1. Explanation of terms: Military grade A-grade sheet material: refers to the sheet with the highest grade of a sheet manufacturer, the insulation of the sheet, the uniformity of the sheet, the reliability of the copper skin and the sheet substrate, and the impedance stability of the sheet , far higher than the B-grade materials and C-grade materials in similar products, and can be used to produce military electronic products with absolutely demanding requirements!

　　Low-grade sheet B-grade material and C-grade material: sheet manufacturers, because of the low-cost demand of PCB circuit board manufacturers, produce sheet materials, this kind of sheet material, the sheet material manufacturers use shoddy and cut corners in the manufacturing process The situation! In terms of performance stability, the price of A-grade materials is far less than that of military-grade materials.

　　Second, the general plate manufacturers' plate grades are divided:

　　Grade A: The best grade board, meeting the military-grade requirements, industrial requirements, and quality assurance;

　　Class B: low-grade sheets are used for low-grade civilian use without quality assurance;

　　Grade C: The lower grade is entirely for cost, and there is no guarantee of quality.

　　Third, the composition of FR-4 (PCB circuit board) sheet

　　1. Glass fiber cloth;

　　2. Resin;

　　3. Copper foil.

　　Fourth, the comparison of materials used for different grades of plates and the hazards of low-grade plates:

　　Whether the application of glass fiber cloth copper foil resin sheet has the manufacturer's mark

　　A-grade material A-grade material generally uses 6-8 layers of glass fiber cloth, and uses a fine whole glass fiber cloth with excellent copper quality, and the thickness of copper foil will not shrink, which is excellent for industrial use. military marked

　　B-grade material B-grade material generally uses about 2 layers of glass fiber cloth, using ordinary glass fiber cloth, and the spliced rags of the glass fiber cloth are generally copper, and the thickness of the copper foil will be relatively low. Generally, the quality and stability requirements are not high. Civil none

　　C-grade material C-grade material generally uses about 2 layers of glass fiber cloth (the other parts are fillers, or are made of multiple pieces of rough glass fiber) The copper quality is poor, and the thickness of the copper foil will be relatively poor. can not be used on

　　The damage is because there is less glass fiber cloth and the glass fiber cloth is not good, which leads to 1) the poor glass fiber cloth is easy to fall off the pad, 2) the board is easy to bend, the glass fiber cloth is less, the tension is not enough, the board is bent, and the glass fiber is added. If the cloth is not good, it is very easy to cause the instability of electronic products, and the circuit is in a slightly off state! Copper foil, to put it bluntly, is your circuit, B-grade material and lower-grade C-grade material, use inferior copper foil, so as to Lead to inconsistent thickness of copper foil, inconsistent conductivity, and easy to fall off the pad. Resin is the filling of the board. If it is not good, it is easy to cause the pad to fall off, the board is deformed and bent, the thickness of the board is inconsistent, and the tolerance is too large. Class A can achieve various applications. , and b-grade can only be used for low-grade products, because a-grade materials are highly guaranteed in quality, so the plate manufacturers mark them, while b-grade and c-grade have no quality assurance, no marks, and no after-sales processing. So don't mark it, for fear of damaging the reputation of the board manufacturer. This is one of the ways to identify good and bad boards.

　　Summary: Compared with a-grade materials, b-grade and c-grade materials are cut corners, shoddy, and glass fiber cloth is not good, which directly leads to the instability of the circuit board, which leads to the instability of your electronic products. Unstable, seeing this also roughly understands why the copper foil is easy to fall off!

　　5. How to recognize that it is a grade A sheet and ensure that your circuit manufacturer does not need low-grade sheet

　　Grade A material

　　Method 1: In addition to the mark, it should be indicated in the contract that it is a grade A material, otherwise all the responsibilities caused by the plate shall be borne by the plate factory;

　　Method 2: Generally, all the A-grade materials of sheet manufacturers will be marked, such as the A-grade material in Kingboard (kb) material, the word kb in the sheet, if it is other grades like B-grade and c-grade in kb If the performance is very poor, there is no mark, so the easiest way to distinguish is to see if there is a mark on the plate (Note: the mark exists in the plate, if there is copper on it, it cannot be found, if there is no line, that is, etched areas will be displayed),

　　6. Uncover the unspoken rules of the industry

　　90% of the circuit board factories in Shenzhen use the B material and C material without performance guarantee. Except for some foreign single factories, the performance requirements are more stringent and use the A grade material! This is why foreign products, even if they are OEM in China products with stable performance, but in China's domestic products, there are always problems of one kind or another. One of the most fundamental reasons is that the materials used are a few grades worse. This is an unspoken rule of the industry. Okay, what's more, for a non-professional you, sometimes you can't tell from the book, what kind of sheets are available in the sheet warehouse, and customers don't know if they don't ask for it, so as to maximize profits. This is the most direct way. The result is that it damages the customer's right to know and damages the interests of the customer. In fact, it is not conducive to the long-term development of the circuit board industry for a long time!

　　Double-sided bonding circuit board proofing production

　　Seven, the harm of bad board

　　Defective boards are completely composed of cutting corners, or they are shoddy, and the performance is not good. It is conceivable that the harm it can bring is natural. It is also said that the most important part of electronic products is the circuit board, and The quality of the circuit board depends largely on the circuit board. If the circuit board is not good, it will bring this or that kind of harm to your electronic board. The hazards are as follows:

　　1. During welding, the pads are very easy to fall off, resulting in the destruction of the entire board;

　　2. After a period of operation of the circuit board, slight deformation occurs, and the deformation and shrinkage of the circuit board lead to unstable performance;

　　3. The material change of the board can lead to a more serious problem, deforming your circuit and leaving your circuit board in a completely unstable state;

　　4. For rework, if the board is not good, the pad will easily fall off, and the side will directly lead to the destruction of the reworked product, resulting in serious losses.

　　Shenzhen Technology Co., Ltd., as a professional PCB circuit board supplier, focuses on the production of high-precision double-sided/multi-layer circuit boards, HDI boards, thick copper boards, blind and buried via boards, high-frequency circuit boards, as well as PCB proofing and small and medium-volume boards. manufacture. We deliver faster at the same cost, and our cost is lower at the same delivery speed. At present, it has a PCB circuit board production base and a technology research and development base, and has set up service centers in many major electronic product design centers in China, and has provided rapid electronic manufacturing services to more than 2,000 customers around the world.

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