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What problems should be paid attention to in the production process of FPC flexible circuit board?

Industry News|2022-02-20| admin

  In the production process, the processing and cleaning of flexible circuit boards are more important than the processing of PCB boards.

  Improper cleaning or operations that violate the regulations may lead to subsequent failures in product production. This is due to the sensitivity of the materials used in flexible printed circuits. Flexible printed circuits play an important role in the production process.

  The substrate is subject to mechanical stress such as wax baking, lamination and electroplating, and the copper foil is also susceptible to knocks and dents, while the extension ensures maximum flexibility. Mechanical damage or work hardening of the copper foil will reduce the flexible life of the circuit.

  A typical flexible single-sided circuit requires at least three cleanings during fabrication, however, multi-substrates require 3-6 cleanings due to their complexity.

  In comparison, rigid multilayer printed circuit boards may require the same number of cleaning cycles, but the cleaning procedures are different and more care needs to be taken when cleaning flexible materials.

  Even with very light pressure during the cleaning process, the dimensional stability of the flexible material can be affected and can cause the panel to elongate in the z or y direction, depending on the bias of the pressure.

  The chemical cleaning of flexible printed circuit boards should pay attention to environmental protection. The cleaning process includes an alkaline dye bath, a thorough rinse, micro-etching and a final cleaning. Damage to the film material often occurs during the panel racking process, during agitation in the tank, when racks are removed from the tank or when racks are not erected, and surface tension damage during tank cleaning.

  The holes in the flexible board are generally punched, which leads to an increase in processing costs. Drilling is also possible, but this requires special adjustment of the drilling parameters to obtain a smear-free hole wall. After drilling, remove the drilling dirt in a water cleaner with ultrasonic agitation.

  Mass production of flexible boards has proven to be cheaper than rigid printed circuit boards. This is because flexible laminates allow manufacturers to produce circuits on a continuous basis, a process that starts with a laminate roll and leads directly to finished boards.

  In order to make a printed circuit board and etch a schematic diagram of a continuous processing of flexible printed circuit boards, all production processes are completed in a series of sequentially placed machines. Screen printing may not have been part of this sequential transfer process, causing the in-line process to abort.

  Generally, soldering in flexible printed circuits is more important due to the limited heat resistance of the substrate. Technical soldering requires sufficient experience, so if possible, wave soldering should be used.

  When soldering a flexible circuit board circuit, you should pay attention to the following matters:

  1. Since polyimide is hygroscopic, the circuit must be baked (250°F for 1h) before soldering.

  2. The pad is placed on a large conductor area, such as a ground layer, a power layer or a heat sink, and the heat dissipation area should be reduced, which limits the heat generation and makes soldering easier.

  3. When manually welding pins in a densely populated place, try not to connect the pins near the welding

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