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The solder resist development process in the printed board is a relatively simple process among all processes of the printed board, but it also plays an important role. The solder resist development process controls the appearance of the printed board and the inside of the hole, and strives to make the "beautiful coat" of the printed board "the most beautiful", so as to make the printed board look more comfortable, protect and control the quality in the hole. The solder resist will not appear in the hole of the printed board to ensure the quality of the printed board. Therefore, the solder resist development process of the printed board is a very important process. The following will introduce the PCB solder resist development process and the solutions to the problems encountered.

印刷电路板中的阻焊显影工艺是在丝网印刷后用感光板覆盖印刷电路板上的焊盘，使其不会暴露在紫外线辐射下，紫外线辐射后阻焊保护层更牢固地附着在印刷电路板表面。焊盘不暴露在紫外线辐射下，因此在热空气整平过程中，铜焊盘可以暴露出铅和锡。

焊料掩模开发过程大致可分为三个操作步骤：

1.第一个程序是暴露。

First, check whether the polyester film and glass frame of the exposure frame are clean before exposure. If they are not clean, wipe them with an anti-static cloth in time. Then, turn on the power switch of the exposure machine, and then turn on the vacuum button to select the exposure procedure. Before formal exposure, the exposure machine can be "air exposed" for five times,The function of "air exposure" is to enable the machine to enter the saturated working state, and the most important thing is to make the energy of ultraviolet exposure lamp enter the normal range. Without "air exposure", the energy of the exposure lamp may not enter the best working state. During exposure, the printed board will have problems.The exposure machine enters the best working state. Before aligning with the photographic plate, check whether the quality of the plate is qualified.Check whether there are pinholes and exposed parts on the drug film surface on the base plate, and whether they are consistent with the graphics of the printed board, because this will check the photographic base plate, so as to avoid rework or scrapping of the printed board for some unnecessary reasons.

焊料掩模开发通常采用视觉定位，使用银盐基板，将基板的焊盘与印刷板的焊盘孔重叠对齐，并用胶带固定即可暴露。对齐过程中存在许多问题。例如，由于基板与温度和湿度等因素有关，如果温度和湿度控制不好，摄影基板可能会收缩或扩大变形。这样，在焊料掩模开发过程中，摄影基板与PCB焊盘并不完全一致。当基板减小时，请查看基板焊盘和印刷板焊盘之间的差异。如果差异很小，可以在热空气流平过程中施加铅和锡，那么就没有大问题，可以进行阻焊层开发。如果差异很大，只需再次复制，并尝试使底板垫重合。对齐前，注意基板的药物膜表面是否颠倒。在对齐过程中，确保药物膜表面朝下。如果面朝上，药物膜表面容易被划伤，导致基板暴露，使印刷板暴露部分存在耐焊性，这将严重造成印刷板的浪费。此外，还应该注意的是，有时化妆的底板会与印刷电路板的图形不一致。通常，化妆的底板会沿着化妆板的边缘切割，然后对齐后露出整个印刷板。在正式曝光和焊料掩模开发之前，应注意上述问题。

曝光前，检查印刷电路板是否被真空箱吸收。真空包层的压力应足够，无露水。如果暴露的空气会使紫外线沿着电路板侧面照射到图案中，导致遮光部分暴露，显影不会丢失。有时，它会暴露在一侧。在这种情况下，应使用黑布将一侧没有图案的一侧与曝光灯发出的紫外线隔开。如果不使用黑布，紫外线会通过没有图案的一侧进入焊盘，这样焊盘孔中的阻焊剂在曝光后就无法显影。当暴露两面图形不一致的印刷电路板时，先丝网印刷一面以防焊接，然后再暴露一面。显影后，在丝网印刷的另一面进行抗焊处理，因为如果两面同时进行丝网印刷和曝光，一侧会有更复杂的图形，需要屏蔽的焊盘更多，另一侧需要屏蔽的零件更少，这样紫外线就会从一侧照射到另一侧，遮光较多的一侧在紫外线照射后的显影过程中不会显示出来，这会导致返工或报废。在曝光过程中，丝网印刷后的印刷板在固化过程中没有干燥。在这种情况下，阻焊剂在对准过程中会粘在感光板上，印刷板也会被返工。因此，如果发现它没有干燥，特别是如果大多数印刷板没有干燥，应该在烤箱中再次干燥。这些情况都是暴露过程中容易出现的问题，所以我们应该仔细检查，及时发现并解决。

2.第二个过程是发展。

开发操作通常在开发人员中进行。通过控制显影剂温度、传输速度和喷雾压力等显影参数，可以获得更好的显影效果。开发是用开发溶液去除焊盘上的焊料电阻。用于显影的溶液是1%无水碳酸钠，液体温度通常在30至35摄氏度之间。在正式显影之前，应加热显影剂，使溶液达到预定温度，以达到最佳显影效果。显影机分为三个部分：第一部分是喷涂部分，主要使用高压注射无水碳酸钠来溶解未暴露的阻焊剂；第二部分是水洗部分。首先，使用高压泵清洗残留溶液，然后进入循环水进行彻底清洗；第三部分是干燥部分。干燥段前后有一个气刀，主要利用热风干燥板材。此外，如果干燥部分的温度很高，板也可以干燥。

The correct development time is determined by the development point. The development hard point must be kept at a constant percentage of the total length of the development section. If the development point is too close to the outlet of the development section and the unexposed solder resist layer is not fully developed, the residue of the unexposed solder resist layer may remain on the board surface. If the development point is too close to the inlet of the development section,The exposed solder resist layer may be etched and become hairy and lose luster due to long contact with the developer.Generally, the development point is controlled within 40% - 60% of the total length of the development section. In addition, it should be noted that it is easy to scratch the board during development. The usual solution is that during development, the board placing operator should wear gloves and handle the board gently. There are also different sizes of printed boards. Therefore, try to put the boards with similar sizes together. When placing the board,A certain distance shall be maintained between the boards to prevent the boards from being crowded during transmission, resulting in "jamming" and other phenomena.After the video is displayed, place the printed board on a wooden bracket.

3.第三道工序是补板。

修复电路板包括两个方面：一是修复图像的缺陷，二是去除与所需图像无关的缺陷。在修复板材的过程中，应注意戴旋转手套，防止手汗污染板材表面。常见的板材表面缺陷包括：漏印，也称为飞白、氧化、表面不平整、孔内电阻焊、图形有针孔、表面污垢、两侧颜色不一致、开裂、气泡和重影。在修改过程中，由于一些印刷电路板存在严重缺陷且无法修复，使用氢氧化钠水溶液加热并溶解原始阻焊层，然后在丝网印刷和曝光后进行返工。如果印刷电路板的缺陷很小，比如小铜点，可以用细刷仔细蘸取调整后的阻焊层。