FPC(Flexible Printed Circuit) means Flexible Printed Circuit board.This kind of circuit board has the advantages of high wiring density, light weight and thin thickness and is widely used in mobile phones, laptops, PDA, digital camera, LCM and many other products.
In recent years, PCB manufacturing technology has developed rapidly, and the industry has put forward higher requirements for FPC.The stability and delicacy of size also lead to the rise of the cost of FPC. How to control the contradiction between the two, in the production process of FPC material expansion and contraction control has become the main breakthrough.
Below we on how to control, control of the main points for you to make a brief explanation.
1. Circuit: since FPC will expand due to temperature and pressure in ACF compression, expansion rate of compression finger should be considered in the initial design of the circuit to conduct pre-compensation treatment;
2. Layout: the designed products should be distributed evenly and symmetrically throughout the layout as far as possible. The minimum interval between each two PCS should be kept above 2MM.
3. Material selection: the adhesive covering the film shall not be thinner than the thickness of the copper foil, so as to avoid deformation caused by insufficient filling of the adhesive when pressing. The thickness of the adhesive and whether it is evenly distributed, which is the main culprits for the rise and contraction of FPC materials.
4. Process design: covering film shall cover all parts of copper foil as far as possible, and it is not recommended to paste covering film on strips to avoid uneven force during suppression. PI reinforcing and laminating surface glue above 5MIL shall not be too large.
Ii. Material storage
I believe in the importance of material storage, I don’t need to say more, need to be in strict accordance with the conditions provided by the supplier of materials storage, refrigeration, everything should not be careless.
1. Drilling: it is better to add baking before drilling to reduce the expansion and shrinkage of the substrate during subsequent processing due to the high content of water in the substrate.
2. In electroplating, short side splint should be used to reduce the water stress caused by swing and cause deformation. When electroplating, swing can be reduced to minimize the swing range.Electroplating, live under the groove, to avoid sudden high current impact on the plate, so as not to cause bad impact on the plate electroplating.
3. Pressing: the traditional press is smaller than fast press, the traditional press is constant temperature curing, fast press is thermal curing, so the traditional press control glue change to stabilize this, of course, the lamination of the row is also a very important part.
4. Baking: for fast pressure products, baking is a very important part, the baking condition must be reached to make the glue completely cured, or in the subsequent production or use of endless problems. Generally, the baking temperature curve rises gradually to the temperature when the glue completely melts, and then continues to this temperature until the glue completely solidifies, and then gradually cools down and cools down.
5. In the production process, try to maintain the stability of temperature and humidity in all stations, and transfer between stations, especially those that need to be outsourced, and pay special attention to the storage conditions of products.
Of course, the completion of the product is not to say that everything is fine, we need to ensure that customers in the subsequent use of no problems, in the packaging, it is best to bake, the product in the manufacturing process by the absorption of water drying, vacuum packaging, and guide customers how to save.
Therefore, to ensure the stable quality of this kind of products, we must strictly follow the specific requirements from material preservation, control of each process, packaging and customer use.
Post time: Aug-27-2019