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One: hole copper.
Hole copper is a very critical quality indicator! Because the conduction of each layer of the board depends on the copper hole, and the copper hole needs to be electroplated with copper. This process takes a long time and the production cost is high. Therefore, in the environment of low price competition, some factories have begun to cut corners., Shorten the copper plating time. Especially in some allegro factories, in recent years, many allegro factories in the industry have begun to apply a "conductive glue process". The advantages of this process are: fast speed, low cost, and an average cost saving of 20-30 yuan per square meter. However, it There is a fatal flaw, that is, the thickness of the copper plating 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 hole copper. If it is used in consumer products, it can meet the needs, but if your product has requirements for quality, it must be energized for a long time, under vibration, and under conditions. careful!
Two: Plate.
In the fixed cost of PCB board accounts for nearly 30%-40% of the cost. It is conceivable that many board factories will cut corners in the use of boards in order to save costs. Everyone knows that the sheet material we use, scientific name: FR-4, is a glass epoxy resin. The difference between a good board and a bad board is as follows:
1. Fire rating. There is a secret in our industry that is not open to the public. Many board factories are using non-flame retardant sheets. This ratio is huge! If you tell me the price of the 2-layer board you bought is less than 300 yuan/square, then I tell you, please take out the lighter and take a look! Non-flame retardant sheets can be ignited. If non-flame retardant sheets are used in your products, the consequences will be risky. Evaluate this yourself!
2. Fiber layer. Qualified panels are normally made by pressing at least 5 glass fiber cloths. This determines the breakdown voltage and fire tracking index of the board.
3. The purity of the resin. Poor sheet material has a lot of dust. It can be seen that the resin is not pure enough. This kind of sheet is very dangerous in the application of multi-layer boards, because the holes of the multi-layer board are very small and dense!
Three: pressing.
To see if a board factory has the strength, it is not professional to do multi-layer boards, you only need to ask one question: Do you have your own laminating machine?
At present, many small factories in the market are outsourcing the pressing, why? First of all, the pressing equipment is expensive and the cost is high. Secondly, if it is not a professional multi-layer board manufacturer, they generally choose to externally press.
For multilayer boards, pressing is a very important process! Whether it is the pressing equipment, technology, management, and personnel experience, all determine the quality of the pressing! If the pressing is not done well, it will seriously affect 3 points:
1. The board-layer bonding is not good and it is easy to delaminate.
2. Impedance value. PP is in a state of glue flow under high temperature pressing, and the thickness of the final product will affect the error of the impedance value.
3. Yield rate of finished products. For some high-layer PCB boards, if the distance from the hole to the inner layer line and the copper skin is only 8 mils or even less, then the bonding level must be seriously tested. If the stack is offset during pressing, the inner layer is off-position, and after the hole is drilled, there will be a lot of open circuits in the inner layer.
