Multilayer Lamination
High-density interconnect structures require multiple bonding cycles to build up complex dielectric and conductive inner layers. Sequential press passes define the repeated application of thermal lamination cycles to bond additional prepreg layers and microvia structures onto previously cured sub-stacks. Advanced HDI designs rely on this step-by-step fabrication method.
Stackup Construction
Build-up microvia technology requires sub-assemblies to undergo complete inner-layer processing, lamination, drilling, and plating before receiving the next dielectric layer. Utilizing sequential press passes enables complex blind and buried via architectures that cannot be drilled in a single operation. Sub-stacks undergo surface preparation, resin filling, and planarization prior to subsequent prepreg lay-up and pressing.
Thermal stress accumulates within early cured layers during each additional high-temperature, high-pressure bonding cycle. Glass transition temperatures of base resins must withstand multiple thermal excursions without experiencing resin degradation or glass weave separation. Microsection analysis checks dielectric thickness uniformity and interface bond strength after each press iteration.
Thermal Degradation
Material selection for multi-press build-ups mandates high thermal stability resins capable of enduring multiple press profiles. Executing sequential press passes increases dimensional registration drift due to repeated expansion and contraction cycles. Specialized low-loss laminates retain structural integrity through consecutive lamination schedules.
Final acceptance testing inspects for internal delamination micro-cracks.
