PCB is almost the same on the surface regardless of its internal quality. It is through the surface that we see the differences, which are crucial to the durability and function of PCB in the whole life.
Whether in the manufacturing and assembly process or in practical use, PCB should have reliable performance, which is very important. In addition to relevant costs, defects in the assembly process may be brought into the final product by PCB, and faults may occur in the actual use process, resulting in claims. Therefore, from this point of view, it is not too much to say that the cost of a high-quality PCB is negligible.
In all market segments, especially those producing products in key application areas, the consequences of such failures are unimaginable.
These aspects should be kept in mind when comparing PCB prices. Although the initial cost of reliable, guaranteed and long-life products is high, they are worth it in the long run.
The 14 most important features of high reliability circuit boards are as follows:
1. 25 micron hole wall copper thickness
Benefits: increased reliability, including improved expansion resistance of the z-axis.
Risks of not doing so:
Electrical connectivity problems during hole blowing or degassing, assembly (inner layer separation, hole wall fracture), or faults may occur under load conditions during actual use. Ipcclass2 (the standard adopted by most factories) requires 20% less copper plating.
2. No welding repair or open circuit repair
Benefits: perfect circuit can ensure reliability and safety, no maintenance and no risk
Risks of not doing so:
If not repaired properly, the circuit board will be open circuit. 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 specifications
Benefits: improving PCB cleanliness can improve reliability.
Risks of not doing so:
The residue and solder accumulation on the circuit board will bring risks to the anti 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 joint / electrical failure), and finally increase the probability of actual failure.
4. Strictly control the service life of each surface treatment
Benefits: Solderability, reliability, and reduced risk of moisture intrusion
Risks of not doing so:
Due to metallographic changes in the surface treatment of old circuit boards, solder problems may occur, and moisture intrusion may lead to delamination, inner layer and hole wall separation (open circuit) in the assembly process and / or actual use.
5. Use internationally known substrates – do not use “local” or unknown brands
Benefits: improved reliability and known performance
Risks of not doing so:
Poor mechanical performance means that the circuit board cannot perform as expected under assembly conditions. For example, high expansion performance will lead to delamination, open circuit and warpage. The weakening of electrical characteristics can lead to poor impedance performance.
6. The tolerance of copper clad laminate shall meet the requirements of ipc4101classb / L
Benefits: strictly controlling the thickness of dielectric layer can reduce the deviation of expected value of electrical performance.
Risks of not doing so:
The electrical performance may not meet the specified requirements, and there will be great differences in output / performance of the same batch of components.
7. Define solder resist materials to ensure compliance with ipc-sm-840classt requirements
Benefits: NCAB Group recognizes “excellent” ink, realizes ink safety, and ensures that solder resist ink meets UL standards.
Risks of not doing so:
Poor quality inks can cause adhesion, flux resistance and hardness problems. All these problems will lead to the separation of the solder resist from the circuit board and eventually lead to copper circuit corrosion. Poor insulation characteristics can cause short circuits due to unexpected electrical connectivity / arcing.
8. Define tolerances for shapes, holes and other mechanical features
Benefits: strict tolerance control can improve the dimensional quality of products – improve fit, shape and function
Risks of not doing so:
The electrical performance may not meet the specified requirements, and there will be great differences in output / performance of the same batch of components.
Problems during assembly, such as alignment / fit (the problem of press fit needle will be found only after assembly is completed). In addition, there will be problems in mounting the base due to the increase of dimensional deviation.
9. NCAB specifies the thickness of solder resist, although IPC does not specify it
Benefits: improve electrical insulation properties, reduce the risk of peeling or loss of adhesion, and enhance the ability to resist mechanical impact – wherever mechanical impact occurs!
Risks of not doing so:
Thin solder resist layer can lead to adhesion, flux resistance and hardness problems. All these problems will lead to the separation of the solder resist from the circuit board and eventually lead to copper circuit corrosion. Poor insulation characteristics due to thin resistance welding layer can cause short circuit due to accidental conduction / arc.
10. Appearance and repair requirements are defined, although not defined by IPC
Benefits: careful care and care in the manufacturing process create safety.
Risks of not doing so:
A variety of scratches, minor damage, repair and repair – circuit boards can be used but not good-looking. In addition to the problems that can be seen on the surface, what are the invisible risks, the impact on the assembly and the risks in actual use?
11. Requirements for plug hole depth
Benefits: high quality plug holes will reduce the risk of failure during assembly.
Risks of not doing so:
Chemical residues in the gold precipitation process may remain in the holes with insufficient plug holes, resulting in problems such as weldability. In addition, tin beads may be hidden in the hole. During assembly or actual use, tin beads may splash out and cause short circuit.
12. Peterssd2955 specifies the brand and model of peelable blue glue
Benefits: the designation of peelable blue glue can avoid the use of “local” or cheap brands.
Risks of not doing so:
Inferior or cheap strippable glue may bubble, melt, crack or set like concrete during assembly, so that the strippable glue can not be stripped / ineffective.
13. NCAB implements specific approval and order placement procedures for each purchase order
Benefits: the implementation of this procedure ensures that all specifications have been confirmed.
Risks of not doing so:
If the product specification is not carefully confirmed, the resulting deviation may not be found until the assembly or final product, and then it is too late.
14. Sheathed plates with scrapped units are not acceptable
Benefits: not using partial assembly can help customers improve efficiency.
Risks of not doing so:
Special assembly procedures are required for defective sheathed boards. If the scrapped unit board (x-out) is not clearly marked or isolated from the sheathed board, it is possible to assemble this known bad board, thus wasting parts and time.
Nov. 17, 2021 
