14 Important Features of the High Reliability PCB

Whether it is in the manufacturing assembly process or in actual use, PCB should have reliable performance, which is critical. In addition to the relevant costs, the assembly process defects may be brought into the final product by PCB, in the actual use of the process may occur failure, resulting in claims. Therefore, from this point of view, it can be said without saying that the cost of a piece of high-quality PCB is negligible. In all segments of the market, especially in the production of key applications in the market, the consequences of such failure will be disastrous. 

When comparing PCB prices, these aspects should be kept in mind. Although the initial cost of reliable, guaranteed, and long-life products is high, it is still good value in the long run. Here's a look at 14 of the most important feature of highly reliable PCB boards:

1. 25 um copper thickness of hole wall

Benefits:

Enhanced reliability, including improved expansion resistance ability of the Z-axis.

The risk of not doing it:

The problem of electrical connectivity in hole blowing or degassing, assembly (internal separation, hole wall fracture), or failure may occur in actual use under load conditions. IPCClass2 (the standard adopted by most factories) requires less than 20% copper plating. 

2. No welding repair or open circuit repair

Benefits:

Perfectcircuitry ensures reliability and safety, no maintenance, no risk

The risk of not doing it

If repaired improperly, the circuit board will be broken. Even if repaired properly, there will be a risk of failure in the load conditions (vibration,etc.), which may lead to failure in actual use.

3. Beyond the IPC specification cleanliness requirements

Benefit

ImprovePCB cleanliness can improve reliability.

The risk of not doing it

The residue and solder accumulation on the board will bring risks to the SM layer, and the ion residue will lead to the corrosion and pollution risk of the welding surface, which may lead to the reliability problem (bad solder joint /electrical fault), and finally increase the probability of the actual fault. 

4. Strictly control the service life of each surface finish.

Benefit

Solderability, reliability, and reduce the risk of tidal intrusion

The risk of not doing it

Because of the metallographic change of the surface finish of the old board, the solderability may occur, and the moisture intrusion may lead to delamination, inner layer, and hole wall separation (circuit breaker) in the assembly process and / or actual use. 

5. The use of internationally renowned substrate - does not use the "local" or unknown brand

Benefit

Improving reliability and known performance

The risk of not doing it

Poor mechanical performance means that the board can not perform the desired performance under assembly conditions. For example, higher expansion performance can lead to delamination, open circuit, and warpage problems. The weakening of electrical characteristics leads to poor impedance performance. 

6. Copper clad plate tolerance meetsIPC4101ClassB/L requirements

Benefit

Strictly controlling the thickness of the dielectric layer can reduce the expected deviation of electrical performance.

The risk of not doing it

The electrical performance may not meet the specified requirements, and the output and performance of the same components will vary greatly. 

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7. Define the solder material to meet the requirements of the IPC-SM-840ClassT

Benefit

"Excellent" ink, to achieve the safety of ink, to ensure that the solder resists ink meets the UL standard.

The risk of not doing it

Poor quality ink can cause adhesion, flux resistance, and hardness. All of these problems lead to the separation of the solder layer from the circuit board and eventually lead to copper circuit corrosion. Poor insulation performance can cause a short circuit by the unexpected conduction/arc. 

8. Define tolerances of the profile, hole, and other mechanical features

Benefit

Stricttolerance control can improve the dimensional quality of products - improvement of fit, profile, and function

The risk of not doing it

Assembly problems, such as alignment/fit (only when the assembly is finished will be found with pressure matching pins). In addition, due to the size deviation increases, there will be problems with the base. 

9. The thickness of the solder mask requirements, although IPC has no relevant provisions

Benefit

Improve the electrical insulation characteristics, reduce the risk of spalling or loss of adhesion, and strengthen the ability to fight the mechanical impact -regardless of where the mechanical impact occurs!

The risk of not doing it

Solderthin layer can lead to adhesion, flux resistance, and hardness problems. All of these problems lead to the separation of the solder layer from the circuit board and eventually lead to copper circuit corrosion. Because of the thin layer, the insulation property is not good, and the short circuit can be caused by the unexpected conduction/arc. 

10. Define the appearance and repair requirements, although IPC is not defined

Benefit

Care and carefully create safety in the manufacturing process.

The risk of not doing it

A variety of scratches, small damage, repair - circuit board can be used, but not good-looking. 

11. The hole depth requirement

Benefit

Highquality plug hole will reduce the risk of failure in the assembly process.

The risk of not doing it

Chemicalresidue in the process of ENIG remains in the plug-failure hole, resulting in solderability problems. And the hole may also be in possession of solder ball,assembly or actual use, solder may splash out, causing a short circuit. 

12. Specify the brand and model of peelable blue mask

Benefit

The designation of a Peelable blue mask can avoid the use of "local" or cheap brands.

The risk of not doing it

Inferior cheap brands can be foamed, melted, broken, or solidified like concrete in the process of the assembly so that the Peelable blue mask can not peel off / not work. 

13. Perform specific approval and single order procedures for each purchase order

Benefit

The execution of the program ensures that all specifications have been confirmed.

The risk of not doing it

If the product specifications are not carefully recognized, the resulting deviation may be found at the end of the assembly or final product, and then it is too late. 

14. Do not accept scrap board

Benefit

Nonlocal assembly can help customers improve efficiency.

The risk of not doing it

Special assembly procedures are required for defective panels. It is possible to assemble the known broken plate and waste parts and time if it is not clearly indicated the scrap board (x-out) or is not isolated from the cover plate.