Patent ID: 6678949
Filing Date: 2004-01-20
Classification: H01L,H05K,Y02P,Y10T

Abstract:
In a process for forming a structure upon which electronic devices can be mounted, in which process a multi-layer thin film is built and carried on a first sacrificial carrier and a multi-level ceramic substrate is patterned with lines, vias, and an array of contacts, the improvement comprising the steps of:forming solder bumps on the contacts of the multi-level ceramic substrate; securing a second sacrificial carrier to the thin film on a surface opposite the first sacrificial carrier; removing the first sacrificial carrier to expose the surface of the thin film to be secured to the multi-level ceramic substrate, the second sacrificial carrier being rigid and without through openings to prevent distortion of the multi-level ceramic substrate; forming solder bumps on conductive contacts on the exposed surface of the thin film, the solder bumps arranged on the thin film in an array corresponding to the array of solder bumps on the substrate; positioning the solder bumps of the thin film opposite to and in alignment with the solder bumps of the substrate; applying heat of less than about 400Â° C. and inward pressure less than 200 psi to the solder bumps in a closed solder joint process thereby causing opposite pairs of the solder bumps to form solder connections between the thin film and the substrate; removing the second sacrificial carrier after forming solder connections, whereby the thin film is bonded and electrically connected to the multi-level ceramic substrate to form a structure suitable for electronic devices.