Ground Allocation of Multi Tier Hardware Warranty Liabilities
Ground allocation distributes warranty liability across hardware tiers based on integration depth, physical root cause, and explicit contract caps.
Surface Mount Reflow Distortion
Meaning
Mechanical warping of components or circuit boards that occurs during the high temperature phase of the soldering process. Surface mount reflow distortion is caused by the different rates of thermal expansion between plastics, metals and laminates. This movement can lead to open joints or cracked components if not controlled.
Stress Gradient
Temperature differences across the board cause some areas to expand faster than others. As the solder melts and then solidifies, these stresses can pull components out of alignment. Large connectors are particularly prone to this effect because their long bodies amplify the total amount of expansion.
Engineers use support fixtures or altered board layouts to minimize these internal forces during the heating cycle.
Material Selection
High temperature plastics are used in connectors to minimize the amount of surface mount reflow distortion. These materials have a higher glass transition temperature, which helps them remain rigid during the reflow oven cycle. Substrates with low expansion coefficients also help maintain the flatness of the assembly.
Assembly Yield
Coplanarity errors happen when a component warps so much that its pins no longer touch the solder paste. This results in a failed board that must be reworked or scrapped. Adjusting the oven profile to slow down the heating and cooling can reduce the severity of these distortions.