PCB Fabrication

Detailed explanation of PCB circuit board plugging process for you

by:A-TECH      2021-03-30
The vias play the role of interconnection and conduction of the lines. The development of the electronics industry also promotes the development of PCBs, and also puts forward higher requirements on the production process of printed boards and surface mount technology, and the plugging process has emerged. Now, let the engineer explain the PCB circuit board plugging process for you in detail: 1. After the hot air leveling, the plugging process adopts the non-plugging process for production. After the hot air leveling, the aluminum sheet screen or the ink screen is used to complete all the fortresses. Via hole plug hole. The process flow is: board surface soldering→hot air leveling→plugging→curing. This process can ensure that the through holes will not lose oil after the hot air is leveled, but it is easy to cause the plug hole ink to contaminate the board surface and uneven. 2. Hot-air leveling process for plugging holes 1. Plug the holes with aluminum sheet, solidify, and transfer the graphics after grinding the plate. This process uses a CNC drilling machine to drill out the aluminum sheet that needs to be plugged to make a screen and plug the holes. The process flow is: pre-treatment → plug hole → grinding plate → pattern transfer → etching → board surface solder mask. This method can ensure that the via hole plug is flat, and hot air leveling will not cause quality problems such as oil explosion and oil drop on the hole edge. However, this process requires one-time thickening of copper, which requires high copper plating on the entire board. 2. After plugging the hole with aluminum sheet, directly screen-print the surface of the board. This process uses a CNC drilling machine to drill the aluminum sheet that needs to be plugged to make a screen, install it on the screen printing machine for plugging, and park it for no more than 30 minutes. 36T silk screen directly screens the solder mask on the board surface. The process flow is: pre-treatment-plug hole-silk screen-pre-baking-exposure-development-curing. This process can ensure that the via hole cover oil is good, the plug hole is flat, and the via hole will not be tinned after hot air leveling, and the hole will not be hidden. Tin beads, but it is easy to cause solder pads on the ink in the hole after curing, poor solderability, etc. 3. Aluminum sheet plugging, developing, pre-curing, and grinding the board for the board surface solder mask with a CNC drilling machine, drilling out the aluminum sheet that requires plugging holes, making a screen, and installing it on the shift screen printing machine for plugging holes and plugging holes. It must be full, then cured, and polished for surface treatment. The process flow is: pre-treatment-plug hole-pre-baking-development-pre-curing-board surface solder mask. This process can ensure that the via hole will not lose oil or explode after hot air leveling, but the via hole contains tin beads and via holes The tin is difficult to completely solve. 4. The board surface solder resist and plug hole are completed at the same time. This method uses 36T (43T) screen, installed on the screen printing machine, using a backing plate or nail bed, while completing the board surface, plug all the through holes. The process flow is: pre-treatment-silk screen-pre-baking-exposure-development-curing. The process time is short and the utilization rate of the equipment is high. It can ensure that the via holes will not lose oil and the via holes will not be tinned after hot air leveling. However, due to the use of silk screens for plugging, a large amount of air is contained in the via holes, resulting in voids and unevenness. , There are a few via holes hidden tin. The above is the PCB circuit board plugging process that the engineer explained for you in detail. I hope it will be helpful to customers and friends.
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