Over-mold plastic packaged wide band-gap power transistors and MMICS
View Patent ↗A transistor package includes a lead frame, a wide band-gap transistor attached to the lead frame, and an over-mold surrounding the lead frame and the wide band-gap transistor. The wide band-gap transistor has a peak output power greater than 150 W when operated at a frequency up to 3.8 GHz. Using an over-mold along with a wide band-gap transistor in the transistor package allows the transistor package to achieve an exceptionally high efficiency, gain, and bandwidth, while keeping the manufacturing cost of the transistor package low.
1. A transistor package comprising:
a lead frame;
a wide band-gap transistor attached to the lead frame using a sintered metal die attach material, the wide band-gap transistor having a peak output power greater than about 150 W when operated at a frequency up to about 3.8 GHz; and
an over-mold comprising a plastic or a plastic polymer compound that directly contacts the wide band-gap transistor and that substantially surrounds the lead frame and the wide band-gap transistor.
2. The transistor package of claim 1 wherein the wide band-gap transistor is a gallium nitride (GaN) transistor.
3. The transistor package of claim 1 wherein the wide band-gap transistor is a gallium nitride (GaN) on silicon carbide (SiC) transistor.
4. The transistor package of claim 3 wherein the wide band-gap transistor is a high electron mobility transistor (HEMT).
5. The transistor package of claim 1 wherein the peak output power of the wide band-gap transistor is less than about 1 kW.
6. The transistor package of claim 1 wherein an efficiency of the wide band-gap transistor is greater than about 30%.
7. The transistor package of claim 1 wherein the wide band-gap transistor operates at temperatures greater than 150° C.
8. The transistor package of claim 1 wherein the over-mold has a glass transition temperature greater than about 135° C. and a flexural modulus less than about 20 GPa.
9. The transistor package of claim 8 wherein the over-mold has a thermal coefficient of expansion less than about 50 ppm/° C. at temperatures above the glass transition temperature and a coefficient of thermal expansion less than 18 ppm/° C. at temperatures below the glass transition temperature.
10. The transistor package of claim 9 wherein the over-mold has a moisture absorption rate less than about 0.5%.
11. An over-mold transistor package comprising:
a lead frame;
a wide band-gap transistor with a peak output power greater than about 150 W when operated at frequencies above 2.2 GHz and up to about 3.8 GHz on the lead frame;
an over-mold that comprises a plastic or a plastic polymer compound in contact with a surface of the wide band-gap transistor, on at least a top surface of the lead frame, and extending below the top surface of the lead frame onto at least opposed side surfaces of the lead frame;
wherein the over-mold has a glass transition temperature greater than about 135° C. and a flexural modulus less than about 20 GPa.
12. The over-mold transistor package of claim 11 wherein the wide band-gap transistor is a gallium nitride (GaN) transistor, and wherein the over-mold substantially surrounds the wide band-gap transistor.
13. The over-mold transistor package of claim 11 wherein the over-mold has a thermal coefficient of expansion less than about 50 ppm/° C. at temperatures above the glass transition temperature and a coefficient of thermal expansion less than 18 ppm/° C. at temperatures below the glass transition temperature.
14. The over-mold transistor package of claim 13 wherein the wide band-gap transistor is a high electron mobility transistor (HEMT).
15. The over-mold transistor package of claim 13 wherein the over-mold has a moisture absorption rate less than about 0.5%.
16. The over-mold transistor package of claim 11 further comprising a die attach material between the lead frame and the wide band-gap transistor, wherein a bulk thermal conductivity (K T ) of the die attach material is between about 40 W/m-K and 200 w/m-K, and a flexural modulus (F M ) of the die attach material is less than about 20 GPa.
17. The over-mold transistor package of claim 11 wherein the over-mold transistor package is a monolithic integrated circuit.
18. The over-mold transistor package of claim 11 wherein the over-mold transistor package is a hybrid integrated circuit.
19. A transistor package comprising:
a lead frame;
a wide band-gap transistor;
a sintered silver die attach material bonding to the wide band-gap transistor to the lead frame; and
an over-mold comprising a plastic or a plastic polymer compound that directly contacts the wide band-gap transistor and that substantially surrounds the lead frame and the wide band-gap transistor, the over-mold having a glass transition temperature greater than about 135° C. and a flexural modulus less than about 20 GPa.
20. The transistor package of claim 19 wherein the over-mold has a thermal coefficient of expansion less than about 50 ppm/° C. at temperatures above the glass transition temperature and a coefficient of thermal expansion less than 18 ppm/° C. at temperatures below the glass transition temperature.
21. The transistor package of claim 20 wherein the over-mold has a moisture absorption rate less than about 0.5%.
22. The transistor package of claim 19 wherein a bulk thermal conductivity (K T ) of the sintered silver die attach material is between about 40 W/m-K and 200 w/m-K, and a flexural modulus (F M ) of the sintered silver die attach material is less than about 20 GPa.
23. The transistor package of claim 1 wherein the sintered metal die attach material comprises a sintered silver die attach material.
24. The transistor package of claim 1 wherein a bulk thermal conductivity (K T ) of the sintered metal die attach material is between about 40 W/m-K and 200 w/m-K, and a flexural modulus (F M ) of the sintered metal die attach material is less than about 20 GPa.