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PCB기술

PCB기술

PCB기술

PCB기술

The features of high reliability PCB
2020-09-22
View:186
Author:Annie      Share

1. Use internationally well-known 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 cannot perform the expected performance under assembly conditions. For example, high expansion performance can cause delamination, disconnection and warpage. Weakened electrical characteristics can lead to poor impedance performance.

2. 25 micron hole wall copper thickness

Benefit:

Enhance reliability, including improving the expansion resistance of the z-axis.

Risk of not doing so:

Blow holes or degassing, electrical connectivity problems during assembly (inner layer separation, hole wall fracture), or failures under load conditions in actual use. IPCClass2 (the standard adopted by most factories) requires 20% less copper plating.

3. No welding repair or open circuit repair

Benefit:

Perfect circuit can ensure reliability and safety, no maintenance, no risk

Risk of not doing so:

If repaired improperly, the circuit board will be broken. Even if the repair is ‘proper’, there is a risk of failure under load conditions (vibration, etc.), which may cause failure in actual use.

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4. Requirements for the depth of the plug hole

Benefit:

High-quality plug holes will reduce the risk of failure during assembly.

Risk of not doing so:

The chemical residues in the gold-immersion process may remain in the hole that is not full of the plug hole, causing problems such as solderability. Moreover, there may be tin beads hidden in the holes, which may splash out during assembly or actual use, causing short circuits.

5. Cleanliness requirements exceeding IPC specifications

Benefit:

Improving PCB cleanliness can increase reliability.

Risk of not doing so:

Residues and solder accumulation on the circuit board bring risks to the solder mask. Ionic residues can cause corrosion and contamination risks on the soldering surface, which may lead to reliability problems (bad solder joints/electrical failures) and ultimately increase the occurrence of actual failures Probability.

6. Lianshuo Circuit performs specific approval and ordering procedures for each purchase order

Benefit:

The execution of this program ensures that all specifications have been confirmed.

Risk of not doing so:

If the product specifications are not carefully confirmed, the resulting deviation may not be discovered until the assembly or the final product, and it is too late at this time.

7. Strictly control the service life of each surface treatment

Benefit:

Solderability, reliability, and reduce the risk of moisture intrusion

Risk of not doing so:

Due to the metallographic changes in the surface treatment of the old circuit boards, soldering problems may occur, and moisture intrusion may cause problems such as delamination, separation (open circuit) of the inner layer and the hole wall during the assembly process and/or actual use .

8. The tolerance of the copper clad laminate meets the requirements of IPC4101ClassB/L

Benefit:

Strictly controlling the thickness of the dielectric layer can reduce the deviation of expected 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 quite different.

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9. Define solder mask materials to ensure compliance with IPC-SM-840ClassT requirements

Benefit:

 ipcb Circuits recognizes "excellent" inks, realizes ink safety, and ensures that solder mask inks meet UL standards.

Risk of not doing so:

Inferior inks can cause adhesion, flux resistance and hardness problems. All these problems will cause the solder mask to separate from the circuit board, and eventually lead to corrosion of the copper circuit. Poor insulation properties can cause short circuits due to unexpected electrical continuity/arc.

10. Defining the tolerances of shapes, holes and other mechanical features

Benefit:

Strict tolerance control can improve the dimensional quality of products-improve fit, shape and function

Risk of not doing so:

Problems in the assembly process, such as alignment/fitting (the problem of press-fitting needles will only be discovered when the assembly is completed). In addition, due to the increased size deviation, there will be problems in installing the base.

11. Lianshuo Circuits specifies the thickness of the solder mask, although IPC does not have relevant regulations

Benefit:

Improve the electrical insulation properties, reduce the risk of peeling or loss of adhesion, and strengthen the ability to resist mechanical impact-no matter where the mechanical impact occurs!

Risk of not doing so:

Thin solder mask can cause adhesion, flux resistance and hardness problems. All these problems will cause the solder mask to separate from the circuit board, and eventually lead to corrosion of the copper circuit. Poor insulation properties due to the thin solder mask can cause short circuits due to accidental conduction/arc.

12. Appearance requirements and repair requirements are defined, although IPC does not define

Benefit

Careful care and carefulness in the manufacturing process create safety.

Risk of not doing so:

Various scratches, minor injuries, repairs and repairs-the circuit board works but doesn't look good. In addition to the problems that can be seen on the surface, what are the unseen risks, the impact on assembly, and the risks in actual use?

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 13. Sockets with scrap units are not accepted

Benefit:

Not using partial assembly can help customers improve efficiency.

Risk of not doing so:

A defective board requires a special assembly procedure. If it is not clear to mark the scrap unit board (x-out) or not isolate it from the board, it is possible to assemble this known bad board, thus Waste parts and time.

14. 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.

Risk of not doing so:

Inferior or cheap peelable glue may foam, melt, crack or solidify like concrete during the assembly process, making the peelable glue unable to peel off/not working.