Technical requirements for aluminum base board
The main technical requirements are:
Size requirements: including board size and deviation, thickness and deviation, verticality and warping degree;
Appearance: including crack, scratch, burr and layering, aluminum oxide film and other requirements;
Performance: including peel strength, surface resistivity, minimum breakdown voltage, dielectric constant, flammability and thermal resistance requirements.
Special detection method for aluminum based copper clad plate:
1. The measurement method of dielectric constant and dielectric loss factor is series resonance method with variable Q value. The principle of connecting the sample and the tuning capacitor in series to the high-frequency circuit to measure the Q value of the series circuit;
2.The heat resistance measurement method is calculated by the ratio of temperature difference between different temperature measuring points and thermal conductivity.
Second, aluminum base board line production
(1) mechanical processing:
Aluminum base board drilling can be, but after drilling hole inside the hole edge is not allowed to have any burr, which will affect the pressure test. Shape milling is very difficult. And punching shape, need to use advanced mold, mold production is very skilled, as one of the difficulties of aluminum base board.
After punching the appearance, the edges should be very neat, without any burrs, and do not touch the welding resistance layer at the edge of the plate. Usually using the operation mode, hole from the line, shape from the aluminum surface, the circuit board when the force is cut down, and so on are skills. After punching appearance, the board warping degree should be less than 0.5%.
(2) aluminum base board surfaces shall not be scratched in the whole production process:
It is absolutely unacceptable for the surface of aluminum base board to change color and turn black after being touched by hand or by some chemicals, and some customers do not accept it when they re-polish the aluminum base board. Therefore, it is one of the difficulties in the production of aluminum base board that the whole process does not touch or break the aluminum base board.
Some enterprises use passivation process, some in hot air leveling (spray tin) before and after each affixed with protective film......A lot of tips, eight immortals across the sea, each show his own tricks.
(3) over-high pressure test:
Communication power supply aluminum base board requires 100% high voltage test, some customers require direct current, some require alternating current, voltage requirements of 1500V, 1600V, the time is 5 seconds, 10 seconds, 100% PCB for testing.
Dirt on the board, holes and aluminum base board edge burrs, serrated lines, any touch of insulation can lead to high voltage test fire, electricity leakage, breakdown. Pressure test board layer, bubble, are rejected.
Iii. Production specifications of aluminum PCB
1. Aluminum base board is often used in power devices, power density, so the copper foil is relatively thick.If more than 3oz copper foil is used, the etching process of thick copper foil needs to be compensated by the line width of engineering design, otherwise, the line width after etching will be out of tolerance.
2. The aluminum base board must be protected with protective film in advance during PCB processing, otherwise, some chemicals will erode the aluminum base board, resulting in damage to the appearance. And the protective film is easily damaged, resulting in a gap, which requires the whole PCB processing process must be socket.
3. The hardness of the milling cutter used for fiberglass board is relatively small, while the hardness of the milling cutter used for aluminum base board is large. In the process of manufacturing glass fiber board milling cutter speed is fast, and the production of aluminum base board is at least two-thirds slower.
4. Computer milling side glass fiber board just use the heat dissipation system of the machine itself can be heat dissipation, but processing aluminum base board must be in addition to the gum-head plus alcohol heat dissipation.
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Post time: Aug-31-2019