Zhanjiang flexible CIRCUIT board FPC material expansion and shrinkage control methods

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: FPC design products are distributed symmetrically in the whole layout as much as possible. The minimum interval between each two P-CS products should be more than 2 MM.

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

4. Process design side: THE FPC 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 when 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.

Two, material storage

FPC believes in the importance of material storage. It should be stored strictly in accordance with the conditions provided by the material supplier.

Three, manufacturing

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

2. Electroplating: FPC 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: FPC traditional press to rise and shrink than the fast press, the traditional press is constant temperature curing, fast press is hot curing, so the change of the control glue of the transmission press to stabilize this, of course, the lamination of the plate is also a very important part.

4 baking: FPC for fast pressure products, baking is often important part of the 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 of FPC, try to keep the stability of temperature and humidity in all stations. Special attention should be paid to the storage conditions of products for transfer between stations, especially those for external delivery.

4. Packaging

Of course, the completion of FPC products is not to say that 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 true empty packaging, and guide customers how to preserve.

Therefore, to ensure the stable quality of FPC products, specific requirements must be strictly followed from material preservation, process control, packaging to customer use.