PCB regardless of the internal quality, the surface is similar. It is through the surface that we see the differences, and these differences are critical to the durability and functionality of the PCB throughout its life.
Whether in the manufacturing assembly process or in actual use, it is crucial that the PCB has reliable performance. In addition to the associated costs, defects in the assembly process may be carried by the PCB into the final product, and failures may occur during actual use, leading to claims. Therefore, from this point of view, it is not unreasonable to say that the cost of a high-quality PCB is negligible.
In all market segments, especially those producing products for critical application areas, the consequences of such failures are unimaginable. These aspects should be kept in mind when comparing PCB prices. Although reliable, guaranteed and long-life products have higher initial costs, they are worth it in the long run.
The 14 most important characteristics of a highly reliable circuit board are as follows:
1. 25 micron hole wall copper thickness
Benefits: Enhanced reliability, including improved Z-axis expansion resistance.
Risks: hole blowing or degassing, electrical connectivity problems during assembly (inner layer separation, hole wall breakage), or the possibility of failure under load conditions in actual use. IPCClass2 (the standard adopted by most factories) requires 20% less copper plating.
2. no welding repair or broken line repair
Benefits: Perfect circuitry ensures reliability and safety, no maintenance, no risk
Risk: If the repair is not proper, it will cause the circuit board to break. Even if the repair is' properly ', there is a risk of failure under load conditions (vibration, etc.), which may cause failure in actual use.
3. Exceed the cleanliness requirements of IPC specifications
Benefits: Increased PCB cleanliness improves reliability.
Risks: Residue and solder buildup on the circuit board poses risks to the solder shield layer, and ionic residue poses risks of corrosion and contamination of the weld surface, which can lead to reliability issues (poor solder joints/electrical failures) and ultimately increase the probability of actual failure.
4. strictly control the service life of each surface treatment
Benefits: Solderability, reliability, and reduced risk of moisture intrusion
Risks: Solderability problems can occur due to metallography changes in the surface treatment of older boards, and moisture intrusion can lead to issues such as delamination, inner layer and hole wall separation (break off) during assembly and/or actual use.
5. Use internationally renowned substrates - do not use "local" or unknown brands
Benefits: Improved reliability and known performance
Risks: Poor mechanical properties mean that the board will not perform as expected under assembly conditions, for example: high expansion properties can lead to delamination, breaking, and warping problems. Weakening of electrical characteristics can lead to poor impedance performance.
6. copper clad plate tolerance in line with IPC4101ClassB/L requirements
Benefits: Strict control of dielectric layer thickness can reduce the deviation of the expected value of electrical performance.
Risks: Electrical performance may not meet the specified requirements, and the output/performance of the same batch of components may vary greatly.
7. Define solder resistance materials to ensure compliance with IPC-SM-840ClassT requirements
Benefits: NCAB Group recognizes "good" inks for ink safety and ensures that solder resistance inks comply with UL standards.
Risks: Poor quality inks can cause problems with adhesion, flux resistance and hardness. All of these problems can cause the solder stop layer to detach from the circuit board and eventually lead to corrosion of the copper circuit. Poor insulation characteristics can cause short circuits due to unexpected electrical connectivity/arcing.
8. Define tolerances for shapes, holes and other mechanical features
Benefits: Strict control of tolerances can improve the dimensional quality of the product - improving fit, shape and function
Risk: Problems during assembly, such as alignment/fit (problems with pressing pins are only discovered when assembly is complete). In addition, due to the increased size deviation, loading the base will also be problematic.
9. NCAB specifies the solder mask thickness, although IPC does not specify it
Benefits: Improved electrical insulation, reduced risk of flaking or loss of adhesion, enhanced resistance to mechanical impact - wherever it occurs!
Risks: A thin solder mask can cause problems with adhesion, flux resistance and hardness. All of these problems can cause the solder stop layer to detach from the circuit board and eventually lead to corrosion of the copper circuit. Poor insulation due to thin solder resistance layer can cause short circuit due to unexpected conduction/arc.
10. defined the appearance requirements and repair requirements, although IPC did not define
Benefits: Careful care and careful casting of safety in the manufacturing process.
Risks: Multiple scrapes, minor damage, repairs and repairs - the board works but is not pretty. In addition to the problems that can be seen on the surface, what are the invisible risks, as well as the impact on assembly, and the risks in actual use?
11. Requirements for the depth of the plug hole
Benefits: High quality jack will reduce the risk of failure during assembly.
Risk: Chemical residue from the gold settling process can remain in holes with inadequate plugs, causing problems such as solderability. Moreover, tin beads may also be hidden in the hole, which may splash out in assembly or actual use, causing a short circuit.
12. PetersSD2955 Specifies the brand and model of peeling blue glue
Benefits: The designation of peelable blue glue avoids the use of "local" or cheap brands.
Risk: Poor quality or cheap peelable glue may bubble, melt, crack, or set like concrete during assembly, making the peelable glue unpeeling/ineffective.
13. NCAB implements specific approval and placing procedures for each purchase order
Benefits: The execution of the procedure ensures that all specifications have been confirmed.
Risk: If product specifications are not carefully confirmed, the resulting deviation may not be discovered until assembly or the final product, when it is too late.
14. do not accept the sleeve plate with scrap unit
Benefits: Not using partial assembly helps customers improve efficiency.
Risk: Defective sheeting requires special assembly procedures, and if the scrap unit board (x-out) is not clearly marked, or it is not isolated from the sheeting, it is possible to assemble the known broken board, wasting parts and time.
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