CN110831332A

CN110831332A - Method for processing solder mask half plug hole

Info

Publication number: CN110831332A
Application number: CN201910995903.0A
Authority: CN
Inventors: 刘东虎; 冷亚娟; 郭明亮
Original assignee: JIANGSU BOMIN ELECTRONICS Co Ltd
Current assignee: JIANGSU BOMIN ELECTRONICS Co Ltd
Priority date: 2019-10-18
Filing date: 2019-10-18
Publication date: 2020-02-21

Abstract

The invention provides a processing method of a solder resist half plug hole, which comprises the following steps: and (3) plug hole printing: solder resist ink plug holes are formed in the through holes of the PCB with the through holes through copper surface printing, the through holes are filled with the solder resist ink, and the through holes are filled with the solder resist ink in a plug hole mode. And (3) hole filling exposure: and carrying out single-side exposure on the solder resist ink at the plug hole. Hole plugging development: and developing the plug hole to ensure that the plug hole windowing surface is free from residual development and the depth of the ink in the plug hole is as large as possible, wherein the plug hole is in a half plug hole state. And (3) hole plugging and curing: and drying the half plug holes at high temperature to solidify the half plug holes. Processing the surface oil: and sequentially performing cleaning treatment → printing → drying → exposing → developing → curing and baking on the PCB with the cured semi-plug holes. The semi-hole plugging ink and the copper surface ink both need to use photosensitive ink, unexposed ink developer can be cleaned, and the problem that the surface ink cannot be cleaned cleanly due to the fact that the developing amount is reduced during hole plugging development is solved.

Description

Method for processing solder mask half plug hole

Technical Field

The invention belongs to a processing method of a solder mask half plug hole, and particularly relates to a processing method of a solder mask half plug hole capable of realizing that the depth of the half plug hole is more than 50% of the total plate thickness

Background

Solder tends to flow to the back surface through the through holes of the PCB during the manufacturing process of the PCBA, which causes poor short circuit, and filling the through holes with solder resist ink during the manufacturing process of the PCB for preventing short circuit is called plug holes. When solder resist ink is printed and filled, the copper surfaces of the two sides of the PCB in the through hole and the hole opening are covered with ink, and the copper surfaces of the two sides of the hole opening are not required to be packaged and completely exposed when exposure processing is carried out subsequently, and the copper surfaces of the two sides of the PCB in the through hole and the hole opening are covered with ink to form a plug hole after development. However, one copper surface of part of the hole opening of the through hole does not need to be packaged, and the other copper surface of the hole opening of the through hole needs to be packaged, ink is not allowed to cover the copper surface on one side of the hole opening of the through hole, the copper surface is called half hole plugging, the ink on the single copper surface cannot be exposed during exposure, and liquid medicine reacts with the ink in the hole during development, so that few ink is plugged in the hole. When customers require that the depth of the hole plugging ink in the half-plug hole is more than 50% of the total plate thickness, poor development of the copper surface ink can be caused due to reduction of the development amount, and the mode of exposing and developing the hole plugging ink and the copper surface ink together is difficult to realize.

Disclosure of Invention

The invention aims to provide a method for processing a solder resist half plug hole, which can realize that the depth of the half plug hole is more than 50 percent of the total plate thickness.

According to one aspect of the invention, a method for processing a solder resist half plug hole is provided, which comprises the following steps

And (3) plug hole printing: solder resist ink is printed at the through hole of the PCB with the through hole to plug the through hole through a copper surface, the through hole is filled with the solder resist ink, and the state that the through hole is filled with the solder resist ink is the plug hole;

and (3) hole filling exposure: performing single-side exposure on the solder resist ink at the plug hole;

hole plugging development: developing the plug hole to ensure that the plug hole windowing surface is free from residual development and the depth of the ink in the plug hole is as large as possible, wherein the plug hole is in a half plug hole state;

and (3) hole plugging and curing: drying the half plug holes at high temperature to solidify the half plug holes;

processing the surface oil: and sequentially performing cleaning treatment → printing → drying → exposing → developing → curing and baking on the PCB with the cured semi-plug holes.

In some embodiments, the solder resist ink protruding from the PCB board comprises edge copper face ink at the periphery and plug hole inner ink at the middle part,

the edge copper surface ink protrudes out of the PCB board thickly and is not more than 30um, and the height difference between the ink in the plug hole and the ink on the edge copper surface of the plug hole is not more than 20 um.

In some embodiments, the PCB board is subjected to a cleaning process before the receptacle is printed and the PCB board is subjected to a pre-bake drying process after the receptacle is printed.

The beneficial effects are as follows: photosensitive ink is required to be used for both the semi-hole plugging ink and the copper surface ink, unexposed ink developing solution can be cleaned, and the problem that the surface ink cannot be cleaned cleanly due to the fact that the developing amount is reduced during hole plugging development is solved;

according to the invention, the semi-hole plugging ink is independently processed, the copper surface ink is processed after the development amount is reduced, and the processing of the product with the hole plugging depth of more than 50% is realized under the condition of ensuring the quality safety;

the invention realizes that the depth of the half plug hole is more than 50 percent of the total plate thickness under the condition of not influencing the quality of the copper surface.

Drawings

Fig. 1 is a schematic structural diagram of a PCB board with a via hole prepared by a method for processing a solder resist half via hole according to an embodiment of the present invention;

FIG. 2 is a schematic view of preparing half via holes by exposing the via holes of the PCB of FIG. 1;

FIG. 3 is a schematic view of preparing half via holes by exposing the via holes of the PCB of FIG. 1;

FIG. 4 is a schematic structural diagram of a PCB with half via holes prepared by a method for processing solder resist half via holes according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a surface oil processed PCB board with half via holes prepared by a method for processing solder resist half via holes according to an embodiment of the present invention.

Detailed Description

The invention is further described with reference to the following figures and specific embodiments.

The invention provides a processing method of a solder resist half plug hole, which comprises the following steps:

step one, hole plugging printing. As shown in fig. 1The method specifically comprises the following steps: firstly, cleaning the PCB 1 with the through hole 11, printing solder resist ink on the through hole 11 of the PCB 1 with the through hole 11 through the copper surface 12 to fill the through hole 11 with the solder resist ink, wherein the state that the through hole 11 is filled with the solder resist ink is the plug hole 21. During printing, printing parameters are adjusted according to the aperture of the plug hole 21 and the thickness of the PCB 1, and the required ink amount of the plug hole 21 is different according to the aperture of the through hole 11 and the thickness of the PCB 1, so that the ink amount of the plug hole 21 is required to be adjusted according to the specification of an actual product in the step. In this embodiment, the plug holes 21 print parameters: the aperture of the through hole 11 is 0.3mm, the plate thickness is 1.2mm, the angle of the scraper and the ink covering knife is 20 degrees, the speed of the scraper and the ink covering knife is 4 grids, and the pressure of the scraper and the ink covering knife is 4kg/cm²The temperature in the drying parameters of the plug hole 21 is 72 +/-2 ℃, and the time in the drying parameters of the plug hole 21 is 23 min. And (5) carrying out pre-baking drying after printing is finished. The solder resist ink protruding from the copper side 12 of the PCB 1 comprises the edge copper side ink at the periphery and the inner ink of the plug hole 21 at the middle. The height 32 of the edge copper surface ink which protrudes out of the copper surface 12 of the PCB 1 is not more than 30um, and the height difference 31 between the ink in the plug hole 21 and the edge copper surface ink of the plug hole 21 is not more than 20 um. The standard can be properly relaxed when the requirement of the customer specification is looser, and the requirement of the solder mask windowing surface can be properly relaxed when the whole board surface single-side plug hole 21 is processed.

Step two: and exposing the plug holes. Specifically, the solder resist ink in the via hole 21 provided with the half via hole is exposed on one side, as shown in fig. 2 and 3, and the direction indicated by the arrow in fig. 2 and 3 is the exposed side. The exposure diameter is set according to the aperture of the PCB 1 and the exposure alignment precision, the whole exposure in the aperture range is controlled, and the quality is poor easily due to dislocation exposure. If the exposure alignment accuracy is + -40 um and the aperture is 250um, at least 330um of the exposure spot diameter and the hole form a concentric circle. In an actual product, there may be a plurality of apertures and different production equipments have different exposure accuracies, so that the exposure diameter needs to be set according to actual specifications and processing capabilities. In this example, the exposure spot diameter is 0.4mm and the exposure energy is 9-10 grids.

Step three: and developing the plug holes. Specifically, the half via holes 22 are developed to increase the line speed of development, reduce the spray pressure, and the like, and if necessary, reduce the concentration of the developing solution,the development of the copper surface of the windowing surface of the half plug hole 22 is controlled to be free from residue, the depth of the ink in the plug hole 21 is as large as possible, and the plug hole 21 is in a half plug hole 22 state. The product specification is that the depth of all hole plugging holes is more than 50%, and one product is provided with tens of thousands of holes, because the final depth of each hole has certain difference due to the difference of the amount of liquid medicine entering each hole during processing, the deeper the hole plugging depth is required to reach 50%, the better the hole plugging depth is, and the upper limit is certainly not more than the total plate thickness of 33. The total thickness 33 includes the thickness of the PCB board and the thickness of the ink on both surfaces of the PCB board 1. The half via thickness 34 is the distance between the lowest point of the side of the via hole 21 where the half via hole 22 is developed and the lowest ink surface of the PCB board 1 where the via hole 21 is not developed. In this embodiment, all of the hole plugs have a hole depth of 70% or more. The development parameters were as follows: the developing speed is limited to 5m/min, the concentration of developing solution NaCO3 is 1%, the pH value is 10-11, and the spray pressure is 0.25kg/cm²。

Step four: and (5) solidifying the plug holes. Specifically, the half via holes 22 are baked and cured at a high temperature, so that the solder resist ink cannot be developed by the developer after being cured. The curing parameters of the plug hole are as follows: 30min at 70 +/-5 ℃, 30min at 90 +/-5 ℃, 30min at 135 +/-5 ℃ and 60min at 155 +/-5 ℃. The PCB board with half-plugged holes processed in the second step, the third step and the fourth step is shown in FIG. 4.

Step five: and (5) processing the surface oil. Under normal conditions, the PCB 1 needs surface oil to block the position where elements are not needed to be mounted and plugged, so as to prevent tin-sticking short circuit, namely a solder mask; the individual PCB boards 1, which are simple or do not require component mounting, do not require solder resist. The surface oil processing step comprises the following steps of processing the PCB 1 with the half plug hole 22 cured and completed according to the following procedures: cleaning treatment → printing → drying → exposure → development → curing and baking. The oil-surfaced PCB board with half-tap holes is shown in fig. 5.

The above description is further illustrative of the present invention with reference to specific preferred embodiments, and it is not to be construed that the present invention is limited to the specific embodiments. Meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, which are within the protection scope of the present invention.

Claims

1. A processing method of a solder resist half plug hole is characterized by comprising

2. The method for processing solder mask half via hole as claimed in claim 1, wherein the solder mask ink protruded from the PCB board includes edge copper face ink at the periphery and via hole inner ink at the center,

3. The method of processing solder mask half via hole as claimed in claim 1, wherein said PCB board is cleaned before printing via hole and said PCB board is pre-baked and dried after printing via hole.