PCB boards often peel off the original size Reasons

(1) Supplier material or process problems

(2) Poor design material selection and copper surface distribution

(3) The storage time is too long, which exceeds the storage time, and the PCB board is damp.

(4) Improper packaging or storage, damp countermeasures: choose packaging and use constant temperature and humidity equipment for storage. Excellent performance in PCB factory reliability test, e.g. thermal stress test in PCB reliability test. 5 times or more non-layering is the standard for responsible providers and verified at the sample stage. A typical manufacturer can only request it twice per production cycle, and only check it once every few months. IR testing in simulated batches also prevents more spills of defective products, which are a prerequisite for quality PCB factories. In addition, the Tg of PCB board should be selected above 145C to ensure safety.

Reliability test equipment: constant temperature and humidity box, stress shield type thermal shock test box, PCB reliability test equipment

Poor demonstrability of PCB board

Reason: Long storage time, will lead to water absorption, contamination and map oxidation, abnormal black nickel, flux resistance SCUM(shadow) and flux resistance PAD.

Solution: When purchasing, pay close attention to the PCB factory's quality control plan and maintenance standards. For example, it is necessary to check the presence of black nickel, the presence of chemical gold in the PCB manufacturing plant, the stability of the concentration of chemical gold wire, the adequacy of the frequency of analysis, and the availability of regular gold stripping tests and phosphorus content tests. Whether the test and internal weldability test run well, etc.

What are the ways to increase PCB flexibility?

PCB circuit boards are often used in the manufacturing process of flexible materials, in the hope that printed circuit boards can meet all the needs of bending, bending and some special circuit applications. However, flexible materials alone do not guarantee the reliability of circuit function when completely bent or bent, especially in dynamic applications. Many methods can be used to increase the flexibility of the printed circuit board to ensure the reliability of the board molding or repeated bending. So, what are the ways to increase PCB flexibility?

What are the principles of PCB special component layout?

PCB design requirements by dry, often need to some special components on the board layout, such as large components, components, heating components, transformers, | C, etc. One-day layout

Bad, PCB circuit board will appear serious quality problems, resulting in the whole board scrap. So, what are the principles of PCB special component layout?

1. For some components or wires with higher potential difference, the distance between them should be increased to avoid accidental short circuit due to component discharge. High voltage components should be placed out of reach of hands as far as possible.

2, should shorten the connection between high-frequency components as far as possible, try to reduce their distribution parameters and mutual electromagnetic interference, easy to interfere with the components should be far away.

3, the weight of more than 15G components, can be fixed by support, and then brilliant connection. For those heavy and hot components, should not be placed on the board, should be placed in the main box

On the bottom plate, the aim should take full account of the heat dissipation problem. For dry heat-sensitive components, keep away from heat-producing components as far as possible.

4. For the layout of adjustable components such as potentiometer, adjustable conductor coil, variable capacitor and micro switch, the structural requirements of the whole board should be considered; Frequently used switching components,

Where the structure permits, it should be placed within easy reach of the hand.

In short, components from layout to balance, density, can not be top-heavy. The success of a product, one should pay attention to the internal quality. Two to take into account the overall beauty, both are compared

The perfect board is a successful PCB circuit board product.