PCBs are 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.
It is critical that PCBs have reliable performance, both in the manufacturing assembly process and in actual use. 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.
Fourteen important features of high-reliability PCB circuit boards
1. 25 micron hole wall copper thickness
Benefits: Enhanced reliability, including improved z-axis expansion resistance.
Risks: blow holes or outgassing, electrical connectivity issues during assembly (separation of inner layers, breakage of hole walls), or potential 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
Benefits: perfect circuit for reliability and safety, no maintenance, no risk
Risk: If not repaired properly, the circuit board will open circuit. 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.
Risks: Residues, solder buildup on the board pose risks to the solder mask, ionic residues can cause corrosion on the solder surface and risk of contamination which can lead to reliability issues (bad solder joints/electrical failures) and ultimately increase actual failures probability of occurrence.
4. Strictly control the service life of each surface treatment
Benefits: Solderability, reliability, and reduced risk of moisture intrusion
Risks: Solderability issues may occur due to metallographic changes in the surface finish of older boards, while moisture intrusion may lead to delamination, inner layer and hole wall separation (open circuit) during assembly and/or actual use And other issues.
5. Use internationally known substrates – do not use “local” or unknown brands
Benefit: Improved reliability and known performance
Risk: Poor mechanical properties mean that the board will not perform as expected under the assembled conditions, e.g. high expansion can lead to delamination, open circuit and warpage issues. Impaired electrical properties can result in poor impedance performance.
6. The tolerance of CCL meets the requirements of IPC4101ClassB/L
Benefit: Tight control of dielectric layer thickness reduces deviation from expected electrical performance.
Risk: The electrical performance may not meet the specified requirements, and the output/performance of the same batch of components may vary greatly.
7. Define solder mask materials to ensure compliance with IPC-SM-840ClassT requirements
Benefits: NCAB Group recognizes "good" inks for ink safety, ensuring solder mask inks meet UL standards.
Risks: Poor quality inks can cause adhesion, flux resistance and hardness problems. All of these problems can cause the solder mask to detach from the board and eventually lead to corrosion of the copper circuit. Poor insulation properties can cause short circuits due to accidental electrical continuity/arcing.
8. Tolerances defining shapes, holes, and other mechanical features
Benefit: Tight tolerances improve product dimensional quality – improved fit, form and function
Risks: Problems during assembly, such as alignment/mating (problems with press-fit pins are only discovered when assembly is complete). In addition, the mounting into the base can also be problematic due to increased dimensional deviations.
9. NCAB specifies the thickness of the solder mask, although IPC has no relevant regulations
Benefits: Improved electrical insulation properties, reduced risk of peeling or loss of adhesion, increased resistance to mechanical shock – wherever it occurs!
Risk: Thin solder mask can lead to adhesion, flux resistance and hardness problems. All of these problems can cause the solder mask to detach from the board and eventually lead to corrosion of the copper circuit. Poor insulation properties due to thin solder mask, can cause short circuits due to accidental conduction/arcing.
10. Defines appearance requirements and repair requirements, although IPC does not define them
BENEFITS: Safety is created with care and care in the manufacturing process.
Risks: Multiple scratches, minor damages, patching and repairs - circuit boards work but don't look good. In addition to the problems that can be seen on the surface, what are the unseen risks, the impact on assembly, and the risks in actual use?
11. Requirements for the depth of the plug hole
Benefit: High-quality plug holes will reduce the risk of failure during assembly.
Risks: Chemical residues from the gold immersion process can remain in holes that are not fully plugged, causing problems such as solderability. In addition, there may also be tin beads hidden in the holes. During assembly or actual use, the tin beads may splash out and cause a short circuit.
12, PetersSD2955 designated peelable blue glue brand and model
Benefit: Designation of peelable blue glue avoids the use of "local" or cheap brands.
Risk: Poor quality or cheap peelables may foam, melt, crack or set like concrete during assembly, making the peelable/ineffective.
13. NCAB implements specific approval and ordering procedures for each purchase order
Benefit: The execution of this procedure ensures that all specifications have been confirmed.
Risk: If product specifications are not carefully confirmed, the resulting deviations may not be discovered until assembly or final product, when it is too late.
14. Sets with scrapped units are not accepted
Benefit: Not using partial assembly can help customers improve efficiency.
Risk: Defective kits require special assembly procedures, and it is possible to assemble a known bad board if it is not clear to mark the end-of-life unit board (x-out), or to isolate it from the kit , thereby wasting parts and time.
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