There are many reasons for the overflow of FPC flexible circuit board, and FPC manufacturers process parameters, preservation environment, staff operation, coverlay processing process and other related.

Below, specific factors are discussed:

1. Reasons for parameters of coverlay in the manufacturing process

When CL enters drying stage after coating, improper control of temperature, time and other parameters will lead to excessive flow of glue system in the semi-curing process. In addition, if the distribution of CL adhesive coating is not uniform, it is difficult to control the amount of spilled glue in the pressing process.

2. Overflow of coverlay and storage environment reasons

Currently, the storage condition of coverlay is below 10℃, the optimal storage temperature is 0℃-5℃, and the storage time is 90 days. f the storage time is exceeded or the storage conditions are not up to the requirements, coverlay is prone to moisture absorption in the air, resulting in unstable glue system and easy to produce glue overflow.

3. Whether the customer’s product structure is reasonable is an important reason for the phenomenon of glue overflow

In the product design process, the collocation of FCCL and CL should be as reasonable as possible. If the thickness of coverlay adhesive system is far from the thickness of the substrate copper foil, there is a high possibility of adhesive overflow, so the mistake of FPC flexible circuit board structure collocation should be avoided at the source.

4. The special design of FPC flexible circuit board product can also lead to local adhesive overflow

With the emergence of high precision products, independent PAD bits are designed in some FPC flexible circuit board products.In the process of pressing and heating up, because there is no space around the PAD, the smaller the adhesive overflow phenomenon is more obvious.

5. Causes of adhesive overflow and process parameter setting of FPC flexible circuit board factory

In the setting of process parameters, if the pressure is too large, too long, the press pressure is not uniform may lead to adhesive overflow.In addition, the control of adhesive overflow is also related to the rubber absorption performance of the auxiliary materials used in hot pressing.

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