What Is the Manufacturing Process of PCB Entry Sheets
The production process of different aluminum drilling entry sheet manufacturers is similar, but the quality may vary a lot because of the different controls in the special processing craft.
The basic production flow of aluminum PCB sheet is cutting-drilling-optical imaging-QC-etching-solder resist ink-character-QC-hot air leveling-aluminum surface treatment-shape-final inspection-packaging-delivery.
1. Cutting. PCB entry sheets have strict requirements on the appearance of aluminum surfaces (scratches, pinholes, stains, etc.). When purchasing raw materials, aluminum PCB sheet manufacturers recommend purchasing aluminum sheet with protective films on aluminum surfaces.
2. Drilling. The aperture tolerance of the aluminum sheet is strict, and the size of the drill bit should be measured before drilling. The aluminum base plate with copper thickness greater than or equal to 3 ounces should be carefully controlled to control the occurrence of burrs.
3. Optical imaging. The surface treatment of aluminum-based circuit board only brushes the copper surface. The aluminum base surface has a protective film, and the film is only attached to the copper foil surface.
4. Etching. Before etching, make sure that the protective film of the aluminum base plate is not damaged. Both acid etching and alkaline etching solutions can be used. After etching, it is strictly forbidden to scrape the lines of the aluminum substrate with a knife to avoid hurting the insulating medium layer, causing sparks and leakage during the voltage test.
5. Solder resist ink. The aluminum PCB sheet manufacturers usually adopt liquid photoimageable solder resist ink. The process is: board brushing(copper only)-solder resist ink printing (first time)-baking -solder resist ink printing (second time)-baking-exposure-development-curing-characters printing. It should be ensured that the thickness of the solder mask on the circuit and the corner should be 10 microns,thus getting a uniform and beautiful appearance.
6. Hot air leveling. Before hot air leveling, the board should be baked first. If the protective film on the surface of the aluminum substrate is not resistant to high temperature, the protective film needs to be torn off.
7. Aluminum base surface treatment.Some customers require a protective film to protect the aluminum substrate during delivery. At this time, the protective film should be attached. If not, the aluminum surface should be passivated once to form a thin, colorless and transparent protective film on the surface of the aluminum PCB sheet.
Original source: https://www.hm-alu.com/a/what-is-the-manufacturing-process-of-pcb-entry-sheets.html
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