| 摘要 |
<p>A multilayer substrate 200,300 is formed of stacking conductive layers 12, 14, 16, 18 and insulating layers 20,22, 24, 26 on either side of a thick conducting core 110, preferably comprising a metal. The core is thicker than the conducting layers. This core layer provides a thermal path, which may aid cooling of components such as 130 that may be in cavity 111. A first signal line 14a, that is part of a conductive layer adjacent to the core is aligned with a recessed portion 10a facing the first signal line, so that the intermediate insulating layer 22 is thicker in the recess area 10a. The signal line may comprise a spiral inductor as figures 8a,8b show and the recess shape and depth will partly control the inductance of this element. Figures 4a and 4b show how the signal line 14a may be spaced apart from all neighbouring conductive layers, which may include ground layers forming a signal transmission lin with a controlled characteristic impedance. The multilayer substrate may comprise a RF module (210, figure 5) and may include duplexers, filters, ICs etc. and figures 6 to 7b show details of the circuit traces formed in the conductive layers.</p> |
