At first glance, regardless of the inherent quality of PCB, they are similar in surface. If we look hard, we see the difference through the surface, and these differences are critical to the durability and functionality of the PCB throughout its life.
    Whether it is in manufacture and assembly process or in actual use, PCB must have a reliable performance, this is very essential. Inaddition to the associated costs, defects in the assembly process may be brought into the final product by the PCB, and in the actual use it may cause malfunction, resulting in claims. Therefore, from this point of view, it is not ovely to say that the cost of a high-quality PCB is negligible. In all specific market,especially in the market of key application, the consequences of such malfunction can be disastrous.

    When comparing PCB prices, keep these aspects in mind. Although reliable, guaranteed and long-lived products, the initial cost is higher, but in the long run or value for money. Here's a look at the 14 most important features of a high-reliability circuit board:

1,25 micron hole wall copper thick
Benefits: Enhanced reliability, including improved z-axis resistance to expansion.
Risk of doing so: blown holes or degassing, electrical connectivity problems during assembly (inner layer separation, hole wall breakage), or failure in actual conditions under load conditions. IPCClass2 (the standard used in most plants) requires 20% less copper plating.

2, no welding repair or broken line repair line
Benefits: Perfect circuit ensures reliability and safety, no maintenance, no risk
Do not do the risk: If the repair is not correct, it will cause the circuit board to open. Even if the repair of 'properly', under load conditions (vibration, etc.) there will be a risk of failure, which may occur in actual use failure.

3, beyond the cleanliness of the IPC specification requirements
Benefits: Increased PCB cleanliness improves reliability.
Risk of doing so: Residual on the board, solder buildup poses a risk to the solder mask, which can lead to welding surface corrosion and contamination risks, which can lead to reliability problems (poor solder joint / electrical failure) and And ultimately increase the probability of occurrence of actual failure.

4, strictly control the life of each surface treatment
Benefits: Solderability, reliability, and reduced risk of moisture intrusion
The risk of doing so is that there is a possibility of solderability due to metallographic changes in the surface treatment of the old circuit board, and moisture intrusion may result in stratification, inner and pore walls in the assembly process and / or actual use Separation (open circuit) and other issues.

5, the use of internationally renowned substrate - do not use the "local" or unknown brand
Benefits: Increased reliability and known performance
The risk of doing so: poor mechanical performance means that the circuit board can not perform the intended performance under assembly conditions. For example, higher expansion properties can lead to delamination, breakage and warping problems. Reduced electrical properties can lead to poor impedance performance.

6, CCL tolerances in line with IPC4101ClassB / L requirements
Benefits: Strict control of the thickness of the dielectric layer can reduce the expected deviation of electrical performance.
Do not do the risk: electrical performance may not meet the requirements, the same batch of components in the output / performance will be quite different.

7, define the solder mask material, to ensure compliance with IPC-SM-840ClassT requirements
Benefits: "excellent" ink, to achieve ink safety, to ensure that solder mask ink in line with UL standards.
Do not do the risk: poor quality ink can lead to adhesion, flux resistance and hardness problems. All of these problems will lead to solder mask and circuit board detachment, and eventually lead to corrosion of copper circuit. Poor insulation may result in short circuit due to unexpected electrical connectivity / arc.

8, to define the shape, holes and other mechanical characteristics of the tolerance
Benefits: Strict control of tolerances improves product size and quality - Improved fit, shape and function
Do not do the risk of assembling the process, such as alignment / matching (only when the assembly is completed will find the problem with the press fit). In addition, due to increased size deviation, loading the base will be a problem.

9, the thickness of the solder mask requirements, although the IPC is not relevant
Benefits: Improves electrical insulation, reduces the risk of peeling or loss of adhesion, and strengthens the ability to fight mechanical shocks - no matter where the mechanical impact occurs!
Do not do this risk: solder mask thin can lead to adhesion, flux resistance and hardness problems. All of these problems will lead to solder mask and circuit board detachment, and eventually lead to corrosion of copper circuit. Due to poor solder mask caused by poor insulation properties, due to accidental conduction / arc caused by short circuit.

10, defines the appearance requirements and repair requirements, although the IPC is not defined
Benefits: Careful care and seriousness in the manufacturing process.
Do not do the risk: a variety of abrasions, small damage, repair and repair - the circuit board can be used but does not look good. What are the risks that can not be seen, as well as the impact on assembly, and the risks in actual use, in addition to the problems that can be seen on the surface?

11, the requirements of the depth of the hole in printed circuit board
Benefits: High quality plug holes will reduce the risk of failure during assembly.
Do not do the risk: plug holes dissatisfied with the hole in the residual gold in the process of chemical residues, resulting in solderability and other issues. And the hole may also be hidden in the tin beads, in the assembly or the actual use of tin beads may splash out, resulting in short circuit.

12, designated stripe blue plastic brand and model
Benefits: Can be stripped of blue plastic to avoid the use of "local" or cheap brand.
The risk of doing so: Poor or inexpensive peelable glue may cause foaming, melting, cracking, or solidification like concrete during assembly, so that stripping does not peel off / does not work.

13, the implementation of specific orders for each purchase orders and orders procedures
Benefits: The implementation of the program ensures that all specifications have been confirmed.
Do not do the risk: If the product specifications are not carefully confirmed, which caused the deviation may be to the assembly or the final product was found, and this time too late.

14, do not accept the scrapped units of the plate
Benefit: Do not use local assembly to help customers improve efficiency.
    Do not do the risk: a defective board requires a special assembly procedure. If it is unclear to indicate that the waste unit board (x-out) is not isolated from the board, it is possible to assemble this Know bad boards, thus wasting parts and time.