Printed circuit board (PCB) commonly places a layer of copper foil on glass epoxy substrate. The copper foil thickness is usually 18μm, 35μm, 55μm and 70μm. Most used thickness of copper foil is 35μm. On this basis, circuit width is 1mm. The resistance value is about 5mΩ and inductance is 4nH. When di/dt of digital IC chip on the PCB is 6mA/ns, and working current is 30mA, the estimated noise voltage respectively is 0.15mV and 24mV on basis of every 10mm circuit containing resistance and inductance values.
The main purpose of heavy copper is to ensure enough copper coating in the holes and resistance in the proper range. In terms of dip components, it can fix in right place and ensure connection strength. In terms of surface mount components, some vias are only through holes with function of conductivity of both sides. We strive to be your top choice of PCB manufacturer.
Inspection items of heavy copper PCB manufacturing
1. Check via metallization quality status to ensure there are no remains, burrs, black vias ect.
2. Check if substrate surface contains dirt and other remains.
3. Check P/N, figure number, document and proess description of substrate.
4. Figure out the loading area and requirements of coating.
5. Plating area and process parameters should be clear to ensure the stability and viability of copperplating process.
6. Clean and preparation of conductive parts, solution activated through conductivity.
7. Check if solution composition is qualified and plate surface area.
8. check the contact parts of the firm, the voltage and current range.
Quality control of heavy copper PCB manufacturing
1. A precise calculation of current effects of coating area during production process. To determine the correct current value and control current changes to ensure process parameters stable.
2. Prior to copperplating, try to use debug board plating and make solution activated.
3. Determine the direction of current flow, and board’s order commonly from far to near position. Ensure uniformity of current on any surface.
4. Ensure vias uniformity of coating thickness and coating consistency, except mixing filter measures, the surge current should be used.
5. Regularly monitor current changes during copperplating to ensure the current value reliability and stability.
6. Inspect via copper thickness meets technical requirements.