| 摘要 |
PURPOSE:To improve out-band attenuation characteristics of a surface acoustic wave element by limiting the difference in height between the wire bonding surface of a lead terminal and the top surface of a metallic stem to within a specific range, recessing the element adhesion part of the stem surface, and specifying the difference between the top surface of the element and the top surface of the stem after adhesion within said range. CONSTITUTION:For example, when the height of lead terminals 2 and 3 is set to zero, the mutual inductance of a wire is reduced to about a quarter as large as that of a conventional package. The substrate of a surface acoustic wave element 7 for a high frequnecy band is generally 0.3-0.4mm thick, so the difference is set to <=0.2mm, thereby obtaining the effect of reduction in the direct coupling quantity between the input and output. Further, the stem surface 12 of the part where the element is adhered is made low in a recessed shape and the top surface of the element after adhesion is made as high as the top surface 13 of the stem. Consequently, the quantity of direct coupling between the input and output is reduced to a level which can be ignored when the height of the lead terminal is zero as well. Further, when the difference in height between the top surface of the element and the top surface of the stem after adhesion is <=0.2mm, the effect of the reduction in coupling quantity is obtained as well.
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