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1 Production process
The three types of resin plug holes introduced have different processes, which are as follows:
1.1 POFV type products (different PCB factories have different equipment and different processes)
Grinding process:
1. Cutting - buried hole inner layer pattern - AOI - pressing - drilling - PTH/plating - plugging - baking - grinding - inner circuit - browning - pressing - drilling (laser drilling / mechanical drilling) -PTH/Plating-Outer layer circuit-Soldering-Surface treatment-Forming-Electrical measurement-FQC-Delivery
2. Cutting à buried hole inner layer graphics à AOI à pressing à drilling à copper sinking à board electrical à board electrical (thickened copper) à resin plug hole à polishing à inner layer graphics à AOI à pressing à drilling through hole à sinking copper à Board electrical à outer layer graphics à graphic plating à etching à solder mask à surface treatment à forming à electrical testing à FQC à shipment
No grinding: cutting material-buried hole inner layer pattern-AOI-pressing-drilling-PTH/electroplating-inner circuit-browning-plugging-flattening-baking-pressing-drilling (laser drilling/mechanical Drilling)-PTH/Plating-Outer circuit--Soldering mask-Surface treatment-Forming-Electrical measurement-FQC-Delivery
1.3, Type of resin plug hole of PCB outer through hole
1. Cutting - drilling - PTH/plating - plugging - baking - grinding - baking - outer circuit - solder mask - surface treatment - forming - electrical measurement - FQC - shipment
2. Cutting à drilling à sinking copper à board electrical à board electrical (thickened copper) à resin plug hole à baking - grinding - baking à outer layer graphics à graphic electroplating à etching à solder mask à surface treatment à forming àElectrical measurementàFQCàshipment
2 Special places in the process
l. From the above process, we obviously find that the process is different. In general, our understanding is that the "resin plug hole" is followed by the product of the process of "drilling through holes and copper plate electricity", and we all consider it to be a POFV product; if the "resin plug hole" is followed by the process "internal" Layer graphics", we consider it to be the inner HDI resin plugging product; if the "resin plugging" is followed by the "outer layer graphics";
l. The above different types of products are strictly defined in the process, and you cannot go through the wrong process; Keding Chemical has developed three different inks based on the characteristics of the above three processes, TP-2900S\TP-2900\TP-2900C These three inks correspond to the above three processes.
3 Process improvement
A. For products with resin plug holes, in order to improve the quality of the products, people are also constantly adjusting the process to simplify his production process and improve its production yield;
B. Especially for products with inner HDI plug holes, in order to reduce the scrap rate of the inner circuit opening after grinding, people adopt the process of plugging the holes after the circuit. The resin is pre-cured, and then the resin is cured using the high temperature of the pressing stage.
C. At the beginning, for the inner HDI plug hole, people used UV pre-cured + thermosetting ink. At present, thermosetting resin is directly selected, which effectively improves the inner HDI resin. The thermal performance of the plug hole.
4 Process method of resin plug hole
4.1 Ink used in resin plug hole
A. At present, there are many types of inks used in the resin plugging process in the PCB market.
4.2 Process conditions of resin plug hole
A. There are tens of thousands of holes in the resin plug hole, and it must be ensured that no hole is not full. This one in ten thousand defect will lead to the chance of scrapping, which will inevitably require rigorous thinking and standardization in the process.
B. Good plugging equipment is an inevitable requirement. Screen printers currently used for resin plugging can be divided into two categories, namely vacuum plugging machines and non-vacuum plugging machines.
4.3 Hole plugging process of ordinary screen printing machine
A. The selection of the screen printing machine is important to consider the maximum cylinder pressure, the way of lifting the net, the stability and levelness of the tool holder, etc.;
B. The squeegee for silk screen printing needs to use a squeegee with a thickness of 2CM and a hardness of 70-80 degrees. Of course, it must be resistant to strong acids and alkalis;
C. Screen printing can choose screen or aluminum sheet; what needs to be controlled is to select the appropriate number of screen meshes and the size of the window for the aperture according to the requirements of the plugging process conditions;
D. There are many kinds of pads used in resin plug holes, but they are often ignored by engineers. The backing plate not only plays a role of guiding air, but also plays a role of support. For the area with dense holes, after we drill the backing plate, the entire area is empty. At this position, the backing plate will bow or deform, and the support force for the plate is the worst, which will cause the hole to be plugged in this position. The plumpness is poor. Therefore, when making the backing plate, to find a way to overcome the problem of large-area vacancies, the best way at present is to use a 2mm thick backing plate and only drill 2/3 of the depth of the backing plate.
E. In the printing process, the most important thing is to control the printing pressure and speed. Generally speaking, the larger the aspect ratio, the smaller the aperture, the slower the required speed, and the greater the pressure requirement. Controlling a slower speed has the best effect on the improvement of plug-hole bubbles.
4.2 The plugging process of the vacuum resin plugging machine
Due to the high price of the vacuum resin plugging machine and the confidentiality of its equipment use and maintenance technology, there are only a handful of PCB manufacturers that can use this technology.
The plugging technology of the VCP vacuum resin plugging machine is mainly that it has an ink clamp and two plug-controlling heads that can move horizontally. There are many small holes in the plugging head. After the equipment is vacuumed, use a piston to push the ink in the ink clamp to the small hole in the plug hole. The two traverse plug holes first clamp the board, and then fill the ink through the many small holes in the plug hole Through holes or blind holes on the board. The board is hung vertically in the vacuum chamber, and the traverse plug hole head can be moved downwards until the holes in the board are filled with resin. The pressure of the plug head and ink can be adjusted to meet the requirements of plug hole fullness. Different board sizes can use different size plug heads to plug holes. After the plug hole is completed, the plug hole ink can be scraped off with a doctor blade and then added into the plug hole ink clip for reuse.
