King Sun PCB

The production process of a flexible printed circuit board is basically similar rigid PCB.For some operations, the flexibility of the laminates requires different devices and completely different processing methods.Most flexible PCB uses a negative method.However, there are some difficulties in the machining of flexible laminated plates and in the process of coaxial processing.One of the main problems is the processing of the base material. Flexible materials are rolls of different width, so during the etching, the flexible laminates need to be used as a rigid bracket.

In the process of production, the processing and cleaning of the flexible printed circuit is more important than the rigid plate.Incorrect cleaning or violation of regulations may lead to failure in product manufacturing. This is due to the sensitivity of materials used in flexible printed circuit. In the manufacturing process, flexible printed circuit plays an important role.The substrate is affected by mechanical pressure such as wax drying, lamination and electroplating. Copper foil is also susceptible to percussion and dent, and the extension ensures maximum flexibility. Mechanical damage or hardening of copper foil will reduce the flexibility life of the circuit.

During the manufacturing period, a typical flexible single side circuit needs to be cleaned at least three times. However, multiple substrates need to be cleaned 3-6 times because of its complexity.In contrast, rigid multilayer printed circuit boards may require the same number of cleaning times, but the cleaning procedure is different, so we need to be more careful when cleaning flexible materials.Even by light pressure in the cleaning process, the spatial stability of flexible materials will also be affected, and will cause the panel elongated in the Z or Y direction, depending on the bias pressure. The chemical cleaning of the flexible printed circuit board should pay attention to the environmental protection. The cleaning process includes alkaline bath, thorough rinsing, micro etching, and final cleaning.The damage of thin film often occurs in the process of panel mounting, when it is stirred in the pool, the rack is removed from the pool, or the surface tension is not destroyed when it is not on the shelf.

Punching holes are generally used in the holes in the flexible plate, which leads to the increase of the processing cost. Drilling is also possible, but this requires special adjustment of drilling parameters, so as to obtain the hole wall without smear. After drilling, the drilled dirt is removed in a water cleaner with ultrasonic stirring.

Mass production of flexible panels is cheaper than rigid printed circuit board.This is because flexible laminates enable manufacturers to produce circuits on a continuous basis. This process starts directly from laminates, and directly generates finished products.In order to fabricate printed circuit boards and etch a continuous processing schematic diagram of flexible printed circuit boards, all production processes are completed in a series of sequential placement machines. Screen printing may not be part of the continuous transmission process, which causes an interruption of the online process.

Usually, because of the heat resistance of the substrate, the welding in the flexible printed circuit is more important.Manual welding requires sufficient experience, so if possible, wave soldering should be used. In welding flexible printed circuit, the following matters should be paid attention to:

• Because polyimide is hygroscopic, the circuit must be baked before welding (continuous 1h in 250 F)
• The pads are placed on large conductor areas, such as ground layer, power layer, or radiator, which should be reduce heat emission and makes the welding easier.
• When a hand welding pin is carried out in a dense area, it is necessary to avoid continuous welding of the adjacent pins and move the welding back and forth in order to avoid local overheating.