PCB News - Several important features of PCB board to improve reliability

Several important features of PCB board to improve reliability

The 14 most important characteristics of high-reliability circuit boards

1. 25 micron hole wall copper thickness

Benefits: Enhance reliability, including improving the expansion resistance of the z-axis.

The risk of not doing so

Blow holes or degassing, electrical connectivity problems during assembly (inner layer separation, hole wall breakage), or failure under load conditions in actual use.

IPCClass2 (the standard adopted by most PCB factories) requires 20% less copper plating.

2. No welding repair or open circuit repair

Benefits: perfect circuit can ensure reliability and safety, no maintenance, no risk

The risk of not doing so

If repaired improperly, the circuit board will be broken. Even if the repair is ‘proper’, there is a risk of failure under load conditions (vibration, etc.), which may

Failure in actual use.

3. Exceeding the cleanliness requirements of IPC specifications

Benefit: Improving PCB cleanliness can increase reliability.

The risk of not doing so

Residues and solder accumulation on the circuit board bring risks to the solder mask. Ionic residues can cause corrosion and contamination risks on the soldering surface, which may lead to reliability problems)

(Bad solder joints/electrical failure), and ultimately increase the probability of actual failure.

4. Strictly control the service life of each surface treatment

Benefits: solderability, reliability, and reduce the risk of moisture intrusion

The risk of not doing so

Because the surface treatment of old circuit boards will undergo metallographic changes, soldering problems may occur, and moisture intrusion may cause the assembly process and/or actual use

Problems such as delamination, separation of the inner layer and the hole wall (open circuit) occur.

5. Use internationally well-known substrates-do not use "local" or unknown brands

Benefit: 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, high expansion performance will cause delamination, disconnection and warpage problems. Electrical characteristics

Weakness can lead to poor impedance performance.

6. The tolerance of the copper clad laminate meets the requirements of IPC4101ClassB/L

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

The risk of not doing so

The electrical performance may not meet the specified requirements, and the output/performance of the same batch of components will be quite different.

7. Define solder mask materials to ensure compliance with IPC-SM-840ClassT requirements

Benefits: NCAB Group recognizes "excellent" inks, realizes ink safety, and ensures that solder mask inks meet UL standards.

The risk of not doing so

Inferior inks can cause adhesion, flux resistance, and hardness problems. All these problems will cause the solder mask to separate from the circuit board and eventually lead to corrosion of the copper circuit. insulation

Poor characteristics can cause a short circuit due to unexpected electrical continuity/arc.

8. Defining the tolerances of shapes, holes and other mechanical features

Benefits: Strict control of tolerances can improve the dimensional quality of products-improve fit, shape and function

The risk of not doing so

Problems in the assembly process, such as alignment/fitting (only when the assembly is completed will the press-fit needle problem be discovered). In addition, due to the increased size deviation, there will be problems when installing the base.

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