PLATING DEVICE FOR MINUTE PORTIONS OF CONNECTOR TERMINALS

Abstract: This invention relates to an electro-plating device which is suitable for plating minute portions on protruding tip ends of a connector terminal (10). This inven­ tion device uses either a plating solution supplying member in the form of a thin box which is erected upon a plating solution supplying box and which has a thickness small enough to be inserted between opposing plating areas. The plating areas are a pair of protruding tip ends of the connector terminal which move in contact with or near the supplying member or a plating solution (18) supplying member (13) in the form of a substantial arrowhead shape which has sloped guide planes on both sides and which a top portion can be inserted between opposing plating areas. In the former: the plating solution supplying member comprises a combination of a supporting member made of an insulating sheet having a vertical section substantially shaped like an inverted letter U and a plating solution retaining member of a net or porous sheet which is supported by the supporting member to drape over the outer surfaces thereof. The supporting member is bored with plural holes for supplying plating solution which are arranged discretely in the longitudinal direction at the positions corresponding to the plating areas or close thereto. The plating solution is constantly supplied to the plating solution retaining member via the plural holes to seep thereon. The plating areas are electro-plated at minute portions thereof by contacting with the plating solution which is seeped out of the retaining member. In the latter: a plating solution supply member comprises a support member, anode (19), net member (16) and winding means (32). The support member has a top portion substantially forming an arrowhead with slanted guide planes on both sides. An opening is provided at or near the tip of this top portion to allow seepage of the plating solution. The net member covers the top portion of the support at its tip as well as the surface in its vicinity, the net member being freely wound up in the direction intersecting the passage line by the winding means and forming a supply section for the plating solution at a location corresponding to said passage line. With this construction, minute target portions are contacted with the plating solution which seeps on the net member while preventing the net member from being worn at given locations.

Description: Connector terminals are formed in plurality in the form of comb teeth arranged on a continuous band like member having pilot holes and respectively provided with a pair of projections each having a minute area (e.g. 1 mm² or less) at the end thereof which has to be plated. Various techniques have conventionally been employed for plating these minute portions. For instance, there have been known as typical plating devices such as the plating device which dips the whole end portion including the projections in the plating solution contained in a bath to conduct plating by controlling the liquid level to limit plating areas, or the injection plating device which shields the portions not to be plated with a mask and plates unmasked portions by jetting the plating solution on them (refer to Japanese Patent Application laid-open Nos. Sho 59-126784, Sho 57-161084, and Sho 55-83180). All of the prior art plating devices have drawbacks, however. In the case of the former device, as the whole ends of a connector terminal including the projections which are the subject of plating are plated because a minute plating area is difficult to clearly define, the consumption of plating metal unavoidably increases. This presents a problem when the plating metal is a precious metal such as gold. In the latter case, masking is extremely difficult especially when the subject area is not even but irregular, bent, or complicated. The plating area is not clearly defined by the device to thereby incapacitate sufficient reduction of metal consumption. The present inventors proposed an improvement for brush plating method (Japanese Patent Application Sho 60-89016) wherein the surface of an insoluble anode is covered with a liquid retaining member which can constantly be supplied with plating solution, the plating device is configured to be in alignment with the interval between adjacent fork-like ends of a connector terminal so that the tip end portions of the connector terminal may be plated while moving in contact with the member retaining the plating solution. As the proposed technique is effective in plating only the portions of the connector terminal ends which actually contact with the member on the anode surface, it may be called a minute partial plating method as against the prior art methods which allow only partial plating, achieving a remarkable reduction in precious metal consumption and precise definition of plating area From the JP-A-58 224 193 a plating device is known, whereby the plating solution supplying member consists of a disc rotating around a horizontal axis, the lower portion of the disc being immersed in a plating solution bath by which it is moistened. The plating areas of the components which are to be plated and which are continuously moving along a passline are brought into contact with the disc, with the contact surface of the disc portion immersed in the solution bath being diametrically opposite to the plating areas. By the rotation of the disc, the plating solution absorbed in the plating solution bath is transferred to the plating area. The plating solution and the component are connected with an anode and a cathode, respectively, in a manner known per se. After the moistened disc portion emerges from the plating solution bath, the superfluous solution drips off from the disc while the disc rotates towards the plating areas. I.e. the amount of the applied plating solution depends among other things on the solution retainability and the rotational speed of the disc. The object of the invention is to provide a plating device suitable for constantly supplying the plating areas with an optimum amount of fresh plating solution. According to the invention this object is solved by the characterizing features of the new claim 1. The design of the plating device according to the invention allows the plating solution to be continuously supplied to the plating areas by use of a pump means via a supporting member, a passage and a plating solution retaining member. The supplied amount of the plating solution can in a simple way be adjusted and kept constant via the pump. The plating solution retaining member is continuously wound up or payed out by winding means so that an excessive wear of the retaining member is prevented and its solution retainability is kept on the same level. Advantageously, an anode is provided either inside the passage, near the inlet thereof or inside the solution supplying box. In this manner a plating solution supplying section can be provided in a manner to be able to constantly supply fresh plating solution in the optimal amount to the corresponding portions of the target plating areas on the passage line. The target areas can be supplied with the plating solution evenly over the whole areas when closely contacting with or approaching the supplying section. The net member is driven to move either continuously or intermittently in the direction intersecting the passage line by the driving rollers and reeled in for an appropriate length. In this manner, a suitable length of fresh sheet of the net member is constantly formed as the supplying section. This helps avoid wear and tear of particular locations of the net member sheet. Preferred embodiments of the invention are described below with reference to the drawings in which: Fig. 1 is a schematic perspective view showing a first embodiment of the plating device according to the invention; having an substantially U-shaped vertical section FIG. 2 is an enlarged perspective view of the essential portions of the plating device in FIG. 1; FIG. 3 is a perspective view to show winding state of a plating solution retaining member; FIG. 4 is an enlarged perspective view showing a second embodiment of the plating device; FIG. 5 is an enlarged perspective view showing a third embodiment of the plating device; FIG. 6 is a partial perspective view showing a thin plate (anode) shown in FIG. 5; and, FIG. 7 is a coss sectional view showing a fourth embodiment in essential parts. Fig. 8 is a perspective sectional view of a plating device according to the invention having a substantially arrow-shaped vertical section. FIG. 9 is a sectional view from the direction indicated by the arrow B in FIG. 8. FIG.10 is a partially enlarged sectional view of the support member shown in Fig.9; and, FIG.11 is a schematic perspective enlarged view of another embodiment of the support member. The plating solution supplying member is configured to have a vertical section shaped substantially like an inverted U in the embodiments shown in FIGs. 1 through 7 while it is configured to have a substantial arrowhead shape having sloped guide planes on both sides in the embodiments shown in FIGs. 8 through 11. In order to distinguish one from the other the embodiments shown in FIGs. 1 through 7 are referred to as the "first group invention" and those shown in FIGs. 8 through 11 as the "second group invention". The first group invention will now be described by way of preferred embodiments. The same reference numerals and symbols denote the same components in the embodiments, and overlapping description is omitted. The first embodiment Referring to FIGs. 1 through 3, the first embodiment will be described. Connector terminals 10 which are the subject of plating are formed in plurality in the form of comb-teeth on the lower portion of a continuous band-like member 22 and are respectively provided with fork-like ends extending in the direction perpendicular to the longitudinal direction of the band-like member 22. The areas which have to be plated ll are a pair of tip surfaces of the forked ends which oppose to but apart from each other with an interval which converges at the middle and then again diverges to define a substantial triangle therebetween. Those two areas ll are concurrently plated as a pair, but for the sake of simplicity of description, one of the areas or the right side portion alone will be denoted with the reference numeral ll hereinafter, and when explanation is needed for the both, the reference numerals are repeated like plating areas ll,ll. The plating area ll is adapted to move along a passage line 23 by a combination of a sprocket 26 and a roller 27 which is pressed against the sprocket 26. The sprocket 26 has pins 25 provided on the circumference thereof to freely fit in pilot holes 24 of a continuous band-like member 22. The roller 27 is connected to a cathode power source 28 to cathodize the connector terminals l0. A plating solution supplying member l3 is arranged along the passage line 23 and comprises a combination of a supporting member l5 and a plating solution retaining member l6 which is erected on a plating solution box l2 with a supporting plate 29. The member l3 has a rectangular shape of a small thickness. The supporting member l5 made of an insulating sheet is thin and yet strong enough as a core to be able to support the plating solution retaining member l6. The member l5 is formed to have plating solution passage l4 of a minute width between adjacent teeth. The supporting member l5 has a vertical section shaped substantially like an inverted letter U to cover the passage l4 in order to reduce the platable area. The member l5 is preferably made of a sheet of Tetron (trademark) or of Mylar (trademark). Spacers 30 are provided inside the supporting member l5 in a space corresponding to the passage l4 for the plating solution to extend vertically in the form of tape. If a sheet of insulating material is folded into two to accommodate the thickness of a spacer 30, then narrow passage l4 is made for plating solution each between adjacent spacers 30. The spacers 30 act as rectifiers for the flow of the plating solution l8 inside the passage l4. At the top of the folded member l5 are provided plural solution supplying holes l7 in the longitudinal direction as the "members corresponding to moving plating areas ll,ll on both sides". The plating solution retaining member l6 is supported by the supporting member l5 to drape over the side surfaces thereof. In the embodiment shown in the figure, the member l6 is made of a polypropylene net, but it may be made of porous sheet similar to a net so long as it allows the plating solution l8 supplied thereto via the holes l7 to seep so that the optimal amount of the solution l8, neither more nor less than necessary, is supplied onto the plating area ll which contacts therewith. The plating solution supplying member l3 comprising a solution retaining member l6 held over the supporting member l5 has an extremely narrow thickness (t) to correspond the distance (ℓ) between two opposing plating areas ll,ll of the forked ends of a connector terminal l0 which is as small as 0.38 mm, for example. The passage l4 inside has similarly narrow width (for instance 0.l - 0.2 mm). The thickness is determined so that the plating solution supplying member can be inserted between the opposing areas ll,ll to allow them to contact with the solution retaining member l6 near the top thereof. As the plating areas ll,ll either contact or come very close to the solution retaining member l6 while moving along the passage line 23, the member l6 might be worn out after a long term use. The solution retaining member l6 is wound around winding devices 3l,32 outside the supporting member l5 so that a new sheet of the member l6 constantly covers the surface of the supporting member l5 as one of the winding devices undoes the sheet while the other winds it. The plating solution supplying member l3 is erected on a box l2 and a supporting plate 29 is used to assemble the supporting member l5 and the solution retaining member l6 draped thereon. The plate 29 is provided with a pair of holder/guides 34 which holds the retaining member l6 on the supporting member l5 from both sides and guides the lower portions 33 of the connector terminals l0 as it moves. The pressure against the member l6 applied by the pair of the holder/guides 34 is released when a new sheet is reeled out as mentioned above. The holder/guides 34 are sloped at the upper portion 35 so as to accommodate the same to the form of the lower portions 33 of the connector terminals l0 as well as to guide them while the connector terminals l0 move. However, the portions 33 do not necessarily contact with the upper portions 35 of the holder/guides 34 to be guided thereby. Inside the box l2 which is closed with the supporting plate 29 is provided an anode l9 of platinum in the form of a net which is connected to an anode power source 36. Description will now be given to the operation of the first embodiment of the plating device suitable for minute portions of a connector terminal. The connector terminal l0 is cathodized and guided via the sprocket 26 and the roller 27 to move in the direction from right upper side toward left lower side in FIG. l, and the plating areas ll,ll move along the passage line 23 to contact with or come very close to the plating solution retaining member l6. When the plating solution l8 inside the box l2 is pumped out by a pump (not shown), the solution l8 is forced to go up in narrow passages inside the passage l4 and between adjacent spacers 30, flow out to the outside of the supporting member l5 from the holes l7 near the top of the member l5, and seep into the pores or mesh of the solution retaining member l6. When the plating areas ll,ll contact with or come close to the solution retaining member l6, the tips 20 of the triangles of areas ll,ll are positioned at or close to both sides of the top of the solution retaining member l6 to contact with the plating solution l8 freshly supplied from the holes l7. In this manner, an optimal amount of the plating solution l8, not more or not less than the necessary amount, is supplied substantially evenly on limited locations of the plating areas ll,ll, more particularly the locations near the tips 20, and other locations 2l adjacent thereto. In this manner, a minute portion of the respective plating areas including the tip 20 of and adjacent locations 21 of the protruding portion can be specifically plated in a substantially even thickness. The embodiments 2 through 4 will now be described. The second embodiment Although in the first embodiment, a platinum anode 19 in a net form is provided with a box 12, in the embodiment 2 in FIG. 4, a platinum net member 37 is interposed as an anode in the solution passage 14 inside the supporting member 15. The net member 37 is connected to an anode power source 36 and is positioned to extend from the inside space 38 of the box 12 to the solution passage 14. Wefts 39 and warps 40 are woven in the inside space 38, but warps 40 alone are erected at a small interval in the solution passage 14 to minimize the thickness of the anode. When pressure is applied on the solution 18 in the space 38, the solution is forced to go up through narrow passages 41 between the solution passage 14 and between the respective warps 40, and to seep onto the surface of the solution retaining member 16 from the holes 17. The warps 40 extend to the holes 17 at the top thereof respectively so that the distance between the "anode" and the plating area ll is kept extremely short. They therefore can have the function of the spacers 30 of the first embodiment, i.e. the function to rectify the flow of the plating solution l8 and minimize the width of the passage l4 when the said passage l4 is formed by folding the insulating sheet into an inverted U letter. The third embodiment FIGs. 5 and 6 show the third embodiment. While the first and second embodiments use a net member 37 as an "anode", a thin plate 43 having vertical slit-like passages 42 in a plural number is employed as an "anode". The thin plate 43 is inserted into the supporting member l5 which is folded like a letter U . When held tightly between the both sides of the member l5, the lower portions 44 of the passages 42 communicate with the inside space 38 of the box l2 while the upper portions 45 communicate with the holes l7. The width of the passages 42 is designed to be an extremely small value so as to facilitate the upward flow of the solution l8 from the inside space 38 to the holes l7. The thin plate 43 has the same function as the spacers 30. The fourth embodiment FIG. 7 shows the fourth embodiment. While the position of an "anode" in the first embodiment is inside the box l2, and in the passage l4 in the second and third embodiments, a platinum net member 46 is arranged near an inlet of the passage l4 as an "anode" in the fourth embodiment. The plating device suitable for plating minute portions of connector terminals according to the first group invention can achieve various effects such as: (A) As the plating solution supplying member comprises a combination of a supporting member made of an insulating sheet and a solution retaining member made of a meshed or porous sheet, the thickness can be easily minimized in manufacturing process to the extent that allows insertion of the supplying member between a pair of plating areas of a connector terminal which oppose each other across an extremely narrow distance. (B) As a solution retaining member is used to supply the plating solution to a pair of plating areas which contact with or come close thereto, the plating solution conveniently seeps out from the member after it is fed via holes, and the amount of the plating solution to be supplied onto the plating areas can be controlled at the optimal value. (C) As the plating solution is applied only to the locations to be plated, and these locations alone are electro-plated, even minute portions can be specifically plated. (D) As the plating solution can be forced to pass through passages of minute width which are provided all over the inside of the supporting member to contact with the anode disposed either inside the passage, at the inlet of the passage or inside the box and to seep out from the holes via the retaining member, the plating solution can be constantly supplied for continuous plating process. (E) Due to the synergistic effects of the above four, this invention device can effectively electro-plate minute portions of a pair of plating areas of a connector terminal. Next, the embodiment of second group invention will be described. First, a plating solution supply member lll in a plating device ll0 comprises a support member ll3 mounted and fixed on a plating box ll2, an anode ll4, a net member ll5 and a winding means ll6. The support member ll3 is made of an insulating material and mounted and fixed on a cover plate ll7 of the plating box ll2. The top portion ll9 of the support member is substantially in the form of an arrowhead with two slanted sides forming guide planes ll8. An opening l22 is provided at the tip l20 of the top portion ll9 to allow a plating solution l2l to seep therefrom. A passage l23 for supplying the plating solution communicates with the opening l22 and forms a through-hole within the support member reaching the bottom l24. The passage l23 also communicates with an opening for supply (to be described hereinafter) provided in the plating box ll2. The anode ll4 is made of a reticular material so as not to prevent flow of the plating solution l2l. The anode ll4 is attached to the underside of the cover plate ll7 at the opening l26 in the vicinity of the bottom l24 of the support member ll3 as well as of an inlet port l25 for supplying the plating solution. The net member ll5 covers the top portion ll9 of the support member ll3 at the tip l20 and can freely move to be wound in the direction (indicated by the arrow A) which intersects a pass-line (indicated by the arrow PL in the drawings) to form a supply section l27 for the plating solution l2l. The winding means ll6 each is provided on either side of said pass-line PL and comprises a guide roller l28 which imparts tension to the net member ll5, a rotatable press roller l29 and a drive roller l3l connected to a motor l30 which winds up and pays out the net member ll5 in a direction intersecting (indicated by the arrow A) the pass-line PL so that a fresh sheet of the net member ll5 is constantly supplied to contact with the plating target portions l04 of a connector terminal l02. Reference numerals l32, l33, l34 and l36 respectively denote a pump, a pipe, a plating solution controlling tank and a plating bath. These members are used to pump out, recover and recycle the plating solution l2l. The operation of the device will now be described. The connector terminal l02 to be plated is cathodized by a means not shown and moved to a position so that the plating solution supply member lll can be interposed between the pair of portions l04 to be plated. The plating solution l2l is in the meantime pumped out by the pump l32 to flow through the energized anode ll4 and seep out via the supply opening l26, passage l23 and opening l22, where the plating solution is soaked by the net member ll5 which covers the opening l22 under tension imparted by the guide roller l28. Thus the portion of the net member ll5 which is disposed at the tip l20 of the top portion ll9 and which corresponds to the passage line PL of the target portions l04 is constantly supplied with an optimum amount of fresh plating solution l2l, constituting the supply section l27 of the plating solution l2l. The net member ll5 is pulled by the roller and is free from so called slackening. The target portions l04 of the connector terminal l02 contact with or approach the net member ll5 under tension constituting the supply section l27 and come in contact with the plating solution l2l seeping out the surface l35 of the net member ll5, whereby uniform plating can be obtained over the entire area of the target portions l04. As the plating process completes, the drive roller l3l is rotated by the rotation of the motor l30 to move the net member ll5 via the pressing roller l29 in the direction intersecting the passage line PL (the direction of the arrow A) for winding up the net member by a suitable length. This provides the supply section l27 anew. Although the net member ll5 is wound up intermittently in accordance with the timing of the plating in this embodiment, it is also possible to continuously wind up the net member ll5 during plating to shift the section. In this manner, the net member ll5 can be protected against partial wear occurring at a given portion. FIG. ll shows another embodiment of the support member. The support member l4l used in the plating device l40 has plural openings l44 along the longitudinal direction of the support member l4l in the vicinity of the tip l43 of the top portion l42 of the support l4l. The anode l45 with its lower portion comprising woven warps l46 and wefts l47 and the upper portion warps l46 alone is provided in the passage l23 to function in the same manner as the opening l22 and the anode ll4 of the first embodiment. As the rest of the second embodiment is identical with the first, the description is omitted. Although the anode is disposed in the vicinity of the inlet port l25 of the passage l23 or erected in the passage l23 in the foregoing embodiments, it is also possible to utilize the support ll3 itself as the anode by plating the same with a metal which is insoluble in the plating solution l2l. As has been described, the plating device of the second group invention with its features will bring about numerous advantageous effects such as the following: (a) As the supply section is formed at a position corresponding to the pass-line of the target portions to be plated and where the plating solution is constantly supplied afresh in the optimum amount, the plating solution comes in contact only with the target portions, leaving the remaining portion intact. What is more, as the optimum amount of plating solution is applied via the net member solely to the target portions, plating of unnecessary portions or unnecessary thickness can be avoided, resulting in reduced consumption of the precious metal. When compared with the conventional plating technique in which not only the target portions in the form of fork-like member but the portions near the target portions are also plated, the device of the present invention results in reduction of precious metal consumptin and thus of the cost; (b) As the net member is wound up by a suitable length in the direction intersecting the pass-line to provide a fresh sheet of the supply section, the net member can be protected against partial wear at a given location; and, (c) The device can be adapted to various applications by modifying the inclination, size and configuration of the support member at its top portion according to the shape and size of the objects to be plated.

Claims: A plating device for electro-plating minute portions of connector terminals each of which has a pair of plating areas to be plated and opposite to each other, comprising a plating solution supplying member which can be moistened by a plating solution and which is inserted between the two parts forming a pair of plating areas to electro-plate these areas while they are moving along a pass-line by either coming into contact with the plating solution supplying member or passing in a small distance thereto, characterized in that said plating solution supplying member (13, 111) comprises a supporting member (15, 113, 141) with a substantially U-shaped or substantially arrow-shaped vertical section having at least one opening (17, 122, 144) for allowing the plating solution to seep out and a passage (14, 123) communicating with said opening (17, 122, 144) for supplying the plating solution by use of a pump means (132) to a plating solution retaining member (16, 115) made of meshed or porous sheet which is supported by said supporting member (15, 113, 141) and which drapes at least over the top portion (119, 142) of the outer surface thereof, wherein said plating solution retaining member (16, 115) can be wound in a direction parallel to or in a direction intersecting said pass-line of said connector terminals (10, 102) by a winding means (31, 32; 116). A plating device according to Claim 1, characterized in that a plurality of openings (17, 122, 144) is provided at or adjacent the top portion (119, 142) of the supporting member (15, 113, 141). A plating device according to Claim 1 or 2, characterized in that said plating solution supplying member (13, 111) is arranged upon a box (12, 112). A plating device according to any one of the preceding Claims, characterized in that the top portion (119, 142) of said substantially arrow-shaped supporting member (15, 113, 141) has slanted guide planes (118) on both sides thereof. The plating device as claimed in any one of the preceding claims, characterized in that the supporting member (15, 113, 141) is provided with a plurality of spacers (30) in the form of tape inside the passage (14, 123), the width of the passage (14, 123) is determined in accordance with the thickness of a spacer (30), and each spacer (30) functions as a rectifier for the flow of the plating solution inside the passage (14, 123). The plating device as claimed in any one of Claims 2 to 5, characterized in that the plating solution supplying member (13, 111), when arranged upon the box (12, 112), is held tightly from both sides with a pair of holder/guides (34), and the top portions of the holder/guides (34) are shaped corresponding to the shape of the lower portions (33) of a connector terminal (10, 102) so that the lower portions (33) thereof can be guided by the top portions while moving along the passage (14, 123). The plating device as claimed in any one of Claims 1 to 6, characterized in that an anode (37) is inside the passage (14) in order to rectify the flow of the plating solution therethrough and to minimize the width of the passage (14, 123). The plating device as claimed in any one of Claims 2 to 6, characterized in that the anode is designed as a net member (19) made of platinum which is positioned inside the box (12, 112). The plating device as claimed in any one of Claims 2 to 7, characterized in that the anode is designed as a net member (37) made of platinum which extends from the inside of the box (12, 112) to the inside of the passage (14, 123). The plating device as claimed in Claim 9, characterized in that the anode made of a platinum net member (37, 145) comprises woven warps (40, 146) and wefts (39, 147), said warps (40, 146) are erected without wefts (39, 147) at the portion inside the passage (14, 123) to facilitate the plating solution to flow upward through narrow passages (41) between adjacent warps (40, 146) inside the passage (14, 123). The plating device as claimed in any one of Claims 2 to 7, characterized in that the anode is formed as a thin plate (43) having a plurality of vertical slit-like passages (42) and extending from the inside of the box (12, 112) to the inside of the passage (14, 123), and the slit-like passages (42) communicate with the inside of the box (12, 112) at the lower portions (44) thereof and with the openings (17, 122, 144) at the upper portions (45) thereof. The plating device as claimed in any one of Claims 1 to 6, characterized in that the supporting member (15, 113, 141) is made of a metal which is insoluble in the plating solution and constitutes the anode. The plating device according to any one of the preceding Claims, characterized in that said winding means (31, 32, 116) is provided with a guide roller (128) for imparting tension to the solution retaining member (16, 115) so that the member comes in close contact with the top portion (119, 142) of the supporting member (15, 113, 141) and with drive rollers (131) which wind up and pay out the solution retaining member (16, 115) freely.

Inventors: MURATA, YASUTO, TEZUKA, JUNICHI, YAMAMOTO, KENJI
Applicants: ELECTROPLATING ENGINEERS OF JAPAN LIMITED
Application year: 1986
Main classification: C25D5
IPC codes: C25D5