Fourteen Important Features of High Reliability PCB (1)

At first glance, PCBs appear to be similar on the surface, regardless of their intrinsic quality. It is through the surface that we see the differences that are critical to the durability and functionality of the PCB throughout its life.

Whether it is in the manufacturing assembly process or in actual use, it is critical that PCBs have reliable performance. In addition to the associated costs, defects in the assembly process may be brought into the final product by the PCB, which may fail during actual use, leading to claims. Therefore, from this point of view, it is no exaggeration to say that the cost of a good quality PCB is negligible. In all market segments, especially those producing products in critical application areas, the consequences of such failures are disastrous.

These aspects should be kept in mind when comparing PCB prices. While reliable, guaranteed, and long-life products have a higher initial cost, they are worthwhile in the long run. Let’s take a look at the 14 most important characteristics of high-reliability circuit boards:

1. The copper thickness of the hole wall of 25 microns
Benefit:
Enhanced reliability, including improved z-axis expansion resistance.

Risks of not doing so:
Hole blowing or degassing, electrical connectivity problems during assembly (separation of inner layers, breakage of hole walls), or possible failure under load conditions in actual use. IPCClass2 (the standard adopted by most factories) specifies 20% less copper plating.

2. No welding repair or open circuit repair
Benefit:
A perfect circuit ensures reliability and safety, no maintenance, and no risk.
Risk of not doing so:
If it is not repaired properly, it will cause the circuit board to open. Even if repaired ‘properly’, there is a risk of failure under load conditions (vibration, etc.) that may fail in actual use.

3. Exceed the cleanliness requirements of IPC specifications
Benefit:
Improved PCB cleanliness improves reliability.

The risk of not doing so:
Residues, solder build-up on the board pose a risk to the solder mask, ionic residues can cause corrosion and contamination of the solder surface, which can lead to reliability issues (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 reduced risk of moisture intrusion.

The risk of not doing so:
Solderability problems may occur due to metallographic changes in the surface treatment of older boards, while moisture intrusion may cause delamination, inner layer and hole wall separation (open circuit) problems during assembly and/or actual use.

5. Use internationally renowned substrates – do not use “local” or unknown brands
Benefit:
Improved reliability and known performance.

The risk of not doing so:
Poor mechanical properties mean that the board does not perform as expected under the assembled conditions, for example: higher expansion properties can lead to delamination, open circuit and warpage problems. Impaired electrical properties can result in poor impedance performance.