Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Epoxy Cracked & Capacitor Cracked

Simon Ting

#14393

Epoxy Cracked & Capacitor Cracked | 9 September, 1998

hi, 1206 capacitor with silver/palladium termination is mounted onto a ceramics substrates. Bonding is achieved through conductive epoxy. We discovered that the epoxy cracked and this caused missing capacitor. We had tried different grade of epoxy, curing profile, curing time, curing temperature and still unsuccessful. In additional, we are also facing with cracked/broken capacitor. Usually, defects appeared as line cracked, discolourisation cracked, chipped corners, chipped body and the defects occurred randomly. We had improved the pick & place head (ie. change to softer material, less gripping force, placement force)and yet we are still seeing the problems. Is it because the capacitor is mounted on ceramics substrate that is giving us the problem? Warm regards, simon ting

reply »

Earl Moon

#14394

Re: Epoxy Cracked & Capacitor Cracked | 10 September, 1998

| hi, | 1206 capacitor with silver/palladium termination is mounted onto a ceramics substrates. Bonding is achieved through conductive epoxy. | We discovered that the epoxy cracked and this caused missing capacitor. We had tried different grade of epoxy, curing profile, curing time, curing temperature and still unsuccessful. | In additional, we are also facing with cracked/broken capacitor. Usually, defects appeared as line cracked, discolourisation cracked, chipped corners, chipped body and the defects occurred randomly. We had improved the pick & place head (ie. change to softer material, less gripping force, placement force)and yet we are still seeing the problems. Is it because the capacitor is mounted on ceramics substrate that is giving us the problem? | Warm regards, | simon ting The TCE of epoxy (15-17 ppm/degree C.) is far greater than either the ceramic substrate or device (5-7 ppm/degree C.). This may cause problems under thermal stress conditions as operation under current or high heat conditions. Earl Moon

reply »

soldering station

Reflow Ovens thermal process improvement