profiling is advised for accurate characterization of circuit heat absorption and maximum temperature conditions. Use of PCB mounted multiple thermocouple M.O.L.E. Many reflow process profiles have peaks ranging from 240☌ to 260☌ and while ceramic capcitors and inductors can withstand soldering temperatures in this range for short durations they should be minimized or avoided whenver possible. A maximum peak reflow temperature of 225☌ should be adequate in most circumstances. Based on these facts a minimum peak reflow temperature of 205☌ to 210☌ should be established. Activation of rosin fluxes occurs at about 200☌. Solders typically utilized in SMT have melting points between 179☌ and 188☌. The circuit assembly should be preheated as shown in the recommended profiles at a rate of 1.0 to 2.0☌ per second to within 65 to 100☌ of the maximum soldering temperature. Proper preheating is essential to prevent thermal shock cracking of the capacitor. Never contact the ceramic surface with the iron tip.Preheat circuit and ceramic component to 150☌.In the event that a soldering iron must be employed the following precautions are recommended. Wave soldering is discouraged.Ĭeramic capacitor attachment with a soldering iron is discouraged due to the inherent limitations on precisely controlling soldering temperature, heat transfer rate, and time. Due to the unique internal construction of the LASERtrim® it is recommeded that a convervative reflow temperature profile be used (Fig.4). LASERtrim® Capacitors - Offered with gold flashed nickel- barrier terminations only. High Frequency Ceramic Capacitors & Inductors – Offered with standard tin plated nickel-barrier terminations compatible with solder flow and reflow process. For this reason it is reccommened that the assembly qualification process employ suitable testingto expose the presence of micro-cracking conditions.Ĭeramic components’ leads composition and soldering compatibility It should be noted that micro-cracks in ceramic can be difficult to detect with normal post assembly visual and electrical testing and can pose a significant threat to reliable field operation. Due to ceramic capacitor’s crystalline micro-structure these components are susceptible when exposed to excessive thermal or mechnical shock during circuit processing. Ceramic chip capacitors exhibit excellent reliability characteristic sproviding that proper circuit design techniques and controlled assembly processes are utilized.
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