The reason for the problem of development is not clean and has Residual glue in FPC?

How to deal with these situation?

  1.  How to deal with these situation?There have glue mark and greasy dirt on the boards in prepared processing stage, it need to clean the plate thoroughly.
  2. The temperature is too high and time is too long in the stage of Pre-heating, so it need to control the temperature of the pre-drier, adjust it on normal temperature and strengthen the control of time.
  3. The exposure energy is too high on the stage of exposure, or the shading rate is poor of the base boards.
  4. The developing liquid’s concentration and the temperature are too low, so it need to check the concentration and adjust the temperature to normal timing.

FPC Typical Production Process

FPC Typical Production Process

Cutting -> NC Drilling -> Black Holes/Cu Plating -> D/F Lamination -> LDI Exposure ->Develop/Etch/Stripping -> Automatic Optical -> CVL Lay UP -> CVL Lamination -> Hole Punching -> Surface Treatment -> Screen Printing -> Open/Short Testing -> Adhere Stiffener -> Outline Punching -> Final Inspection

FPC Typical production process flow chat

FPC Typical production process flow chat

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Differences between Roll Anneal Copper Foil and Electrolysis Deposition Copper Foil

Differences between Roll Anneal Copper Foil and Electrolysis Deposition Copper Foil

Roll Anneal Copper Foil (RA copper):

Formation: Roll copper block many times, and then do the annealing treatment with high temperature. The shape of its crystal is lamellar structure.
Advantage: Soft, smooth surface, suitable for flexible PCB and small lines.
Shortage: high cost

Electrolysis Deposition Copper Foil (ED copper):

Formation: Melt copper into dilute sulfuric acid, it becomes bluestone solution.
Through a high electric field, copper attach on the metal drum. With the rolling of metal drum, thin copper foil finally formed.

Advantage: Low cost
Shortage: Unsuitable for small lines; bad bending resistance.
Here is the cross section observation of RA Copper and ED Copper:

roll anneal copper foil and electrolysis deposition copper foil