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Protecting Neighboring Devices from Heat Damage During PCB Rework
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Effective Shielding of Nearby Components in PCB Rework Bob Wettermann, MIT
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Transcript of Protecting Neighboring Devices from Heat Damage During PCB Rework
Effective Shielding of Nearby Components in PCB Rework
Bob Wettermann, MIT
• Shielding Alternatives• Experimental Method• Results• Conclusions
Outline
Heat Sensitive ComponentsAluminum and tantalum ceramic capacitors, crystals, oscillators, plastic-bodied components such as connectors
Battery Destruction
IMC Growth Impact Reliability
Conduction
Convection
Radiation
Radiant Heat
Possible Materials for Heat Shielding
Thermal ConductivityMaterial Thermal Conductivity(Watts/m K @ 330°C)
Kapton Type MT 0.37304 Stainless 18Copper 379Ceramic Fiber 0.14Clay/Water Gel Unknown
Experimental Method
Materials Used•Stainless steel 304•1650 Venture tape-copper with tape backing•Ceramic non-woven fiber•3mil thick Kapton™•“Cold Shield” clay gel
Clay Gel
Experimental Method
Experimental Method
Experimental Method
Experimental Method
Experimental Method
Experimental Method
Experimental Method
Experimental Method
Experimental Method
ResultsDistance from test IC Speaker
30.95mmBattery
9.73mmConnector
6.14mm Rework Location
Control (no shields) 123° C 227° C 173° C 232° C
Copper Tape 106° C 129° C 128° C 232° C
Stainless Steel 61° C 158° C 143° C 239° C
Clay/Water Gel 66° C 89° C 86° C 231° C
Kapton™ Tape 99° C 145° C 153° C 241° C
Ceramic Fiber 63° C 111° C 113° C 231° C
• Clay/water gel best performer (needs further testing for impact)
• Ceramic fiber material best known tested material
• Kapton™ tape worst performing
Conclusion
Effective Shielding of Nearby Components in PCB Rework
Bob Wettermann, MIT
www.solder.net
