An experimental investigation of the emissivity of various electronic packages

The radiation emissivities for quad flat pack, ball grid array, metal quad flat pack, and exposed heat slug packages were measured by an infrared pyrometer and a Gier Dunkle infrared reflectometer. Emissivities were also calculated from experiments done in an evacuated bell jar. Experiments were performed to measure an effective emissivity from the entire package and to determine the local emissivity at a specific location on the package. The results indicate that effective emissivities from the entire package range from 0.91 for regular quad flat packs to 0.28 for the exposed heat slug packages. Local emissivities measured were strongly dependent upon the amount of marking ink on the surface of the package. The measured emissivity of the nickel surface of the exposed heat slug was 0.15 when marked with black ink and 0.04 without the marking ink