Degradation Profile
Lamination press accessories experience repeated thermal and mechanical cycling that reduces their ability to conform to surface topographies. Over multiple pressing runs, cushion pad fatigue occurs when elastomeric matrix structures or cellulose fibres collapse permanently under sustained hydraulic force at elevated temperatures. The loss of resilience leads to uncompensated thickness variations across the multi-layer stack, leaving outer edges subjected to higher force than the center of the platen.
This defect mechanism limits the operating lifespan of reusable press pads during sequential board bonding operations. As core materials harden, the pad no longer absorbs mechanical tolerances from platen surfaces.
Pressure Distribution
Thickness gradients across a depleted pad convert uniform hydraulic clamping into localized pressure spikes and valleys during the heating ramp. When cushion pad fatigue progresses past acceptable limits, resin flow within prepreg layers becomes uneven across the panel surface. Low-pressure regions suffer from inadequate resin fill around inner-layer copper traces, forming microscopic void pockets.
High-pressure areas experience excessive resin squeeze-out.
Replacement Threshold
Thickness monitoring and durometer hardness testing track pad breakdown prior to copper foil defects. Measuring permanent set after fixed lamination cycles establishes retirement criteria for consumable press materials. Uncompensated pads cause preventable yield loss during production runs.
