1. Explanation of terms:military-grade A-grade sheet: 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 base material of the sheet, and the impedance stability of the sheet , far higher than B-grade and C-grade materials in similar products, it can be used to produce military electronic products with absolutely demanding requirements!
Low-grade board B-grade materials and C-grade materials: board manufacturers, because of the low-cost demand of PCB circuit board manufacturers, thus produce boards, such boards, board manufacturers shoddy and cut corners in the manufacturing process The situation! In terms of performance stability, it is far inferior to military-grade A-grade materials, and the price is far lower than A-grade materials.
二. Classification of board grades by general board manufacturers:
Grade A: The best grade plate, meeting the requirements of military industry and industrial requirements, with quality assurance;
Grade B: Low-grade boards are used for low-grade civilian use without quality assurance;
Grade C: The lower grade is entirely for cost, and there is no quality assurance.
三. Composition of FR-4 (PCB circuit board) board
1. Glass fiber cloth;
2. Resin;
3. Copper foil.
四. Material comparison of different grades of boards and the hazards of low-grade boards:
Fiberglass cloth
copper foil
resin
Sheet application
Whether there is a manufacturer's mark
Grade A material - generally used for glass fiber cloth
Copper quality copper foil thickness is not
Grade A material 6-8 layers, with a fine whole
excellent
industrial use. military
marked
will shrink
Fiberglass cloth
Grade B material - generally used for glass fiber cloth
About 2 layers, use ordinary glass copper - generally, the thickness of copper foil
Quality stability requirements are not high
Grade B material
- general
none
Fiber cloth, and the presence of glass fiber cloth will be more
civilian
patchwork rags
Grade C material - generally used for glass fiber cloth
About 2 layers (other parts are of poor copper quality, and the thickness of copper foil will increase
Grade C material
Difference
basically unusable
none
as a filling, or with coarse roast
Relatively
made of multiple glass fibers)
Because there is less glass fiber cloth, the glass fiber cloth is not good, which leads to
To put it bluntly, copper foil is you
1) Glass fiber cloth is not good for pad capacity
Because grade A materials are of high quality and guaranteed,
The line, B-grade material and so on
Easy to fall off, 2) the plate is easy
Resin is the fill of the sheet, if
Therefore, the plate manufacturer marks it, and the grade b and grade
The next lower grade c material, use
Class A can meet various application
bending, fiberglass less, pull
Not good, it is easy to cause the pad to fall off, and grade B can only be used for
There is no quality guarantee for grades, and there is no printing
Hazardous manifestation
Inferior copper foil, which leads to
If the strength is not enough, the plate bends,
Plate deformation and bending, plate thickness
Note, do not accept after-sales treatment, so do not call
The thickness of the copper foil is inconsistent, inconsistent, and the tolerance is too large
Low-grade products
Plus fiberglass cloth is not good
mark, in order not to damage the reputation of the plate manufacturer
and conductivity are inconsistent.
words, it is very easy to cause electronic
This is one of the ways to identify good and bad plates-
And the pad is easy to fall off
Product instability, line
In a state of detachment!
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, and the instability of the circuit board leads to the failure of your electronic products. Unstable, seeing this also roughly understands why the copper foil is easy to fall off!
五. How to recognize that it is A-grade sheet and ensure that your circuit manufacturer does not use low-grade A-grade sheet
Method 1: In addition to the mark, it is also necessary to indicate in the contract that it is a grade A material, otherwise all responsibilities caused by the plate shall be borne by the plate factory;
Method 2: Generally, all board manufacturers will mark A-grade materials, such as Kingboard (kb) A-grade materials, the board has the word kb, if it is other grades, it is like B-grade and c-grade in kb If the performance is poor, there is no mark, so the easiest way to distinguish is to see if there is a mark in the board (Note: the mark exists in the board, if there is copper on it, you can’t find it, if there is no line, that is Etched areas will be displayed)
六. Uncover the unspoken rules of the industry
The hidden rules of 90% of the circuit board factories in Shenzhen are to use B materials and C materials without performance guarantee. Except for some foreign single factories, the performance requirements are relatively strict and A-grade materials are used! This is why foreign products, even if they are manufactured in China The performance of high-quality products is stable, while domestic products in China always have problems of one kind or another. The most fundamental reason is that the materials used are several grades worse. This is an unspoken rule in the industry. Well, besides, as a non-professional you, sometimes you can’t tell that there are all kinds of sheets in the sheet warehouse. If customers don’t ask for it, they don’t know it, so as to maximize profits. This is the most direct way The result is that the customer's right to know is damaged, and the customer's interests are damaged. In fact, if this continues for a long time, it is not conducive to the long-term development of the circuit board industry!
七. The hazards of bad plates
Defective boards are completely composed of jerry-built materials, or shoddy, poor performance can be imagined, and the harm it can bring is also a matter of course. I have also said that the most important part of electronic products is the circuit board, and The quality of the circuit board mostly depends on the circuit board material. If the circuit board material is not good, it will bring one or another harm to your electronic board material. The hazard performance:
1. During soldering, the pads are very easy to fall off, resulting in the destruction of the entire board;
2. After a period of operation, the circuit board undergoes slight deformation and deformation, and the deformation and shrinkage of the circuit board lead to unstable performance;
3. The material change of the board will cause a more serious problem, which will deform your circuit and make your circuit board in a completely unstable state;
4. For rework, if the plate is not good, the pads are easy to fall off, and the side will directly lead to the destruction of the reworked product, resulting in serious losses.
Senyan Circuit has 20 years of experience in circuit board industry production, specializing in the production of aluminum substrate immersion gold board PCB circuit board FPC flexible circuit board multi-layer blind buried hole board, single-sided and double-sided circuit board; multi-layer circuit board resin plug hole board, impedance circuit board, HDI circuit board, high frequency circuit board, thick copper circuit board
