Some suggestions for LCD module FPC

First, the design aspect

1. Line: Since FPC will expand due to temperature and pressure during ACF crimping, it is necessary to consider the expansion ratio of the crimping finger when designing the line, and perform pre-compensation processing;

2. Typesetting: Design products should be distributed symmetrically throughout the layout as much as possible. The minimum interval between every two PCS products should be more than 2MM. The copper-free parts and the dense parts of the vias should be staggered as much as possible. These two parts are in the subsequent manufacturing process. Two important aspects that are affected by the ups and downs of materials.

3. Material selection: The glue of the cover film should not be thinner than the thickness of the copper foil, so as to avoid deformation of the product due to insufficient glue filling during the pressing, and the thickness and uniform distribution of the glue are the main culprit for the expansion and contraction of the FPC material.

4. Process design: The cover film should cover all the copper foil parts as much as possible. It is not recommended to cover the film to avoid uneven stress during pressing. The PI reinforcing surface adhesive of 5 MIL or more should not be too large. If it is unavoidable, it will be After the cover film is pressed and baked, the PI reinforcement is pressed and pressed.

Second, material storage

I believe that the importance of material storage does not need to be said more. It needs to be stored strictly in accordance with the conditions provided by the material supplier. The cold storage is not sloppy.

Third, manufacturing aspects

1. Drilling: It is best to add baking before drilling to reduce the increase and decrease of the substrate during subsequent processing due to the high moisture content in the substrate.

2. In electroplating: it should be made with short-side splint, which can reduce the deformation caused by the water stress caused by the swing. The swinging energy can be reduced during electroplating to minimize the amplitude of the swing. The number of splints also has a certain relationship. The number of asymmetric splints It can be assisted by other side materials; when plating, it can be charged and lowered to avoid the impact of sudden high current on the board, so as not to adversely affect the plating of the board.

3. Pressing: The traditional press machine is smaller than the fast press. The traditional press is thermostatically cured, and the fast press is heat-cured. Therefore, the change of the traditional press control glue should be stable. Of course, the laminated plate is also A very important part.

4. Baking: For fast-pressing products, baking is a very important part. The baking conditions must be such that the glue is completely cured, otherwise it will be infinite after subsequent production or use; the baking temperature curve is generally gradually increased to The temperature at which the glue is completely melted, and this temperature is continued until the glue is completely cured, and then gradually cooled down.

5. Try to maintain the stability of temperature and humidity in all stations during the production process. The transfer between the stations, especially those that need to be made outside, the conditions for product storage should be paid special attention.

Fourth, packaging aspects

Of course, the completion of the product is not to say that everything is fine. It is necessary to ensure that the customer does not have any problems in the subsequent use. In packaging, it is best to bake first, and then dry the moisture absorbed by the substrate during the manufacturing process. Vacuum packaging and instruct customers how to save.

Therefore, it is necessary to ensure that the quality of such products needs to be strictly in accordance with specific requirements from material preservation → process control → packaging → customer use.

The above is only my glimpse, and I hope everyone can correct me!

) Bending area line: a) There must be no through hole in the bent part; b) Protect the copper wire on the most sides of the line. If the space is insufficient, choose to protect the copper wire at the inner R angle of the bent part. c) The connecting part of the line needs to be designed as an arc.

4) Air gap: The bending area needs to be layered, and the glue is removed to facilitate the dispersion of stress. The bent area does not affect the assembly, the bigger the better.

5) Shielding layer: At present, the shielding layer of mobile phone is generally made of silver paste and copper foil, and the Japanese mobile phone has silver foil. a) The silver paste shield layer is used to reduce the actual number of layers of the movement, which is easy to assemble, simple in process and low in cost. However, because the silver paste is a mixture, the resistance is high, about 1 ohm. Therefore, it is not possible to directly design a layer of silver paste for grounding. b) Copper foil shielding layer, the number of active layers is increased by two layers, the cost is increased, but the resistance is low, and the ground layer can be directly designed. c) Silver foil shielding layer, the cost is too high.