Air cavity package using high temperature silicone adhesive
An air cavity package includes a dielectric frame that is formed from an alumina ceramic, a polyimide, or a semi-crystalline thermoplastic. The dielectric frame is joined to a flange using a high temperature silicone adhesive. Leads may be bonded to the dielectric frame using a high temperature organic adhesive, a direct bond, or by brazing.
1. An air cavity package adapted to contain a die, comprising:
a flange having an upper surface; and
a dielectric frame having an upper surface and a lower surface, the lower surface being attached to the upper surface of the flange;
wherein the dielectric frame is made of an alumina ceramic, a polyimide, or a semi-crystalline thermoplastic, and the dielectric frame is attached to the upper surface of the flange via a high temperature silicone adhesive capable of withstanding an excursion of 320° C. for 5 minutes.
2. The air cavity package of claim 1 , further comprising a first conductive lead and a second conductive lead, attached to opposite sides of the upper surface of the dielectric frame.
3. The air cavity package of claim 2 , wherein the first conductive lead and the second conductive lead are attached to the upper surface of the dielectric frame by a high temperature silicone adhesive an excursion of 320° C. for 5 minutes.
4. The air cavity package of claim 3 , wherein the high temperature silicone adhesive is a pure silicone or a polydimethylsiloxane filled with about 20 volume percent or less of silica particles.
5. The air cavity package of claim 2 , wherein the first conductive lead and the second conductive lead are made of copper, nickel, a copper alloy, a nickel-cobalt ferrous alloy, or an iron-nickel alloy.
6. The air cavity package of claim 2 , wherein the first conductive lead and the second conductive lead are attached to the upper surface of the dielectric frame by a direct bond, a braze, a high temperature reactive solder, or a high temperature adhesive.
7. The air cavity package of claim 1 , wherein the flange is made of copper, a copper alloy, aluminum, an aluminum alloy, AlSiC, AlSi, Al/diamond, Al/graphite, Cu/diamond, Cu/graphite, Ag/diamond, CuW, CuMo, Cu:Mo:Cu, Cu:CuMo:Cu (CPC), Mo, W, metallized BeO, metallized Si3N4, or metallized AlN.
8. The air cavity package of claim 1 , wherein the flange is a substrate plated with one or more metal sublayers.
9. The air cavity package of claim 8 , wherein the one or more metal sublayers are made of nickel (Ni), gold (Au), palladium (Pd), chromium (Cr), or silver (Ag).
10. The air cavity package of claim 1 , wherein the high temperature silicone adhesive is a polydimethylsiloxane filled with greater than zero to about 20 volume percent of silica particles.
11. The air cavity package of claim 1 , wherein the dielectric frame further comprises a filler, wherein the filler is selected from the group consisting of ceramic powder, glass powder, and chopped glass fibers.
12. The air cavity package of claim 1 , wherein the dielectric frame has a dielectric constant of about 3.0 to about 10.0.
13. An air cavity package adapted to contain a die, comprising:
a flange having an upper surface; and
a dielectric frame having an upper surface and a lower surface,
wherein the lower surface is attached to the upper surface of the flange via a high temperature silicone adhesive capable of withstanding an excursion of 320° C. for 5 minutes; and
wherein the high temperature silicone adhesive is a polydimethylsiloxane filled with greater than zero to about 20 volume percent of silica particles.
14. An air cavity package adapted to contain a die, comprising:
a CuW flange having an upper surface;
a ceramic dielectric frame having an upper surface and a lower surface, the lower surface being attached to the upper surface of the flange via a high temperature silicone adhesive capable of withstanding an excursion of 320° C. for 5 minutes; and
a first conductive lead and a second conductive lead, attached to opposite sides of the upper surface of the dielectric frame and each being attached to the upper surface of the dielectric frame by a direct bond.
15. A method for forming an air cavity package, comprising:
joining a lower surface of a dielectric frame to an upper surface of a flange using a first adhesive composition comprising a high temperature silicone adhesive which can withstand an excursion of 320° C. for 5 minutes;
joining a first conductive lead and a second lead to an upper surface of the dielectric frame using a second adhesive composition; and
curing the first adhesive composition and the second adhesive composition, either separately or simultaneously;
wherein the dielectric frame comprises an alumina ceramic or a polyimide.
16. The method of claim 15 , wherein the second adhesive composition is a high temperature silicone adhesive which can withstand an excursion of 320° C. for 5 minutes.
17. The method of claim 16 , wherein the high temperature silicone adhesive is a pure silicone or a polydimethylsiloxane filled with about 20 volume percent or less of silica particles.
18. The method of claim 15 , wherein the curing is performed at a temperature of about 160° C. to about 220° C. and a pressure of about 10 psi.
19. The method of claim 15 , further comprising attaching a die to the upper surface of the flange, wherein the dielectric frame surrounds the die.