FPC (Flexible Printed Circuit) refers to soft printed circuit board, also known as flexible printed circuit board, flexible printed circuit board or flexible board. This circuit board has the advantages of high wiring density, light weight and thin thICkness. Widely used in mobile phones, laptop computers, PDA, digital CAMera, LCM and many other products. In recent years, with the rapid development of PCB manufacturing process, 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 to control the growth and shrinkage of FPC materials in the production process. Here we give you a brief explanation on how to control and control the main points.
1. Line: Because FPC will expand due to temperature and pressure during ACF crimping, the expansion rate of crimping finger should be considered in the initial design of the line, and pre-compensation processing should be carried out;
2. Typesetting: Design products should be evenly and symmetrically distributed throughout the typesetting as far as possible. The minimum interval between each two PCB product should be kept at least 2MM, and the copper-free part and the part with dense pores should be staggered as far as possible.
3. Material selection: the glue of the 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 when pressing, the thickness of the glue and whether the distribution is uniform, is the main culprit of the shrinkage of FPC board material.
4. In terms of process design: covering film as far as possible to cover all copper foil parts, it is not recommended to stick covering film, to avoid uneven force when pressing, more than 5MIL PI reinforcement bonding surface adhesive should not be too large, if it cannot be avoided, it is necessary to press and bake the covering film before PI reinforcement bonding.
Two, material storage
I do not need to say more about the importance of material storage. It is necessary to store in strict accordance with the conditions provided by the material supplier. What should be refrigerated should be refrigerated.
1. Drilling: it is best to add baking before drilling to reduce the expansion and contraction of the substrate during subsequent processing due to the high moisture content in the substrate.
2. Electroplating: should be made with short side splint, can reduce the swing caused by water stress deformation, electroplating swing can reduce as far as possible to reduce the swing amplitude, the number of splint also has a certain relationship, the number of asymmetric splint, available other side material to assist; When electroplating, the tank is charged to avoid sudden high current impact on the plate, so as not to cause adverse effects on plate plating.
3. Pressing: the traditional pressing machine is SMAller than the fast press, the traditional press is constant temperature curing, the fast press is hot curing, so the change of the traditional press control glue to stabilize this, of course, the laminating plate is also a very important part.
4 Baking: for fast pressure products, baking is a very important part, baking conditions must be achieved to make the glue completely cured, otherwise in the follow-up production or use of infinite trouble; Generally, the baking temperature curve is gradually raised to the temperature of complete melting of the glue, and then continued at this temperature until the glue is completely cured, and then gradually cooLED down.
5. In 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 products during the transfer between stations, especially those that need to be made out.
Of course, everything is not all right when the product is completed. It is necessary to ensure that the customer does not have any problems in the subsequent use. In terms of packaging, it is best to bake the product first, dry the moisture absorbed by the substrate in the manufacturing process, and then use vacuum packaging, and guide the customer how to preserve.
Therefore, to ensure the stability of the quality of this kind of products from the material preservation to the process control to packaging to customers before use must be strictly in accordance with the specific requirements to execute.
In the coming years, smaller, more complex, and more expensive to assemble flexible circuits will require more novel methods of assembly and the addition of hybrid flexible circuits. The challenge for the flexible circuit industry is to take advantage of its technological advantages and stay abreast of computers, telecommunications, consumer demand, and dynamic markets. Shiji Core PCB production and processing service department has a group of high-level technical backbone and front-line operators, to ensure the quality of products to provide a reliable guarantee (according to IPC-A-610CCLASSⅡ and company standards), the production of products a delivery pass rate reached more than 99%.