At first glance, PCBs are almost the same on the surface, regardless of their internal quality. It is through the surface that we see the differences that are crucial to the durability and function of the PCB throughout its life.
Whether it is in the manufacturing and assembly process or in actual use, PCB should have reliable performance, which is very important. In addition to the related costs, the defects in the assembly process may be brought into the final product by PCB, and failure may occur in the actual use process, leading to claims. Therefore, from this point of view, it is not too much to say that the cost of a high-quality PCB can be ignored.
In all segments, especially in markets where products in key applications are produced, the consequences of such failures are unthinkable.
These aspects should be kept in mind when comparing PCB prices. Although the initial cost of reliable, guaranteed and long-life products is high, it is still worth it in the long term.
14 most important features of high reliability circuit board
1. 25 micron copper thickness on the wall of the hole
benefit
Enhance reliability, including improvement of the expansion resistance of z-axis.
Risk of not doing so
The electrical connectivity problems (inner layer separation, hole wall fracture) during blowing or degassing and assembly, or failure under load conditions in actual use. Ipclas2 (the standard used in most factories) requires less than 20 percent copper plating.
2. No welding repair or open circuit repair
benefit
Perfect circuit ensures reliability and safety, no maintenance, no risk
Risk of not doing so
If the repair is not correct, the circuit board will open. Even if the repair is “proper”, there is a risk of failure under load conditions (vibration, etc.), which may occur in actual use.
3. Exceeding the cleanliness requirements of IPC specification
benefit
Improve PCB cleanliness can improve reliability.
Risk of not doing so
The residual and solder accumulation on the circuit board will bring risks to the welding layer, and the ion residue will lead to the risk of corrosion and pollution on the welding surface, which may lead to reliability problems (bad solder joints / electrical faults), and finally increase the probability of actual failure.
4. Strictly control the service life of each surface treatment
benefit
Solder, reliability and reduce risk of moisture intrusion
Risk of not doing so
Because of the metallographic changes of the surface treatment of the old circuit board, solder tin problem may occur, while moisture intrusion may lead to delamination, inner layer and hole wall separation (open circuit) during assembly and / or actual use.
5. Use internationally renowned substrates – do not use “local” or unknown brands
benefit
Improve reliability and known performance
Risk of not doing so
Poor mechanical performance means that the circuit board can not perform its expected performance under assembly conditions, for example, higher expansion performance can lead to delamination, open circuit and warping problems. The weakening of electrical characteristics can lead to poor impedance performance.
6. Tolerance of copper clad plate shall meet the requirements of ipc4101classb/l
benefit
Strictly controlling the thickness of dielectric layer can reduce the deviation of expected value of electrical performance.
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 greatly different.
7. Define welding resistance materials to ensure compliance with ipc-sm-840class requirements
benefit
NCAB Group recognizes “excellent” ink, realizes ink safety, and ensures that the solder layer ink meets UL standards.
Risk of not doing so
Poor quality ink can lead to adhesion, flux resistance and hardness problems. All these problems will lead to the separation of the solder layer from the circuit board and eventually lead to copper circuit corrosion. Poor insulation properties can be short circuited due to unexpected electrical connectivity / arc.
8. Tolerances defining profiles, holes and other mechanical characteristics
benefit
Strict tolerance control improves product size quality – improved fit, shape and function
Risk of not doing so
Problems during assembly, such as alignment / fit (only when assembly is complete will the problem of press fit pin be found). In addition, due to the increase of the dimension deviation, there will be problems in the installation of the base.
9. NCAB specifies the thickness of the weld barrier, although IPC does not have relevant provisions
benefit
Improved electrical insulation properties, reduced risk of peeling or loss of adhesion, enhanced the ability to resist mechanical impact – wherever mechanical impact occurs!
Risk of not doing so
The thin layer of the welding resistance can lead to adhesion, flux resistance and hardness problems. All these problems will lead to the separation of the solder layer from the circuit board and eventually lead to copper circuit corrosion. Poor insulation due to thin welding resistance layer, short circuit due to accidental conduction / arc.
10. The appearance and repair requirements are defined, although not defined by the IPC
benefit
Carefully care and carefully cast safety during manufacturing.
Risk of not doing so
A variety of scratches, minor damage, repairs and repairs – boards can be used but not good looking. What are the risks that are not visible, the impact on assembly and the risks in use, in addition to the surface visible issues?
11. Requirements for the depth of plug hole
benefit
High quality plug holes will reduce the risk of failure during assembly.
Risk of not doing so
The chemical residue in the gold deposit process can be left in the hole with dissatisfaction of plug hole, which causes weldability and other problems. And the holes may also contain tin beads. In assembly or actual use, solder beads may splash out, causing short circuit.
12. Peterssd2955 specifies the brand and model of strippable blue glue
benefit
The designation of stripable blue glue avoids the use of “local” or cheap brands.
Risk of not doing so
Poor or cheap strippable adhesive may blister, melt, break or solidify as concrete during assembly, making it impossible / ineffective.
13. NCAB performs specific approval and order procedures for each purchase order
benefit
The implementation of this procedure ensures that all specifications have been confirmed.
Risk of not doing so
If the product specification is not confirmed carefully, the deviation may not be found until assembly or final product, which is too late.
14. Do not accept the cover plate with scrap unit
benefit
Not using local assembly can help customers improve efficiency.
Risk of not doing so
The defective sleeve plate requires special assembly procedure. If it is not clearly marked with the scrap unit board (x-out), or it is not isolated from the sleeve plate, it is possible to assemble the known bad plate, thus wasting parts and time.