Although many customers and friends have been deeply involved in the electronic industry for many years, as the saying goes: there are specialties in the technical field! Perhaps you are not sure about the real quality of PCB. Xiaobian has been working in the PCB industry for ten years. Today, I will simply talk to my friends: the three elements that really determine the quality of PCB!
One: hole copper.
Copper is a key quality index! Because the conduction of the circuit of each layer of the board all depends on the hole copper, and this hole copper needs to be electroplated with copper. This process takes a long time, and the production cost is very high. Therefore, in the environment of low-price competition, some factories start to cut corners and shorten the copper plating time. Especially in some allegro factories, many allegro factories in the industry began to apply a “conductive adhesive process” in recent years. The advantages of this process are: high speed and low cost, and the average cost per square meter can be saved by 20-30 yuan. However, it has a fatal defect, that is, the copper plating thickness is not enough.
This can be said to be a secret in the industry, and few people outside the PCB industry know this. The board made by the conductive adhesive process has thin and uneven copper holes, which can meet the needs if it is used in consumer products. However, if your products have quality requirements, you must be careful if it is electrified and vibrated for a long time!
Two: Plate.
In the fixed cost of PCB, the board accounts for nearly 30%-40% of the cost. It can be imagined that many board factories will cut corners in the use of boards in order to save costs. As we all know, the sheet metal we use, scientific name: FR-4, is a kind of glass epoxy resin. There are the following differences between good plates and bad plates:
1. Fire rating. Here’s an undisclosed secret in our industry. Many board factories are using non-flame retardant sheets. This ratio is very large! If you tell me that the price of the 2-layer board you bought is below 300 yuan/Ping, then I’ll tell you, please take out your lighter and check it! Non-flame retardant sheet metal can be ignited. If non-flame retardant sheet metal is used in your products, the consequences will be risky. Evaluate this yourself!
2. Fiber layer. The qualified sheet is usually made by pressing at least 5 pieces of glass fiber cloth. This determines the breakdown voltage and fire-proof mark index of the board.
3. Purity of resin. There is a lot of dust in the poor sheet metal, as can be seen, the resin is not pure enough, and this kind of sheet metal is very dangerous in the application of multilayer board, because the holes of multilayer board are particularly small and dense!
Three: pressing.
To see if a board factory has the strength and is specialized in making multilayer boards, you only need to ask one question: Do you have your own laminating machine?
At present, the stitching of many small factories in the market is outsourced. Why? First of all, the pressing equipment is expensive and the cost is high. Secondly, if it is not a professional manufacturer of multi-layer boards, they generally choose external pressing.
For multilayer boards, pressing is a very important process! No matter the equipment, technology, management and personnel experience, it determines the quality of pressing! If the pressing is not done well, it will seriously affect three points:
1. The combination of the laminates is not good, and it is easy to be layered.
2. Impedance value. PP is in a flowing state under high temperature pressing, and the thickness of the final product will affect the error of impedance value.
3. The yield of finished products. For some high PCB boards, if the distance from the hole to the inner wire and copper skin is only 8mil or even smaller, it is necessary to seriously test the pressure level. If the lamination is offset, the inner layer is offset, and the hole is drilled, many inner layers will be open.
For PCB, the appearance, V-cut, surface treatment, etc. are not the most critical issues. These are manageable and salvageable quality hazards, but the above three points are the three most critical hard tests for a PCB. Dear little brothers and sisters, you must choose a good PCB manufacturer when buying a board!