Analytical Models for Viscous Squeeze Flow Trace Swim in Multilayer Buildups
Analytical squeeze flow models predict trace swim by calculating hydrodynamic drag and side-wall pressure differentials across fine copper features during lamination.
Matrix Cross Linking
Polymer Network
Chemical binding of polymer chains during the curing process transforms liquid resin into a solid, heat-resistant board substrate. The density of this matrix cross linking determines the mechanical strength and dimensional stability of the finished circuit board. This molecular structure holds the glass fibers in place and prevents layer separation.
A fully cured polymer network is essential for withstanding the thermal shock of solder reflow.
Thermal Property
Thermal stability of the board laminate is directly related to the density of the internal chemical bonds. As matrix cross linking increases, the glass transition temperature of the substrate rises, enabling the board to maintain its stiffness at higher temperatures. Incomplete curing makes the material soft and prone to warp during soldering.
This physical property is checked using thermal analysis tools.
Chemical Resistance
Interlocking of the resin molecules increases the resistance of the laminate to moisture ingress and chemical breakdown. If the matrix cross linking is insufficient, the board remains susceptible to delamination under the intense heat of lead-free assembly. Solvents used in board cleaning can penetrate weak polymer chains and swell the substrate.
Testing the cure level of the resin using differential scanning calorimetry ensures the structural integrity of the circuit board before it undergoes automated drilling. Achieving the correct molecular cure avoids crack formation along drilled holes.