| 摘要 |
1,073,108. Circuit assemblies. SIEMENS A.G. Feb. 15, 1966 [Feb. 16, 1965], No. 6477/66. Heading H1R. In a circuit assembly, e.g. an I.F. amplifier or a demodulator, comprising components 6 mounted on a printed-circuit board 4 within a screening housing 2, board 4 is provided with a metallized earthing border region 5 and is surrounded by a U-section metal frame 3 which is soldered to the housing 2 and the earthing region 5. Three sides of the frame 3 are spot welded to corresponding sides of the housing 2; board 4 is slid into place; and the housing is closed by side 2a to which is welded the fourth side 1 of the frame. When screening partitions are used inside the housing (Fig. 2, not shown) the entire frame is placed around the board, and then inserted in the housing to which it is connected by bolts or rivets. In Fig. 3 (not shown), an L-section frame (14) is used, tongues (15) integral with the frame being inserted in loops (13) punched out of the housing walls and secured by being turned over; a transistor (9) is secured by a heat-dissipator (12) to the housing wall. After assembly, the board, the frame, and the housing are joined by dip- or wave-soldering, preferably simultaneously with the connection of the components to the board. To wave-solder an assembly in which the board and the frame are set back from the edge of the housing, oblique fillet strips (17, 20, Fig. 5, not shown) are fitted between the frame and the housing wall at the leading and trailing edges of the solder wave: a slight modification is depicted in Fig. 6 (not shown).
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