At first glance, PCBs are almost the same regardless of their inherent quality. It is through the surface that we see the differences, and these differences are critical to the durability and function of the PCB throughout its life.
Whether it is in the manufacturing assembly process or in actual use, PCB must have reliable performance, which is very important. In addition to related costs, defects in the assembly process may be brought into the final product by the PCB, which may fail during actual use, resulting in claims. Therefore, from this point of view, it is no exaggeration to say that the cost of a high-quality PCB is negligible.
In all market segments, especially those that produce products in key application areas, the consequences of such failures are unimaginable.
When comparing PCB prices, these aspects should be kept in mind. Although the initial cost of a reliable, guaranteed and long-life product is relatively high, it is worth the money in the long run.
14 most important features of high reliability circuit boards
1. 25 micron hole wall copper thickness
benefit
Enhanced reliability, including improved z-axis expansion resistance.
The risk of not doing this
Blowing holes or degassing, electrical connectivity problems during assembly (inner layer separation, hole wall breakage), or failures under load conditions during actual use. IPCClass2 (the standard adopted by most factories) requires 20% less copper plating.
2. No welding repair or broken line repair
benefit
Perfect circuit ensures reliability and safety, no maintenance, no risk
The risk of not doing this
If not repaired properly, it will cause the circuit board to open. Even if the repair is 'proper', there is a risk of failure under load conditions (vibration, etc.), which may cause failure in actual use.
3. Cleanliness requirements that exceed IPC specifications
benefit
Increasing PCB cleanliness can increase reliability.
The risk of not doing this
The residue and solder accumulation on the circuit board pose a risk to the solder mask. Ion residue will lead to corrosion and contamination risks on the soldering surface, which may lead to reliability problems (bad solder joints / electrical failures) and eventually increase the occurrence of actual failures. Probability.
4. Strictly control the service life of each surface treatment
benefit
Solderability, reliability, and reduce the risk of moisture intrusion
The risk of not doing this
Due to the metallographic changes in the surface treatment of the old circuit board, solderability problems may occur, and moisture intrusion may cause problems such as delamination, separation of the inner layer and the hole wall (open circuit) during the assembly process and / or actual use .
5. Use internationally renowned substrates – do not use local or unknown brands
benefit
Improve reliability and known performance
The risk of not doing this
Poor mechanical performance means that the circuit board cannot perform its expected performance under assembly conditions. For example, higher expansion performance can cause delamination, open circuit, and warpage problems. Weakened electrical characteristics can lead to poor impedance performance.
6. Tolerance of copper clad laminate meets IPC4101ClassB / L requirements
benefit
Strict control of the thickness of the dielectric layer can reduce the deviation of the expected value of electrical performance.
The risk of not doing this
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 solder resist materials to ensure compliance with IPC-SM-840ClassT requirements
benefit
NCAB Group recognizes excellent inks to achieve ink safety and ensure that solder mask inks meet UL standards.
The risk of not doing this
Poor quality ink can cause adhesion, flux resistance and hardness problems. All of these problems will cause the solder mask to detach from the circuit board and eventually lead to corrosion of the copper circuit. Poor insulation properties can cause short circuits due to unexpected electrical connectivity / arc.
8. Define the tolerances of shape, hole and other mechanical features
benefit
Strict control of tolerances can improve the dimensional quality of products-improve fit, shape and function
The risk of not doing this
Problems during assembly, such as alignment / fitting (only problems with press-fit pins will be discovered when the assembly is complete). In addition, due to the increased dimensional deviation, there will be problems with the base.
9. NCAB specifies the thickness of the solder mask, although IPC has no relevant regulations
benefit
Improve electrical insulation characteristics, reduce the risk of flaking or loss of adhesion, and strengthen the ability to resist mechanical impact forces-no matter where the mechanical impact forces occur!
The risk of not doing this
Thin solder masks can cause adhesion, flux resistance, and hardness issues. All of these problems will cause the solder mask to detach from the circuit board and eventually lead to corrosion of the copper circuit. The insulation properties are poor due to the thin solder mask, which can cause short circuits due to unexpected conduction / arc.
10. The appearance requirements and repair requirements are defined, although IPC does not define
benefit
Careful care and careful casting of safety during the manufacturing process.
The risk of not doing this
A variety of scratches, minor damages, repairs and repairs-circuit boards can be used but not good-looking. In addition to the problems that can be seen on the surface, what other unseen risks, as well as the impact on assembly and the risks in actual use?
11. Depth of plug hole
benefit
High quality plug holes will reduce the risk of failure during assembly.
The risk of not doing this
The chemical residues in the gold sinking process may remain in the holes with dissatisfied plug holes, thereby causing solderability and other problems. Moreover, tin beads may be hidden in the holes. During assembly or actual use, the tin beads may splash out, causing a short circuit.
12, PetersSD2955 specifies the brand and model of peelable blue glue
benefit
The designation of peelable blue glue can avoid the use of local or cheap brands.
The risk of not doing this
Inferior or cheap peelable glue may foam, melt, crack, or solidify like concrete during assembly, making the peelable glue not peelable / ineffective.
13. NCAB executes specific approval and order placement procedures for each purchase order
benefit
The execution of this procedure ensures that all specifications have been confirmed.
The risk of not doing this
If product specifications are not carefully confirmed, the resulting deviation may not be discovered until the assembly or final product, which is too late.
14. Do not accept sets with scrap units
benefit
Not using local assembly can help customers improve efficiency.
The risk of not doing this
Defective panels require special assembly procedures. If it is not clear that the scrapped unit board (x-out) is marked or if it is not isolated from the panel, it is possible to assemble this known bad panel Waste parts and time.
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