| 摘要 |
<p>1,209,963. Printed circuits. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 17 Jan., 1968 [20 Jan., 1967], No. 2559/68. Heading H1R. [Also in Division C7] In the manufacture of a printed circuit having metallized through holes the printed circuit substrate and conductor forming foil are covered by a protective hydrophobic strippable film prior to the piercing and metallizing of the holes. Example I. (a) A laminated glass fibre reinforced epoxy resin covered on both surfaces with copper foils is coated with a photosensitive lacquer and then developed after exposure to light so that the conductors of the printed circuit pattern to be obtained are not protected. (b) The protected part of the sheet and the positions of the holes to be formed are covered by a plating resist of polymerized lacquer which is coloured so that the places of the holes become visible. (c) A strippable film obtained from a solution of 150 gs./litre nitrocellulose and 30 gs./litre of camphor is coated over the sheet and after drying is dipped in an aluminium stearate solution in toluene of a concentration of 3 gs./litre. (d) After drying the holes are pierced. (e) The walls of the holes are seeded by dipping in a first solution of 0À1 g. of PdCl 2 3mls. of HCl (36%) completed to 1 litre by water and then a second solution of 5À1 gs. of SnCl 2 3À2 mls. of HCl (36%) completed to 1 litre by water. (f) Electroless deposition of copper is then provided by dipping in a solution of 38 gs. of Na-K-tartrate 8À3 gs. of NaOH 5À8 gs. of CuSO 4 .5H 2 O 125 gs. of ethylene diamine tetra acetic acid 34 mls. of formaldehyde (40% solution) completed to 1 litre by water. (g) The strippable film which has no copper coating is pealed off. (h) Copper is electrolytically deposited on the walls of the holes and exposed portions of the copper foil which are to form the conductors and a layer of gold from an acidic gold solution is electrolytically deposited on the copper. (i) The plating resist is removed by dissolution and the copper not coated with gold is dissolved in a solution containing 150 gs./litre of chromic acid 100 gs./litre of sulphuric acid in water. Example II (a) A laminated panel consisting of copper foils and phenol resin impregnated paper is provided on either face with a plating resist as in (a), (b) of Example I. (b) The panel is immersed in a solution of 150 gs./litre of nitrocellulose 30 gs./litre of camphor 1g./litre of aluminium stearate to form a strippable film. (c) The holes are pierced and coated with copper as in (d) (e) (f) of Example I. (d) The strippable film is removed by dissolving. (e) The conductors are formed by operations (h) (i) as in Example I.</p> |
