| 摘要 |
1,179,753. Electrolytic recording sheets. PHOTOCIRCUITS CORP. 25 Oct., 1967 [27 Oct., 1966], No. 48553/67. Heading D2B. [Also in Division G1] Multilayer printed circuit boards are tested before components are connected thereon for continuity and for short circuits of particular circuit paths through the board by placing the circuit board 2 in contact with electrolyte impregnated or electrosensitive paper 3 between conducting plates 1 and 4; and applying voltage between the plates. Colour indicators are included when necessary in the papers. When electrolyte impregnated paper is used, it acts to remove some metal (a minute amount) from those terminals on the lower face of the board connected to the upper, to produce a colour change at corresponding points in the paper 3. When the paper is electrosensitive, the colour range is achieved without the removal of the terminal metal. The pattern of coloured points can be compared with a standard to assess the integrity of the circuit. Particular circuit paths through the board may be tested for continuity and short circuits by introducing a mask 52 between the top of the board and the plate 1, to select particular terminals on the top, the resulting pattern at the bottom being noted. A sheet 51 of a flexible conductor to penetrate the holes in the mask is provided. Numerous materials suitable for use as electrolytes and indicators in the sheet 3 are suggested. These will be determined to some extent by the metal of the printed board terminals. For example, when the metal terminals are of copper, the electrolyte may incorporate sulphate ion to produce a bright blue colour at activated areas in the paper; with nickel terminals and nitrate ions, a green coloration will result. With terminals covered by a leadtin solder mask, nitrate may be used, resulting in a black lead compound in the paper. Specific colour indicators may be incorporated in the electrolyte - e.g. sodium rhodizonate, which with deplated lead-tin forms a blue coloured complex. Electro-sensitive papers may be starch iodide, catechol &c or may incorporate sodium acetate, ferrous ammonium sulphate and the disodium salt of ethylenediaminetetra acetic acid.
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