Selecting Tooling Shields for Thermal Protection during Selective Soldering Cycles
Selecting selective soldering tooling shields requires matching composite thermal resistivity against component clearance gaps to guarantee zero thermal damage.
Spring Buttons
Contact Terminal
Surface mount interconnects often utilize compressible conductive elements to provide temporary or modular electrical paths between two parallel circuit boards. These spring buttons consist of a plunger and a spring mechanism housed within a small metal shell that is soldered to the PCB. They allow for easy assembly and disassembly of sub-modules without the need for permanent connectors or wiring harnesses.
Mechanical Compliance
Compression of the internal spring ensures a consistent contact force against the mating pad even when there are variations in the gap between the boards. This force must be high enough to break through surface oxides but low enough to avoid damaging the plating on the target. Because spring buttons rely on mechanical pressure, the plating on both the plunger and the pad is usually hard gold to minimize wear over many cycles.
The current-carrying capacity of the interface is limited by the cross-sectional area of the spring and the contact resistance at the plunger tip. Designers must account for the height of the component when compressed to avoid bottoming out the spring, which could lead to mechanical failure. These parts are frequently used in battery charging docks and modular handheld devices.
Signal Integrity
Inductance of the coiled spring inside the housing can degrade high-speed signals by introducing impedance mismatches. If the operating frequency is high, the parasitic effects of the spring buttons must be modeled to ensure the data path remains stable.