Fourteen important features of highly reliable PCB

- Nov 03, 2018-

At first glance, PCB looks pretty much the same regardless of its intrinsic quality.It is through the surface that we see differences that are critical to PCB durability and functionality throughout its life.

It is critical that PCB have reliable performance both in manufacturing and in practical use.In addition to the relevant costs, defects in the assembly process may be brought into the final product by the PCB and may malfunction during actual use, leading to claims.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 that produce products in key application areas, the consequences of such failures are unthinkable.

Keep these in mind when comparing PCB prices.Although reliable, guaranteed and long-life products have higher initial costs, they are still worth the money in the long run.

14 of the most important features of the highly reliable circuit board

Copper thickness of hole wall of 1, 25 micron

Benefits: increased reliability, including improved z-axis expansion resistance.

The risk of not doing so

Blow-through or degassing, electrical connectivity problems during assembly (inner separation, hole wall rupture), or failure may occur under load conditions during actual use.IPCClass2 (the standard used by most factories) requires 20% less copper plating.

2. No welding repair or broken repair

Benefit: perfect circuit ensures reliability and safety, no maintenance, no risk

The risk of not doing so

If not repaired properly, the circuit board can be broken.Even if the repair is' appropriate ', there is a risk of failure under load conditions (vibration, etc.), which may occur in actual use.

3. Cleanliness beyond IPC specification

Benefit: improving PCB cleanliness increases reliability.

The risk of not doing so

The residue and solder accumulation on the circuit board will bring risk to the welding layer, and the ion residue will lead to the risk of welding surface corrosion and pollution, which may lead to reliability problems (bad solder spot/electrical fault) and eventually increase the probability of actual fault.

4. Strictly control the service life of each surface treatment

Benefits: solderability, reliability, and reduced risk of moisture invasion

The risk of not doing so

Solderability problems may occur due to metallographic changes in the surface treatment of the old circuit boards, and moisture intrusion may lead to problems such as delamination, inner layer and hole wall separation (disconnection) 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 performance means that the circuit board cannot perform its expected performance under assembly conditions, for example, high expansion performance will lead to delamination, circuit breaking and warping problems.Weakened electrical characteristics can lead to poor impedance performance.

6. The copper clad plates meet the IPC4101ClassB/L requirements

Benefits: strict control of dielectric thickness can reduce the expected value deviation of electrical performance.

The risk of not doing so

The electrical performance may not meet the specified requirements, and the same batch of components will differ greatly in output/performance.

7. Define the resistance welding materials to ensure compliance with ipc-sm-840classt requirements

Benefits: NCAB group recognizes "excellent" inks for ink security, ensuring that the solder mask inks meet UL standards.

The risk of not doing so

Poor quality ink can lead to adhesion, flux resistance and hardness problems.All these problems will cause the solder layer to break away from the circuit board and eventually lead to copper circuit corrosion.Poor insulation can be short-circuited due to accidental electrical connectivity/arcing.

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

Benefits: strict control of tolerances improves product size - improving fit, shape and function

The risk of not doing so

Problems with the assembly process, such as alignment/alignment (problems with the press fit needle will only be found when the assembly is completed).In addition, due to the size deviation increase, loading base will also have problems.

9. NCAB specifies the thickness of the resistance welding layer, although IPC does not have relevant regulations

Benefits: improved electrical insulation, reduced risk of spalling or loss of adhesion, and enhanced ability to combat mechanical shock wherever it occurs!

The risk of not doing so

The thin resistance layer can lead to adhesion, flux resistance and hardness problems.All these problems will cause the solder layer to break away from the circuit board and eventually lead to copper circuit corrosion.Poor insulation due to thin resistance layer, short circuit due to accidental conduction/arc.

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

Benefit: carefully care and carefully cast safety during manufacturing.

The risk of not doing so

Multiple abrasions, minor injuries, repairs and repairs - circuit boards can be used but do not look good.In addition to the problems that can be seen on the surface, what are the risks that can't be seen, the impact on assembly, and the risks that are actually in use?

11. Requirements for the depth of plug hole

Benefit: high quality plug holes reduce the risk of failure during assembly.

The risk of not doing so

The unsatisfied hole can residues the chemical residue in the process of gold precipitation, which leads to problems of solderability and so on.Tin beads may also be hidden in the hole, and during assembly or actual use, they may spill out and cause a short circuit.

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

Benefits: designable bluestones can avoid the use of "local" or cheap brands.

The risk of not doing so

Bad or cheap stripping during assembly may blister, melt, fracture or solidify like concrete, making stripping impossible/ineffective.

13. NCAB performs specific approval and ordering procedures for each purchase order

Benefit: execution 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 discovered until assembly or final product, when it is too late.

14. The cover plate with scrapped units is not acceptable

Benefits: avoiding partial assembly helps customers improve efficiency.

The risk of not doing so

Defective shutters require special assembly procedures. If the dead cell plate (x-out) is not clearly marked or is not isolated from the shutters, it is possible to assemble the known broken plate, thus wasting parts and time.