We have developed active and passive devices embedded multilayer board utilizing our laminate-based WLCSP embedding technology. The proposed embedded board is realized by laminating plural circuit formed polyimide films together by adhesive with thin devices being arranged in between those polyimide layers. The electrical connection via has a filled via structure composed of the alloy forming conductive paste which ensures high reliable connection. The embedded active device is WLCSP which has no solder bump on its pads therefore the thickness of the die is reduced to 80 microns. The embedded passive device is a chip resistor or capacitor whose thickness is 150 microns with copper electrodes. The electrical connection between components and board's circuits are made by same conductive paste vias. The thin film based structure and low profile devices yields the 260 microns thickness board which is the thinnest embedded of its kind in the world. To confirm the reliability of the embedded board, we have performed several reliability tests on the WLCSP and resistors embedded TEG board of 4 polyimide/5 copper circuit layers. As environmental tests, we performed a moisture reflow test compliant to JEDEC MSL2 followed by a thermal cycling test (−55 deg.C to 125 deg.C, 1000cycles) and a high temperature storage test (150 deg.C). All tested samples passed the moisture reflow test and showed no significant change of circuit resistance after the thermal cycling/high temperature storage tests. Moreover, mechanical durability of the board was also confirmed by bending the devices embedded portion. The embedded device was never broken and the circuit resistance change was also within acceptable range. The proposed embedded board will open up a new field of device packaging.
Alan/Rey ok move from Flip Chip and Wafer Level Packaging 1-3-12.
Lifetime of power electronics interconnections in accelerated test conditions: High temperature storage and thermal cycling
