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PCB Technical

PCB Technical - Inventory of the fourteen important characteristics of high reliability of PCB high-frequency boards

PCB Technical

PCB Technical - Inventory of the fourteen important characteristics of high reliability of PCB high-frequency boards

Inventory of the fourteen important characteristics of high reliability of PCB high-frequency boards

2021-09-09
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Author:Belle

At first glance, the PCB high-frequency board looks the same regardless of its internal quality. It is through the surface that we see the differences, and these differences are critical to the durability and functionality of the PCB throughout its life.


Whether 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 high-frequency board, and failures may occur during actual use, leading to claims. Therefore, from this point of view, it is no exaggeration to say that the cost of a high-quality PCB high-frequency board is negligible. In all market segments, especially those that produce products in key application areas, the consequences of such failures are disastrous.


These aspects should be kept in mind when comparing the price of PCB high-frequency boards. Although the initial cost of reliable, guaranteed, and long-life products is high, they are still worth the money in the long run. Let's take a look at the 14 most important characteristics of high-reliability circuit boards:


1. The copper thickness of the hole wall of the PCB high-frequency board is 25 microns


benefit:

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


Risks of not doing this:

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


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2. Exceeding the cleanliness requirements of IPC specifications


benefit

Improving the cleanliness of PCB high-frequency boards can improve reliability.


The risk of not doing so

Residues and solder accumulation on the high-frequency 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 actual Probability of failure.


3. 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.


The 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.


iPCB is mainly engaged in the production services of high-frequency microwave radio frequency induction printed circuit boards and double-sided multilayer circuit boards for quick samples and small and medium batches. The main products are: PCB high frequency board, Rogers circuit board, high frequency circuit board, high frequency microwave board, microwave radar antenna board, microwave radio frequency high frequency board, microstrip circuit board, antenna circuit board, heat dissipation circuit board, high frequency and high speed Circuit board, Rogers/Rogers high-frequency board, ARLON high-frequency board, mixed dielectric laminate, special circuit board, F4B antenna board, antenna ceramic board, radar sensor PCB, special circuit board manufacturer, pair of slot antenna, RF antenna, broadband Antennas, frequency sweep antennas, microstrip antennas, ceramic antennas, power splitters, couplers, combiners, power amplifiers, dry amplifiers, base stations, etc.


4. Defining the tolerances of shapes, holes 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 so


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


5. Use internationally well-known substrates-do not use "local" or unknown brands

benefit

Improve reliability and known performance

The 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 will cause delamination, disconnection and warpage problems. Weakened electrical characteristics can lead to poor impedance performance.


6. No welding repair or open circuit repair

benefit:

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


The risk of not doing so

If repaired improperly, it will cause the PCB high-frequency board 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.


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

benefit

"Excellent" ink, to achieve ink safety, to ensure that the solder mask ink meets UL standards.


The 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 accidental electrical continuity/arc.


8. Strictly control the service life of each surface treatment

benefit

Solderability, reliability, and reduce the risk of moisture intrusion


The risk of not doing so

Due to the metallographic changes in the surface treatment of 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.


9. Requirements for 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!


The 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.

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

benefit

Careful care and carefulness in the manufacturing process create safety.

The risk of not doing so


A variety of scratches, minor damages, repairs and repairs-PCB high-frequency 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 assembly, and the risks in actual use?


11. Implement specific approval and order procedures for each purchase order

benefit

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

The risk of not doing so


If the specifications of the PCB high-frequency board are not carefully confirmed, the deviations caused by this may not be discovered until the assembly or the final product, and it is too late at this time.


12. Specify 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 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.


13. Requirements for the depth of the plug hole

benefit

The high-quality plug holes of the PCB high-frequency board will reduce the risk of failure during the assembly process.

The risk of not doing so


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


14. Do not accept boards with scrapped units

benefit

Not using partial assembly can help customers improve efficiency.

The risk of not doing so


A board with defects requires special assembly procedures. If it is not clear to mark the scrap unit board (x-out), or if it is not isolated from the board, it is possible to assemble this known bad board. Waste parts and time.