PCB Tech - Fourteen important features of high-reliability PCB

Fourteen important features of high-reliability PCB
1. 25 micron hole wall copper thickness

benefit
Enhance reliability, including improving the expansion resistance of the z-axis.
The risk of not doing so
Blow holes or degassing, electrical connectivity problems during assembly (inner layer separation, hole wall fracture), or failure under load conditions in actual use. IPCClass2 (the standard adopted by most factories) requires 20% less copper plating.
2. No welding repair or open circuit repair
benefit

The perfect circuit can ensure reliability and safety, no maintenance, no risk.

The risk of not doing so
If repaired improperly, the circuit board will be broken. Even if the repair is ‘proper’, there is a risk of failure under load conditions (vibration, etc.), which may cause failure in actual use.
3. Exceeding the cleanliness requirements of IPC specifications
benefit
Improving PCB cleanliness can increase reliability.
The risk of not doing so
Residues and solder accumulation on the circuit board bring risks to the solder mask. Ionic residues can cause corrosion and contamination risks on the soldering surface, which may lead to reliability problems (bad solder joints/electrical failures) and ultimately increase the occurrence of actual failures. Probability.

4. Strictly control the service life of each surface treatment
benefit
Solderability, reliability, and reduce the risk of moisture intrusion.

The risk of not doing so
Due to the metallographic changes in the surface treatment of old circuit boards, soldering problems may occur, and moisture intrusion may cause problems such as delamination, separation (open circuit) of the inner layer and the hole wall during the assembly process and/or actual use. .

5. Use internationally well-known substrates-do not use "local" or unknown brands

benefit
Improve reliability and known performance

The risk of not doing so
Poor mechanical performance means that the circuit board cannot perform the expected performance under assembly conditions. For example, high expansion performance will cause delamination, disconnection and warpage problems. Weakened electrical characteristics can lead to poor impedance performance.

6. The tolerance of the copper clad laminate meets the requirements of IPC4101ClassB/L
benefit
Strictly controlling the thickness of the dielectric layer can reduce the deviation of the expected electrical performance.

The risk of not doing so
The electrical performance may not meet the specified requirements, and the output/performance of the same batch of components will be quite different.

7. Define solder mask materials to ensure compliance with IPC-SM-840ClassT requirements

benefit
NCAB Group recognizes "excellent" inks, realizes ink safety, and ensures that solder mask inks meet UL standards.

The risk of not doing so
Inferior inks can cause adhesion, flux resistance, and hardness problems. All these problems will cause the solder mask to separate from the circuit board and eventually lead to corrosion of the copper circuit. Poor insulation properties can cause short circuits due to accidental electrical continuity/arc.

8. Defining the tolerances of shapes, holes and other mechanical features

benefit
Strict control of tolerances can improve the dimensional quality of products-improve fit, shape and function.

The risk of not doing so
Problems in the assembly process, such as alignment/fitting (only when the assembly is completed will the press-fit needle problem be discovered). In addition, due to the increased size deviation, there will be problems when installing the base.

9. NCAB specifies the thickness of the solder mask, although IPC does not have relevant regulations

benefit
Improve the electrical insulation properties, reduce the risk of peeling or loss of adhesion, and strengthen the ability to resist mechanical impact-no matter where the mechanical impact occurs!

The risk of not doing so
Thin solder mask can cause adhesion, flux resistance and hardness problems. All these problems will cause the solder mask to separate from the circuit board and eventually lead to corrosion of the copper circuit. Poor insulation properties due to the thin solder mask can cause short circuits due to accidental conduction/arc.

10. Appearance requirements and repair requirements are defined, although IPC does not define

benefit
Careful care and carefulness in the manufacturing process create safety.

The risk of not doing so
Various scratches, minor injuries, repairs and repairs-the circuit board works but doesn't look good. In addition to the problems that can be seen on the surface, what are the invisible risks, the impact on assembly, and the risks in actual use?