| 摘要 |
PROBLEM TO BE SOLVED: To solve the following problem: a noise countermeasure is difficult to be made compatible with heat radiation, when forming different insulating layers coplanarly and smoothly. SOLUTION: The circuit board includes a metal substrate 1, the first insulating layer 2 formed intermittently on the substrate 1, the second insulating layer 3 formed in a portion not formed with the first insulating layer 2 on the substrate 1, and metal foils 4 formed respectively on the first insulating layer 2 and the second insulating layer 3, 0.1% or less of bubble is contained per a unit cross section of the first insulating layer 2, and 10% or more to 80% or less of bubble is contained per a unit cross section of the second insulating layer 3. The second insulating layer is preferably formed of an epoxy resin, a curing agent, an inorganic filler and the bubble. The curing agent is preferably a phenol novolac resin. COPYRIGHT: (C)2011,JPO&INPIT
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