Illumination Aluminum PCB With Thick Copper 3oz
For aluminum clad pcb with thick copper of 3oz, the following difficulties will be encountered in manufacturing:
1. Compensation of engineering design line width: due to copper too thick, the line width must be compensated, otherwise the line width is out of tolerance after etching, which is not accepted by customer, and the compensation value of line width must be accumulated.
2. Uniformity of printing pcb solder mask: due to the extraordinary thick of copper for the circuit after etching, printing solder mask is very difficult, and customers will not bear overthickness and overthinfness.How to print this green oil well is also one of the difficulties.
3. Etching: it is must that the line width meet customer's drawings after etching. Copper residues are not allowed and cannot be scraped by a knife, which will scratch insulation layer and cause spark and leakage in the withstand voltage test.
4. Machining: the aluminum clad pcb can still be drilled, but no burr is allowed for the inner hole edge of the drilled hole, which will affect withstand voltage test. Milling the outline is very difficult. While for punching outline, we need to use high-grade mold.After outline is punched, the edges request very neat, without any burr, and can not touch solder mask layer. Generally we use operating mold, punching holes when make circuits, and punching outline from aluminum pcb surface. After punching finished, the warping degree of the pcb should be less than 0.5%.
5. The whole production process is not allowed to scratch the aluminum surface: if aluminum surface is touched by hand or a certain chemical,all will change the aluminum color or to be black on the appearance, which is definitely not acceptable.So no touching or damaging aluminum surface during the whole production process is one of the difficulties.
Some factories choose passivation technology, some paste protective film before and after hot air leveling (spray tin)...There are a lot of tips.
6. High-voltage test: 100% high-voltage test is required for communication power aluminum clad pcbs. Some customers require direct current, while others require alternating current, voltage needs 1500V or 1600V and time is 5S or 10s,electric test rate is 100%.
Dirty appearence, hole and edge burrs on the board,circurt serrations, and any small damage to insulation layer can result in firing,electrical leakage and breakdown during high voltage test.The PCBs will be rejected if stratified or foaming for withstand voltage test.