Pcb board industry about pcb board resin plug hole and cover green oil selection?
1: The PCB industry is a headache. Customers often design green oil on the VIA hole without opening the window or partially opening the green window or opening the VIA hole on one side of the window. How to deal with this design?
Solution: First consider what surface treatment the PCB uses. In the case of tin-spraying (HALS), the single-sided plugging process must be avoided, the depth of the one-sided plugging hole is low, and the solder balls are easily clogged when the tin is sprayed. Seychelles has a great influence on the appearance.
If it is another surface treatment, such as Shen Jin, OSP, Shen Yin, etc., it can accept one side. After considering the above factors, check the customer's green window design. If it is partially open, it should be avoided as much as possible to cover the edges of the holes with green oil and allow green oil to enter the holes. This method is also prone to clogging the tin beads.
In combination with the above two cases, the best treatment is a double-sided plug hole or a green oil cap hole, and the side allows the treatment of 1-2 MIL tin ring to be the most popular among PCB manufacturers. Of course, the oil plugging situation here is for ordinary photographic oils rather than heat curing oils.
2: When the green oil of the PCB board is opened, it is usually prescribed that the green oil cannot enter the through hole. However: the green oil plug requires green oil to enter the hole. Do you have any questions about this?
Solution: Green oil window (mainly used for surface mount pad parts and plug holes, mounting holes, test points, etc., then green oil can not cover the pads and holes, because green oil is not conductive, if entering the hole This can lead to poor soldering and poor detectability).
Method A: If you want to make a good PCB board, the via surface of the via, the hole, and other parts of the pad are sprayed with tin (or other surface process), then you need to deal with the solder when processing data. When the window is opened, the conduction performance of the PCB through-hole is relatively strong.
Method B: If the density of the PCB board is very large, the via hole is required to be plugged, that is, the hole arm of the via hole is filled with green oil, and the surface is completely filled. This reduces the occurrence of short-circuiting of the board during the soldering process.
Method C: The silk screen printing is of course required to be strict. If it is pressed onto the pad to be soldered, the stability of the board cannot be guaranteed when the PCB board is soldered.
3: What should be the plug hole standard for BGA package parts on the board? Basically, it is necessary to do the plugging process, and of course there is no need to plug the hole. I don't know when to plug holes, when can I not plug holes, tangled!
Solution: A via that is very close to the pad or a via with a high density (size less than 0.4mm, usually 0.3/0.25mm is more common). To prevent the board from being short-circuited, such a board requires a plug hole. Processed.
Vias at the bottom of the BGA chip: If it is not a functional test point, it is a board that needs to be plugged, which also prevents the board from short-circuiting and easy to appear. If it is a functional test point for the board, you can open the window with the bot surface, and open a small window or green oil cover on the top surface. (When the pitch of bga is relatively large, the test point of the board is recommended to open a relatively small window. When the pitch is less than 1mm, it should be covered with green oil).
The above content is hoped to help the engineers and friends who are engaged in electronic design.
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