High Reliability PCB 14 Important Characteristics

- Jul 26, 2018-

It is essential that the PCB have reliable performance both in the manufacturing assembly process and in actual use.In addition to the related costs, defects in the assembly process may be brought into the final product by PCB, and there may be faults during actual use, resulting in claims.Therefore, from this point of view, it is safe to say that the cost of a high-quality PCB is negligible.
In all segments of the market, especially those that produce critical applications, the consequences of such failures are unthinkable.
These aspects should be kept in mind when comparing PCB prices.While the initial costs of reliable, guaranteed and long-lasting products are high, they are worth it in the long run.
The 14 most important features of high reliability circuit boards
1. Copper thickness of hole wall of 25 microns
benefits
Enhanced reliability, including improved z-axis expansion resistance.
The risk of not doing so
Problems of electrical connectivity in the process of blowing or degassing, or assembly (inner layer separation, hole wall fracture), or possible failure under load conditions during actual use.IPCClass2, the standard used in most factories, requires 20% less copper plating.
2. No welding repair or repair of broken line
benefits
Perfect circuit ensures reliability and safety, no maintenance, no risk
The risk of not doing so
If not repaired properly, the circuit board will be cut off.Even if the repair is "proper", there is a risk of failure under load conditions (vibration, etc.), which may lead to failure in practical use.
3. Exceeding the cleanliness requirement of IPC specification
benefits
Improving PCB cleanliness improves reliability.
The risk of not doing so
The accumulation of residues and solder on the circuit board will bring risks to the anti-welding layer, and the ion residues will lead to the risk of corrosion and pollution on the welding surface, which may lead to reliability problems (bad solder joints/electrical failures) and ultimately increase the probability of actual failures.
4. Strictly control the service life of each surface treatment
benefits
Soldering, reliability, and reduced risk of moisture intrusion
The risk of not doing so
Soldering problems may occur due to changes in the metal phase of the surface treatment of the old circuit board, while moisture intrusion may lead to problems such as lamination, separation of inner layer and hole wall (breaking off) during assembly and/or actual use.
5. Use internationally renowned materials -- no "local" or unknown brands
benefits
Improved 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, higher expansion performance will lead to stratification, circuit breaking and warping problems.Weak electrical characteristics can lead to poor impedance performance.
6. Copper clad plate tolerance meets the requirements of IPC4101ClassB/L
benefits
Strictly controlling the thickness of dielectric layer can reduce the deviation of electrical performance expectation.
The risk of not doing so
The electrical performance may not meet the specified requirements, and the same batch of components may differ greatly in output/performance.
7. Define welding resistance materials to ensure that they meet the requirements of ipc-sm-840classt
benefits
NCAB group recognizes "excellent" inks to achieve ink safety and ensure that soldering layer inks meet UL standards.
The risk of not doing so
Poor quality ink can lead to adhesion, flux resistance and hardness problems.All of these problems will result in the soldering layer disengaging from the circuit board and eventually lead to corrosion of the copper circuit.Poor insulation can be short-circuited by unexpected electrical connectivity/arc.
8. Define tolerance of appearance, hole and other mechanical features
benefits
Strict tolerance control can improve the size and quality of products - improve fit, shape and function
The risk of not doing so
Problems during assembly, such as alignment/fit (problems with the press-fit needle are found only when the assembly is complete).In addition, as the size deviation increases, loading the base will also be a problem.
9. NCAB specifies the thickness of the resistance layer, although IPC does not specify such thickness
benefits
Improving electrical insulation, reducing the risk of peeling or losing adhesion, and strengthening the ability to withstand mechanical walls-wherever mechanical wallops occur!
The risk of not doing so
The thin resistance layer can lead to adhesion, flux resistance and hardness problems.All of these problems will result in the soldering layer disengaging from the circuit board and eventually lead to corrosion of the copper circuit.Poor insulation due to thin resistance layer and short circuit due to accidental lead/arc.
10. The appearance requirements and repair requirements are defined, although IPC is not defined
benefits
It is safe to protect and cast carefully in the manufacturing process.
The risk of not doing so
A variety of abrasions, minor injuries, repairs and repairs - the circuit board can be used but not good-looking.In addition to the apparent problems, what are the hidden risks, the impact on assembly, and the risks in actual use?
11. Requirements for hole depth
benefits
High quality plug holes reduce the risk of failure during assembly.
The risk of not doing so
The chemical residues in the process of gold deposition can be residual in the hole with unfilled hole, thus causing solderability and other problems.In addition, the hole may contain tin beads, which may splash out during assembly or actual use, causing short circuit.
12. PetersSD2955 specifies the brand and model of peeling blue glue
benefits
The designation of bluestone can avoid the use of "local" or cheap brands.
The risk of not doing so
Poor quality or cheap solderable glue may bubble, melt, break, or solidify like concrete during the assembly process, making the solderable glue unable to be removed/useless.
13. NCAB performs specific approval and ordering procedures for each purchase order
benefits
The implementation of this procedure ensures that all specifications have been confirmed.
The risk of not doing so
If the product specification is not carefully confirmed, the resulting deviation may not be detected until the assembly or final product, which is too late.
14. No shell plates with scrapped units are acceptable
benefits
Not using partial assembly can help customers improve efficiency.
The risk of not doing so
Defective panels require special assembly procedures, and it is possible to assemble the known broken plate without clearly marking the scrap unit plate (x-out), or without isolating it from the casing, thus wasting parts and time.