Lamination is the most critical and challenging step in manufacturing copper-based PCBs.The lamination process uses high heat and pressure to bond the copper foil, insulating dielectric layer, and copper substrate firmly together. The key challenges are:
Pressure Control
Too little pressure can lead to delamination or poor thermal conductivity. Too much pressure, especially with thick copper substrates, can cause the substrate to warp or deform, and in some cases, even crush the ceramic rollers or other equipment.
Temperature Profile Control
The heating rate, curing temperature, and cooling rate must all be precisely controlled. Uneven temperatures or an improper temperature profile can result in the dielectric layer being under-cured (affecting thermal conductivity and bonding strength) or over-cured (making it brittle and prone to cracking).
Void and Delamination Risks
Copper, the insulating adhesive, and copper foil have vastly different coefficients of thermal expansion (CTE). During lamination, if gases are not properly vented or if pressure is uneven, tiny bubbles or voids can easily form. These defects severely hinder heat transfer and are a primary cause of product failure.
Copper Substrate Flatness
If a thick copper substrate itself isn't perfectly flat, it's extremely difficult to ensure a uniform thickness of the insulating layer during lamination. This compromises the overall thermal uniformity and reliability of the finished product.
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