What are the control methods of FPC material shrinkage of flexible circuit board

Flexible Printed Circuit (FPC) refers to the Flexible Printed Circuit board (FPC), also known as the Flexible Printed Circuit board, Flexible Printed Circuit board, or Flexible Printed Circuit board. The circuit board has the advantages of high wiring density, light weight and thin thickness. Widely used in mobile phones. Laptop. 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. Precision PITCH is the main breakthrough direction of FPC in the future. The stability and delicacy of the size also lead to the rise of the cost of FPC. How to control the contradiction between the two is the main breakthrough of FPC material expansion and contraction control in the production process. Here's how to control it. The main points of control are briefly explained to you.

First, design

1. Circuit: FPC will expand due to temperature and pressure during ACF crimping, so the expansion rate of crimping fingers should be considered in the initial design of the circuit and pre-compensation treatment should be carried out;

2. Layout: The design products are distributed symmetrically throughout the layout as much as possible, and the minimum interval between each two P-CS products should be more than 2 MM. The copper-free part and the heavily perforated part should be staggered as far as possible, which are two important aspects affected by material expansion and contraction in subsequent manufacturing process.

3. Material selection: the glue covering the film can not be too thin than the thickness of the copper foil, so as to avoid the deformation of the product caused by the insufficient filling of the glue when pressing. The thickness of the glue and whether it is evenly distributed are the culprit of the expansion and contraction of THE FPC material.

4. Process design side: the covering film should cover all copper foil parts as far as possible, and it is not recommended to stick the covering film to avoid uneven force during pressing. The PI reinforcing bonding surface glue on 5MIL should not be too large, if it cannot be avoided, the covering film should be pressed and baked before PI reinforcing bonding pressing.

Two, material storage

I believe that the importance of material storage need not say more, it is necessary to store in strict accordance with the conditions provided by the material supplier, the cold storage of the cold storage, not careless.

Three, manufacturing

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

2. Electroplating: it should be made of short side plywood, which can reduce the deformation caused by the water stress caused by the swing. When electroplating, the swing kinetic energy reduces the impact on the plate, so as not to cause adverse effects on the plate electroplating.

3. Pressing: the traditional press is up and down more than the fast press. The traditional press is constant temperature curing, and the fast press is hot curing, so the change of the control glue of the transmission press should be stable, of course, the laminating plate is also a very important part.

4. Baking: for fast pressure products, baking is not often important part, baking conditions must be reached to make the glue completely solidified, otherwise in the subsequent production or use after infinite; The baking temperature curve is first gradually rising to the temperature at which the glue is completely melted, and then continuing at this temperature until the glue is completely solidified, and then gradually decreasing the temperature and cooling.

5. During the production process, try to maintain the stability of temperature and humidity in all stations. Special attention should be paid to the storage conditions of the products when transferring between stations, especially when the products need to be sent out.

4. Packaging

Of course, the completion of the product is not to say all is well, it is necessary to ensure that customers do not have any problems in the subsequent use, in terms of packaging, it is best to bake first, drying the moisture absorbed by the base material in the manufacturing process, and then using the true empty packaging, and guide customers how to preserve.

Therefore, to ensure the stability of the quality of such products, it is necessary to strictly comply with specific requirements from material preservation, process control, packaging and customer use.