Copper flanged air cavity packages for high frequency devices
An air cavity package includes a flange and a pedestal extending upward from the flange. A dielectric frame is joined to the flange and surrounds the pedestal. The semiconductor die is placed on the pedestal, which reduces the length of the wires joining the die to the leads of the air cavity package.
1. An air cavity package adapted to contain a die, comprising:
a flange having an upper surface;
a pedestal extending upward from the upper surface of the flange; and
a dielectric frame surrounding the pedestal and having an upper surface and a lower surface, the lower surface being attached to the upper surface of the flange with a high temperature epoxy adhesive, a high temperature silicone adhesive, or a thermoplastic polyimide adhesive; and
at least one conductive lead attached to the upper surface of the dielectric frame.
2. The air cavity package of claim 1 , wherein the pedestal and the flange are formed as a monolith.
3. The air cavity package of claim 1 , wherein the pedestal is attached to the upper surface of the flange, and the pedestal and the flange are made from a different material.
4. The air cavity package of claim 3 , wherein the pedestal is made of CVD/diamond, Cu/diamond, CuAl, CuAg, CuW, CuMo, W, Mo, 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 Si 3 N 4 , or metallized AlN.
5. 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 Si 3 N 4 , or metallized AlN.
6. The air cavity package of claim 1 , further comprising a first conductive lead having an upper surface and a second conductive lead having an upper surface, attached to opposite sides of the upper surface of the dielectric frame.
7. The air cavity package of claim 6 , 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.
8. The air cavity package of claim 6 , further comprising the die, which is attached to an upper surface of the pedestal, wherein the die is approximately coplanar with the upper surface of the first and second conductive leads.
9. The air cavity package of claim 6 , wherein the die is joined to a chip carrier which is attached to the upper surface of the pedestal.
10. The air cavity package of claim 1 , wherein the pedestal has a height from about 0.005 inches to about 0.020 inches.
11. The air cavity package of claim 1 , wherein the dielectric frame is made of an alumina ceramic, a polyimide thermoplastic, or a semi-crystalline thermoplastic.
12. A method for forming an air cavity package, comprising:
receiving a flange with a pedestal extending upwards from an upper surface of a flange;
surrounding the pedestal with a dielectric frame, the dielectric frame having an upper surface and a lower surface;
attaching the lower surface of the dielectric frame to the upper surface of the flange using a first attachment composition; and
joining a first conductive lead and a second conductive lead to the upper surface of the dielectric frame using a second attachment composition;
wherein the first attachment composition and the second attachment composition are independently a high temperature epoxy adhesive, a high temperature silicone adhesive, or a thermoplastic polyimide adhesive.
13. The method of claim 12 , further comprising attaching a die to an upper surface of the pedestal, wherein an upper surface of the die is coplanar with an upper surface of the first conductive lead and the second conductive lead.
14. The method of claim 12 , wherein the pedestal is formed by machining, stamping, coining, forging, direct casting, powder metallurgy, combinations thereof, or photoetching.
15. The method of claim 12 , wherein the pedestal is surrounded by the dielectric frame by heating the dielectric frame to a temperature of about 200° C. to about 300° C., maintaining the flange and pedestal at room temperature, and pressing the dielectric frame around the pedestal.
16. An air cavity package, comprising:
a flange having an upper surface;
a pedestal that extends upward from the upper surface of the flange, the pedestal having an upper surface;
a semiconductor die attached to the upper surface of the pedestal; and
a dielectric frame surrounding the pedestal and having an upper surface and a lower surface, the lower surface being attached to the upper surface of the flange;
wherein the pedestal and the flange are made of copper, the dielectric frame is made of a ceramic, and the lower surface of the dielectric frame is attached to the upper surface of the flange by a high temperature silicone adhesive.
17. An air cavity package adapted to contain a die, comprising:
a flange having an upper surface;
a pedestal that extends upward from the upper surface of the flange, the pedestal having an upper surface;
a semiconductor die attached to the upper surface of the pedestal;
a dielectric frame surrounding the pedestal and having an upper surface and a lower surface, the lower surface being attached to the upper surface of the flange with a high temperature epoxy adhesive, a high temperature silicone adhesive, or a thermoplastic polyimide adhesive; and
a first conductive lead having an upper surface and a second conductive lead having an upper surface, attached to opposite sides of the upper surface of the dielectric frame;
wherein the upper surfaces of the first and second conductive leads are coplanar with an upper surface of the die.