot screen printing plate with high silk screen mesh number, and the surface quality is ensured by combining the second printing ink required by customers.
Drawings
Fig. 1 is a schematic flow chart of a solder resist process of a circuit board according to an embodiment of the present application.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the present application are described in detail below with reference to the accompanying drawings. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.
The circuit board solder mask process belongs to one part of the whole PCB manufacturing process, and is particularly suitable for manufacturing a high-thickness copper circuit board needing multiple silk-screen printing.
The prior art PCB manufacturing process includes the following steps:
cutting → drilling → copper deposition → board → pattern transfer → pattern plating → alkaline etching → Chinese check → solder mask → text → tin spray → molding → electric test → final check → packaging.
Wherein, cutting → drilling → copper deposition → board electric → pattern transfer → pattern plating → alkaline etching → middle process; character → tin spraying → molding → electric testing → final inspection → packaging; the above-mentioned flow produces according to the management and control parameter of ordinary high thickness board, does not give unnecessary details in this application.
The solder resist process described above is explained below with reference to the drawings.
Fig. 1 is a schematic flow chart of a solder resist process of a circuit board according to an embodiment of the present application.
Referring to fig. 1, the solder mask process for a circuit board provided by the embodiment of the present application includes:
step one, solder resist pretreatment.
The pre-treatment of the solder mask comprises mechanical board grinding, which is used for removing an oxide layer on the copper surface of the circuit board before the solder mask is carried out, and cleaning the surface of the circuit board and roughening the copper surface, thereby enhancing the bonding force between the ink and the solder mask.
In the embodiment, the pretreatment speed is adjusted to 2m/min, and 100% drying after pretreatment of the product is fully ensured.
And step two, screen printing of the base material.
The base material silk screen printing adopts a first blocking point screen printing plate and first printing ink.
The first dot screen is a low-screen-mesh screen, for example: 18T screen printing plate. It should be noted that, when the first dot screen printing plate is designed, 3 MILs need to be increased on one side on the basis of the substrate area of the product, which is convenient for ensuring that the substrate surface is completely screen-printed in place.
The first ink was the new ink developed in this application and was formulated from a thermoset resin and a via-hole ink. Wherein the proportion of the thermosetting resin to the hole plugging ink is 1: 1-7: 3, particularly, when the ratio of the thermosetting resin to the hole plugging ink is 6:4, the oil feeding amount and the drying efficiency are optimal.
The thermosetting resin is transparent resin, the color of the hole plugging ink is consistent with that of the second ink used by the screen printing surface oil, and the color coordination of the whole ink can be ensured on the basis of ensuring the fluidity.
The ink is mixed with the hole plugging ink, so that the problem that pure thermosetting resin is difficult to remove due to high hardness after being baked at high temperature is solved, and the ink can be easily removed through an abrasive belt machine.
The low-screen-mesh printing ink has higher passing rate, and the printing ink with better fluidity is used, and the combination of the low-screen-mesh printing ink and the printing ink ensures that the oil dropping amount of each screen printing of the base material is very large, particularly, the thickness of the printing ink is more than 100 mu m; therefore, the overall screen printing efficiency is high.
And because the oil discharging effect is good, excessive diluent does not need to be added into the printing ink, and the technical defect of silk-screen bubble in the prior art is overcome.
In some embodiments, to further solve the problem of silk-screen bubbles, the first ink is placed in a vacuum chamber to eliminate bubbles before the substrate is silk-screened.
And step three, baking at high temperature.
And high-temperature baking is used for baking the silk-screen printing ink. In some embodiments, the baking sheet parameters are: 60min at 150 ℃.
And step four, grinding the plate by using a sand belt.
The ink permeating into the copper surface of the silk-screen substrate is completely removed, and the thickness of the copper on the damaged surface of the abrasive belt grinding plate is about 2 mu m each time.
And step five, circulating the step one to the step four for a plurality of times.
Because the copper surface and the base material surface have larger drop height characteristic, the high-thickness copper circuit board cannot complete solder mask manufacture by one-time solder mask in the solder mask silk-screen process, and can complete solder mask by multiple silk-screen processes.
For example, the process is suitable for products with the surface copper thickness of 350 μm, and the screen printing frequency of the base material with the surface copper thickness of 350 μm is controlled to be three times due to the fact that the thickness of the printing oil is larger than 100 μm each time, namely the circulation step one to the step four times; and performing surface oil silk-screen printing for the fourth time.
In the base material in the first step, the thickness of the initial surface copper is larger than 360 mu m, and the line width on the base material needs to be compensated by 1mil on the basis of the original compensation value.
And step six, performing finish oil silk printing.
And performing surface oil silk-screen printing by adopting second printing ink and a second dot screen printing plate, wherein the surface oil silk-screen printing comprises a copper surface and a base material surface.
The number of the screen printing meshes of the second dot screen is greater than that of the first dot screen, and is a high screen printing mesh number, for example: 36T screen or 43T screen. It should be noted that, as with the first dot screen, when designing the second dot screen, 3 MILs need to be increased on the basis of the substrate area of the product.
The second printing ink is the printing ink type specified by a customer, and the thickness and the surface quality of the printing ink can be ensured by combining a high-screen-mesh-number screen printing plate.
And seventhly, pre-baking, exposing, developing and baking at high temperature.
The steps in the step are carried out according to the production parameters of the surface oil, which belongs to the conventional technical means and are not repeated herein.
In addition, this application still relates to face copper and line width process loss precompensation value design:
the high-thickness copper product with the surface copper thickness of 350UM needs to be subjected to screen printing for multiple times, abrasive belt plate grinding treatment is needed before each screen printing, and then the circulation flow of resistance welding pretreatment → screen printing → post baking → abrasive belt plate grinding is carried out. The process can consume surface copper and line width, and in order to ensure the copper thickness and line width requirements of a customer product, the thickness and line width of the surface copper are pre-compensated on the basis of the customer requirements, the thickness of the surface copper needs to reach the copper thickness of more than 360 mu m after electroplating, and the compensation is carried out by 10 mu m on the basis of the customer requirements; the line width needs to be compensated by 1mil based on the original compensation value.
Although the present application is disclosed above, the present application is not limited thereto. Various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the scope or spirit of the present disclosure, and it is intended that the scope of the present disclosure be defined by the appended claims.
Claims (9)
1. A circuit board solder mask process is characterized by comprising the following steps:
step one, solder resist pretreatment;
step two, screen printing of a base material; carrying out substrate silk-screen printing by adopting first ink and a first dot screen printing plate; the first ink is prepared from thermosetting resin and hole plugging ink; the proportion of the thermosetting resin to the hole plugging ink is 1: 1-7: 3;
step three, baking at high temperature;
grinding the plate by using a sand belt;
step five, the step one to the step four are circulated for a plurality of times;
step six, performing finish oil silk-screen printing; performing surface oil silk-screen printing by adopting second ink and a second dot screen printing plate; the number of the silk-screen meshes of the second dot screen printing plate is larger than that of the first dot screen printing plate;
and seventhly, pre-baking, exposing, developing and baking at high temperature.
2. The circuit board solder mask process of claim 1, wherein the first ink is placed in a vacuum box to eliminate air bubbles before the substrate is screen printed.
3. The circuit board solder mask process of claim 1, wherein the ratio of thermosetting resin to via hole ink in the first ink is 6: 4.
4. The circuit board solder mask process according to claim 1, wherein the first dot screen is an 18T screen, and the second dot screen is a 36T screen or a 43T screen.
5. The circuit board solder mask process according to claim 1, wherein the process is applied to a product with a final surface copper thickness of 350 μm, and the steps are cycled for one to four times; in the base material in the first step, the thickness of the initial surface copper is larger than 360 mu m, and the line width on the base material needs to be compensated by 1mil on the basis of the original compensation value.
6. The circuit board solder mask process of claim 5, wherein the thickness of the printing oil is greater than 100 μm each time the substrate is screen printed.
7. Circuit board solder mask process according to claim 5 or 6, characterized in that the damaged surface copper thickness per sanding of the board is 2 μm.
8. The circuit board solder mask process according to claim 1, wherein the size of the first dot screen and the second dot screen is increased by 3mil on the basis of the area of the product substrate.
9. The circuit board solder mask process according to claim 1 or 3, wherein the thermosetting resin in the first ink is a transparent resin, and the color of the hole plugging ink is consistent with that of the second ink.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911296059.9A CN110944456A (en) | 2019-12-16 | 2019-12-16 | Circuit board solder mask process |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911296059.9A CN110944456A (en) | 2019-12-16 | 2019-12-16 | Circuit board solder mask process |
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| CN110944456A true CN110944456A (en) | 2020-03-31 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111867271A (en) * | 2020-07-21 | 2020-10-30 | 大连崇达电路有限公司 | Method for manufacturing variegated ink solder mask of thick copper plate |
| CN112672531A (en) * | 2020-11-30 | 2021-04-16 | 江门荣信电路板有限公司 | Double-sided processing method of PCB single-sided substrate |
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| CN111867271A (en) * | 2020-07-21 | 2020-10-30 | 大连崇达电路有限公司 | Method for manufacturing variegated ink solder mask of thick copper plate |
| CN112672531A (en) * | 2020-11-30 | 2021-04-16 | 江门荣信电路板有限公司 | Double-sided processing method of PCB single-sided substrate |
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Application publication date: 20200331 |