I was looking for IC packages where I can mount a small wafer (3mmx3mm) wire bond to the leads of the package and conduct operation at 500C. I have contacted couple of companies which do ceramic IC packages but they only guarantee operation till 250C. Would these ceramic packages hold till 500C? Also, is there any conductive thermal paste to mount the wafer which can sustain 500C? Any help would be very useful!
An IC usually consists of these things:
- Epoxy to encapsulate the IC
- Wire bonding (usually gold)
- Chip or Die
I would think that the concern would be with each of the materials of the package. I know that most solders start to lose their structural stability at 250C. I know that IC epoxies don't survive much after 250C either from personal experience. The wire bonds would also need to support high temperatures. All of these components need to support operation higher than 250C.
I would think that the solder would be the most limiting factor, and solders with higher melting points can be found up to 450C, after that its a different process called hard soldering or brazing.
Semiconductors become conductors above a temperature related to the band-gap. A few materials, such as pure carbon (e.g., diamond) and silicon carbide (SiC), have been used to make experimental or custom designed devices such as low power IC's and high power IC's that operate at 500°C.
As far as thermal transmission and insulation, diamond is ne plusa ultra. Since gallium wets diamond, you could make a Ga/C/Ga sandwich to conduct heat and insulate electrically. The diamond probably would be less expensive than the special-purpose IC!
Though you might be able to order (and afford!) such a device, might it be possible to move signal processing to a cooler location? Admittedly, in borehole logging and spacecraft to land on Venus, this might not be a choice, but look for a more practical alternative.