| 摘要 |
An ultrasonic sensor having a structure allowing a case to be evenly filled with foamable resin, and having a good property is provided. An ultrasonic sensor 10 includes a cylindrical case 12 with a bottom. A piezoelectric element 18 is bonded to an inner side of a bottom 12a of the case 12, and a felt 22 is bonded to the piezoelectric element 18. A cap 24 is fitted to an opening of the case 12. The cap 24 includes a fixing portion 26 and a substrate 28 which is harder than the fixing portion 26. Terminals 36a and 36b are press-fitted to the substrate 28. Wires 38a and 38b are connected to the terminals 36a and 36b, so that the terminals 36a and 36b are electrically connected to the piezoelectric element 18. A through hole 40 is formed in the fixing portion 26. Resin before being foamed is injected from the through hole 40 and then foamed, so that the case 12 is filled with foamable resin 42 while an excess amount of foamable resin 42 is pushed out from the through hole 40.
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