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Comparison of advantages and disadvantages between three different materials of circuit boards
2021-09-29
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Author:Belle

According to the PCB industry forecast and prospect analysis report released by Zhiyan Consulting, the current domestic high-end circuit board products still account for a relatively low proportion, especially in the aspect of packaging substrates. Compared with Japan and other countries, domestic circuits Board manufacturers produce more low-end, low-value-added products, and there is still a gap in technology. The thermal conductivity of circuit boards is related to the materials of their products. Choosing substrates of different materials is a trend currently under development. Otherwise, ceramic substrates cannot stand out.


A comparison of the material of the circuit board itself on the market

There are three types of PCBs that are better developed in the market, one is FR-4 copper clad laminate, the other is metal substrate, and the last is ceramic circuit board. The FR-4 circuit board is currently the most widely used on the market, but the defects of the FR-4 circuit board are irreversible afterwards.


Based on years of experience in circuit board production by our technical staff, a simple analysis of the circuit boards on the market has been made,

(1) Advantages of fr-4 copper clad laminate:

1. No insulating layer is used.

2. Mass production.

3. Fast forming.

4. The price is low.

There are almost 12 kinds of defects:


  1. The more common thickness tolerances are medium thickness and thin surroundings, or thick on one side and thin on the other. It will affect the processing of the pcb, and the uneven thickness will affect the depth of the slot. The resistance of the substrate. For the more precise printed circuit board, the thick board will cause the tightness of the plug when the whole machine is not uniform, resulting in poor contact . Affect the performance of electronic devices. For multi-layer printed circuit boards, the accumulation of thickness tolerances may cause the entire thickness of the entire board to be too poor and cause waste. Can not meet the tolerance requirements of the test platform and other high-precision products for the thick bottom of the high-pressure plate.

     

2. Substrate fluttering: it affects the solder resistance, electrical insulation and many other properties of the substrate and cannot be used as a genuine product.

3. Substrate delamination: This phenomenon is not impossible to apply, but cannot be a Class A product.

4. White spots and white lines on the substrate: seriously affect the quality of PCB manufacturing


circuit boards

5. The exposed pattern of the substrate: cause the insulation performance to decline, and seriously affect the quality of the pcb board

6. Substrate impurities and black spots: In addition to affecting the appearance of the product, there are other effects. What can be done now is

7. Copper foil creases: those with such creases are not allowed to be used in pcb production


8. Glue point: is the cured resin. During the production process, it cannot be corroded. Seriously affect the insulation between wires. So it cannot be used for pcb production.

9. Pit: It has a great impact on the quality of pcb products, and may cause the line to be blocked or seem to be blocked.

10. Pinholes: will cause rough images, with traces of kerosene leakage.


11. Copper foil oxidation: slight oxidation will not affect the quality of pcb products, but it should be prevented as much as possible. Severe oxidation may cause the PCB manufacturing process to be difficult to corrode and clean, and cannot be used for the production of copper clad laminates.


12. Bright spot of copper foil: Because the anti-oxidation layer is destroyed at this point, this point is easy to be oxidized during the storage process of the product, which will cause adverse effects on the pcb. For larger bright spots, the copper and tin in this place may be thinner than other places, and it will also affect the manufacturing quality of pcb.

13. Light concave, as long as it appears once, there will be many consecutively, which will not be accepted by the manufacturer.


14. Steel plate pattern, copper clad laminate with steel plate pattern will cause wave pattern on the copper foil surface for fine line PCB production, which is obviously not allowed.

15. The uneven filling problem has an impact on the insulation performance and mechanical processing performance of the pcb.

16. The problem of insufficient curing of the substrate, the mechanical strength of the substrate is reduced, the white circle of the substrate punching is more obvious, and the edge burr is more.


17. Common defects of prepreg.

18. CAF (substrate resistance to ion migration problem) will cause a large error in copper ion thickness coverage in PCB processing.


(2) Advantages of aluminum substrate:


1. It is more suitable for SMT process;

2. Meet the requirements of RoHs;


3. The heat dissipation has been effectively treated, thereby reducing the operating temperature of the module, extending the service life and improving the reliability;

4. The volume is decreasing, reducing the assembly area of radiators and other hardware (including thermal interface materials), reducing product volume, and reducing hardware and assembly costs;


5. Good mechanical durability, better than ceramic circuit boards made by some simple processes.

Disadvantages of aluminum substrate:


1. Higher cost: Compared with other affordable products, the price of aluminum substrates accounts for more than 30% of the product price, which does not meet the standard.

2. At present, the mainstream can only make single-sided panels, and it is difficult to make double-sided panels. At present, the domestic single-panel is relatively skilled, and the process and technology of the multilayer board is relatively mature in foreign countries, and more people will come to understand.


3. The products made are more prone to problems in terms of electrical strength and withstand voltage: this problem is mainly related to the material itself.

4. Aluminum base will have an impact on the withstand voltage index of the board; the value of the withstand voltage of the whole lamp and the withstand voltage of the aluminum substrate does not meet the standard; the circuit design and structural design have an impact on the withstand voltage, and some applications in the market are used in LEDs. The measured withstand voltage of the aluminum substrate in the lamp can't exceed 800V.


5. The thermal conductivity test method and the test result do not match. The thermal conductivity of the dielectric layer is different from the thermal conductivity of the finished aluminum substrate.


6. The material specifications for aluminum-based copper clad laminates are not unified. There are CPCA industry standards, national standards, international standards, etc.

7. If the thickness of the copper foil does not meet the standard, it will cause some phenomena such as burning the circuit and exploding the power supply.

8. There are more and more pcb manufacturers, and the counterfeit products are disrupting the situation, cutting corners, using shoddy goods to replace good ones.


(3) Advantages of ceramic circuit board:

1. High resistance.

2. Outstanding high frequency characteristics.

3. Has high thermal conductivity: It is related to the material itself, ceramics have advantages over metals and resins.

3. Good chemical stability, anti-vibration, heat resistance, pressure resistance, internal circuits, MARK points, etc. are better than general circuit substrates.

4. It is more accurate in printing, patching and welding.


Disadvantages of ceramic plates:

1. Fragile: This is one of the most important shortcomings. At present, only small-area circuit boards can be produced.

2. Expensive: There are more and more requirements for electronic products. Ceramic circuit boards only meet the requirements of some relatively high-end products, and low-end products will not be used at all.