Introduction To The Important Features Of High Reliability PCB

At first glance, PCB’s 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 a PCB throughout its life. It is essential that PCB has reliable performance both in the manufacturing assembly process and in practical use. In addition to the associated costs, defects in the assembly process may be brought into the final product from the PCB and may malfunction during actual use, resulting in claims. So from this point of view, it is safe to say that the cost of a good PCB is negligible.

In all market segments, especially those producing products in critical application areas, the consequences of such failures are unimaginable. Keep these aspects in mind when comparing PCB prices. Although reliable, guaranteed and long-life products have higher initial costs, they are worth the money in the long run. Fourteen of the most important features of highly reliable circuit boards

1. Copper thickness of hole wall of 25 microns

Benefits: Enhanced reliability, including improved expansion resistance on the Z-axis.

The risk of not doing so： Problems of electrical connectivity in the process of hole blowing or degassing (inner layer separation, hole wall fracture), or faults may occur under load conditions in actual use. IPCClass2 (the standard used in most factories) requires 20% less copper plating.

2. No welding repair or repair of broken repair line

Benefits: Perfect circuit ensures reliability and safety, no maintenance, no risk

The risk of not doing so：If not properly repaired, it will cause circuit board circuit break. Even if the repair is’ proper ‘, there is a risk of failure under load conditions (vibration, etc.), which may result in failure in actual use.

3. Exceed the cleanliness requirements of IPC specification

Benefit: Improved PCB cleanliness leads to improved reliability.

The risk of not doing so：Accumulation of residue and solder on the circuit board poses a risk to the welding layer, and ionic residue can lead to corrosion and contamination risks 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: Solderability, reliability, and reduced risk of moisture intrusion

The risk of not doing so：Solder problems may occur due to metallographic changes in the surface treatment of older circuit boards, while moisture intrusion may lead to layering, inner layer and hole wall separation (open circuit) problems during assembly and/or actual use.

5. Use internationally known substrates — do not use “local” or unknown brands

Benefits: Improved reliability and known performance

The risk of not doing so：Poor mechanical properties mean that circuit boards do not perform as expected under assembly conditions. For example, high expansion properties can lead to layering, circuit breaking, and warping problems. Weakening of electrical characteristics can result in poor impedance performance.

6. The tolerance of copper-clad plates conforms to the requirements of IPC4101ClassB/L

Advantage: Strict control of dielectric thickness can reduce the deviation of expected value of electrical performance.

The risk of not doing so：Electrical performance may not meet specified requirements, and the same batch of components may have significant differences in output/performance.

7. Define welding resistance materials to ensure that they meet ipC-SM-840CLASST requirements

Benefits: XPCB Group recognizes “superior” inks to ensure ink safety and to ensure that unsolder 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 can cause the solder mask to detach from the circuit board and eventually lead to corrosion of the copper circuit. Poor insulation can cause short circuit by accidental electrical connectivity/arc.

8. Define tolerances for outline, holes and other mechanical features

Benefits: Strict tolerance control improves dimensional quality – improves fit, shape and function

The risk of not doing so：Problems during assembly, such as alignment/fit (problems with press fit needles are not found until assembly is complete). In addition, due to the increase in size deviation, loading base will also be a problem.

9. XPCB specifies the thickness of the solder mask, although IPC does not

Benefits: Improved electrical insulation reduces the risk of flaking or loss of adhesion, and enhances the ability to withstand mechanical impact wherever it occurs!

The risk of not doing so：The thickness of the resistance layer can lead to adhesion, flux resistance and hardness problems. All of these problems can cause the solder mask to detach from the circuit board and eventually lead to corrosion of the copper circuit. Poor insulation due to thin resistance layer, short circuit due to accidental conduction/arc.

10. Appearance requirements and repair requirements are defined, although IPC is not

Benefits: In the manufacturing process of careful care and carefully cast safety.

The risk of not doing so：A variety of scrapes, minor injuries, repairs and repairs – boards work but don’t look good. In addition to the apparent problems, 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 plugs will reduce the risk of failure during assembly.

The risk of not doing so：The chemical residue in the process of gold deposition may be left in the hole of the plug hole, thus causing problems such as weldability. The holes may also contain tin beads, which may spatter out during assembly or actual use, causing a short circuit.

12. PetersSD2955 specifies the brand and model of peeling blue glue

Benefit: The designation of bluefin glue avoids the use of “local” or cheap brands.

The risk of not doing so：Poor quality or cheap degumming may bubble, melt, break, or solidify like concrete during assembly, rendering degumming impossible/inoperative.

13. XPCB performs a specific approval and ordering procedure for each purchase order

Benefit: This procedure is executed to ensure that all specifications have been validated.

The risk of not doing so：If product specifications are not carefully confirmed, the resulting deviation may not be detected until assembly or final production, when it is too late.

14. Sleeve plates with scrap units are not acceptable

Benefit: Eliminating partial assembly helps customers improve efficiency.

The risk of not doing so：Defective sleeve plates require a special assembly procedure, and if the scrap unit plate (X-out) is not clearly marked or isolated from the sleeve, it is possible to assemble a known defective plate, thus wasting parts and time.