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Cause Analysis and Solution of PCB Bending Warp after Pressing

Published:

2022-11-23 15:36

The bending and warping of vacuum laminator after PCB pressing is a common problem in the production of various manufacturers. Now we will make a detailed analysis on this problem

 

Defect name

Form of expression

Reason

Resolvent

WARP&TWIST

Overall bending/unevenness of pressing plate rear plate

1. The cold pressing speed is too fast, and the cold pressing is not pressurized.

2. The curing time is insufficient, and the board is not fully cured.

3. The lay up structure is asymmetric.

4. The cutting direction of the prepreg and the inner sheet is asymmetric.

5. The design of the board is asymmetric.

6. The temperature of the plates near the top and bottom layers of PLATEN changes too fast, and the internal stress is large when the resin is cured, which is easy to cause plate warping.

1. Cool to 50C under pressure, and keep the cooling rate of about Tg at 8-12C.

2. Extend the CYCLE time of the pressing plate to fully cure the reaction.

3. When arranging the plates, the semi curing sheet shall be placed symmetrically, and the symmetric semi curing sheet shall be consistent in longitude and latitude. 4. Ensure that the cutting direction is consistent with the prepreg.

5. The wiring density shall be uniform and symmetrical. The stress distribution is even when the resin is cured.

6. Increase the paper cover, delay the heating rate close to the level of PLATE, and reduce the number of plates in each OPENING.

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