CN-122028320-A - PCB same-surface solder mask method for preventing solder mask bridge defects

CN122028320ACN 122028320 ACN122028320 ACN 122028320ACN-122028320-A

Abstract

The invention discloses a PCB same-surface solder mask method for preventing solder mask bridge defects, which relates to the field of PCB processing, and comprises the steps of firstly coating solder mask ink on the surface of a PCB to form an ink layer containing solder mask bridge and a bonding pad area; covering the first film to leak out the solder resist bridge area and shielding the other areas, enabling the ink in the area to be solidified to form a solder resist bridge by high-parameter first exposure, covering the second film to leak out the area except the solder resist bridge and the bonding pad and shielding the two areas, enabling the ink in the area to be solidified by lower-parameter second exposure, and finally developing and washing out the uncured ink in the bonding pad area to leak out of the bonding pad. The method ensures that the solder resist bridge is fully cured, avoids bridge white and bridge dropping defects, prevents excessive curing of the printing ink at the windowed edge of the bonding pad, avoids the size reduction of the windowed window, ensures the welding precision, effectively reduces the PCB defective rate and improves the yield.

Inventors

DENG WEN
CHEN LIANGFENG
HU BIN
Jiang minquan

Assignees

珠海市龙昌电路科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260212

Claims (6)

1. A PCB same-surface solder mask method for preventing solder mask bridge defects is characterized by comprising the following steps: An ink coating, wherein a solder resist ink is coated on the surface of the PCB to form an ink layer, and the ink layer is provided with a solder resist bridge area and a bonding pad area; covering a first film, namely covering the first film (100) on the ink layer to leak the ink layer at the solder mask bridge area and shielding other areas of the ink layer except the solder mask bridge area; Exposing for the first time, exposing the PCB by adopting a first exposure parameter, and curing the ink layer at the solder mask bridge area and forming a solder mask bridge; A second film coating, wherein a second film (200) is coated on the ink layer to leak other areas of the ink layer except the solder mask bridge area and the bonding pad area and to shield the ink layer at the solder mask bridge area and the bonding pad area; Performing exposure treatment on the PCB by adopting a second exposure parameter, wherein the second exposure parameter is lower than the first exposure parameter, and only curing other areas of the ink layer except the solder resist bridge area and the bonding pad area; And developing, namely washing out the uncured ink layer at the pad area to leak out the pad.
2. The method of claim 1, wherein the first film (100) includes a first light-transmitting region (110) and a first light-shielding region (120), the first light-transmitting region (110) is used for leaking the ink layer at the solder bridge region, and the first light-shielding region (120) is used for shielding other regions of the ink layer except the solder bridge region.
3. The method of claim 1, wherein the second film (200) includes a second light-transmitting region (210), a second light-shielding region (220), and a third light-shielding region (230), the second light-transmitting region (210) is used for leaking out other regions of the ink layer except the solder bridge region and the pad region, the second light-shielding region (220) is used for shielding the ink layer at the solder bridge region, and the third light-shielding region (230) is used for shielding the ink layer at the pad region.
4. The method for preventing defects of solder mask bridges on a PCB of a same-surface solder mask as set forth in claim 1, wherein a pretreatment is further provided before the ink is applied, and the pretreatment is to remove an oxide layer on the surface of a copper layer on the surface of the PCB.
5. The method for preventing the defects of the solder mask bridge from being welded on the same surface of the PCB according to claim 1, wherein a pre-baking step is further arranged between the ink coating step and the first film-covered sheet, and the pre-baking step is to bake the PCB so as to enable the ink layer to be in a semi-cured state.
6. The method of claim 1, wherein a solder mask inspection is further performed after the developing, and the solder mask inspection is performed to inspect solder mask conditions on the surface of the PCB.

Description

PCB same-surface solder mask method for preventing solder mask bridge defects Technical Field The invention relates to the technical field of PCB processing, in particular to a PCB same-surface solder mask method for preventing solder mask bridge defects. Background In the manufacturing process of a high-precision PCB (printed circuit board), a solder mask bridge and a bonding pad are designed on the same surface at the same time, wherein the bonding pad is of a solder mask windowing structure with smaller size, the solder mask bridge is used for separating adjacent bonding pads to avoid short circuit during welding, and the bonding pad is used for realizing accurate welding with pins of components. In the exposure link of the solder mask process, in order to prevent bridge white phenomenon (namely, the unstable state of the bottom of the solder mask bridge is suspended and the bridge is endangered) and bridge dropping defect of the solder mask bridge, the solidification of the solder mask bridge is ensured to be firm, a higher-energy exposure process is usually adopted in the industry, but the design size of a bonding pad is smaller, the higher-energy exposure is easy to cause the problem of poor exposure, so that the windowing size of the bonding pad is reduced, in particular, when the exposure energy is too high, the solder mask ink at the windowing edge of the bonding pad is excessively exposed and solidified, the solidification range exceeds the design windowing boundary, the part of excessively solidified ink cannot be dissolved by developing liquid in the development stage, the actual windowing size of the bonding pad is smaller than the design size, the requirement of the size of welding of a component cannot be met, and finally the reject ratio of a PCB product is increased. Disclosure of Invention The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, the invention provides the PCB same-surface solder mask method for preventing the solder mask bridge defects, which is beneficial to improving the yield of PCB products. The PCB same-surface solder mask method for preventing solder mask defects comprises the steps of coating ink, coating solder mask ink on the surface of a PCB to form an ink layer, covering the ink layer with a solder mask area and a bonding pad area, covering the ink layer with a first film to leak the ink layer at the solder mask area and shield other areas except the solder mask area, exposing the PCB with a first exposure parameter, curing the ink layer at the solder mask area and forming a solder mask, covering the ink layer with a second film to leak the ink layer except the solder mask area and the bonding pad area, exposing the ink layer with a second exposure parameter, wherein the second exposure parameter is lower than the first exposure parameter, curing the ink layer at the solder mask area and the bonding pad area, and exposing the PCB with a second exposure parameter, and curing the ink layer except the bonding pad area and the bonding pad area. Has at least the following beneficial effects: When the same plate surface of the PCB is required to be subjected to solder resist processing, an ink coating step is firstly carried out, solder resist ink is uniformly coated on the plate surface of the PCB to form an ink layer which covers the plate surface of the PCB and comprises a solder resist bridge area and a bonding pad area, then a first film covering step is carried out, a first film is covered on the ink layer of the plate surface of the PCB, the solder resist bridge area on the ink layer is exposed, all other areas except the solder resist bridge area on the ink layer are shielded, then a first exposure step is carried out, the PCB is subjected to exposure processing by adopting a first exposure parameter, exposure light can only irradiate the ink layer at the solder resist bridge area due to the shielding effect of the first film, and then the ink layer at the area is only solidified and forms a firm solder resist bridge, and then a second film covering step is carried out, the second film is covered on the ink layer of the PCB, other areas except the solder resist bridge area and the bonding pad area in the ink layer are exposed, the ink layer is shielded, the two areas are shielded, the exposure is carried out, the second exposure step is carried out, the whole area is not exposed, and the whole area is exposed by the second film is subjected to exposure processing by adopting the second exposure parameter, and the whole exposure step is carried out, and the whole exposure processing is carried out, except the area is carried out by the second exposure parameter, and the exposure mask layer. The method has the advantages that the film is covered twice and different exposure parameters are adopted for carrying out regional exposure, the first exposure adopts the higher first exposure parameters to specially