SOLDER BEARING EDGE CLIP

Abstract: A solder-bearing edge clip (10) or connector for attachment to a contact pad (12) on a substrate, wherein a compact mass of solder (10, 21) is gripped by the edges of arcuate fingers (18, 19) formed in a thin flat blank of any desired configuration, the axis of the solder wire (30) from which the mass of solder (20, 21) is cut being perpendicular to the plane of the flat blank.

Description: SOLDER BEARING EDGE CLIP This invention relates to a solder bearing edge clip or connector for attachment to a contact pad on a substrate, and particularly to such a clip wherein the solder mass is gripped by the edges of fingers formed in a thin flat blank 5 of any desired configuration, the axis of the solder wire • • being perpendicular to the plane of the blank. Background of the Invention In assembling a substrate (chip) on which conductive paths have been deposited with connecting elements in the 10 nature of terminal clips, it is customary to provide a small quantity of solder at each point where a connector makes contact with a "pad" on the substrate, so that a good electrical path will be established. Several specifically different ways of attaching small solder masses at the 15 critical points are disclosed in Seidler Patent No. 4,203,648 and patents cited therein. In such prior terminal clips or connectors the means for attaching each solder mass comprises a flat finger of thin metal stamped out of the blank and bent tightly around the solder wire 20 which latter is usually cut to form a small cylindrical plug. The axis of the solder has, customarily, extended parallel to the plane of the flat metal blank. With the trend toward miniaturization of circuit- bearing substrates, it has become important to provide 5 terminal clips which can be arranged in close lateral prox¬ imity to each other and a step in that direction is dis¬ closed in Seidler application Serial No. 230,907, filed SUB S TITUTE SHEET February 2, 1981, now Patent No. where each ter¬ minal element is constituted by a finger which retains sufficient material to be adequately conductive and self- sustaining while being narrowed by longitudinal folding. Objects of the Invention It is an object of this invention to provide a solder bearing edge clip wherein each solder mass is held by the oppositely disposed edges of fingers cut or stamped from a flat blank. It is a further object of the invention to provide an array of such edge clips which can be attached to con¬ tact pads very closely spaced along the margins of a circuit-bearing substrate, the edge clips lying in parallel planes, equally closely spaced. It is another object of the invention to provide an edge clip wherein the body of the clip is formed by stamping from flat sheet metal and the solder wire, from which each solder mass is formed, has its axis perpendic¬ ular to the plane of said sheet metal. It is a still further object of the invention to provide certain improvements in the form, construction and arrangement of the several parts by which the above named and other objects may effectively be attained. The invention accordingly comprises an article of manufacture possessing the features, properties, and the relation of elements which will be exemplified in the article hereinafter described, and the scope of the .- •** * τ , * !- ** f" f . invention will be indicated in the claims. Brief Description of the Drawings Practical embodiments of the invention are shown in the accompanying drawings wherein: Fig. 1 represents a perspective view of a single edge clip associated with a substrate portion, shown in broken lines; Fig. 2 represents a similar view of an array of edge clips mounted on a common bandolier; Fig. 3 represents a transverse section on the line m- HI of Fig. 1; Fig. 4 represents a similar section showing the solder mass after melting; Fig. 5 represents a view similar to Fig. 2 showing a first modified form of edge clip and a modified from of bandolier mounting; Fig. 6 represents a view similar to Fig. 1 showing a second modified form of edge strip connected to a supporting strip at one end and a bandolier at the other end; Fig. 7 represents a detail perspective view of two clip fingers with solder buttons mounted therein; Fig. 8 represents a section on the line vm-vm of Fig. 7, and Fig. 9 represents the same section as Fig. 8, before "riveting" of the solder mass. Referring to the drawings, a first form of clip 10 is shown in Figs. 1 to 4, Fig. 1 showing the relation of a SU single clip to an edge portion 11 of a substrate on which a contact pad 12 has been deposited. The contact pad 12 and its counterpart, if any, on the opposite face of the substrate are assumed to be terminals of an electronic circuit (not shown) deposited on the substrate and requir¬ ing connection to other circuit elements for any appropri¬ ate purpose. The clip 10 comprises a body portion 14, shown as having a goose-neck configuration, with spaced arms 15, 16 projecting laterally in the plane of the body to provide a gap 17 which approximates the thickness of the substrate. Each arm terminates in a pair of spaced arcuate fingers 18, 19 and, in the completed clip, each pair of fingers embraces tightly a cylindrical solder mass 20, 21. At its opposite end the clip body is connected to a mounting block 22 having a depending tab 23 which can be fitted in a slot 24 of the carrying bandolier 25 and riveted in place, e.g., by upsetting the ends of the tab as shown at 23' in Fig. 2. The connection of the clip body 14 to the block 25 is marked by a break-away notch 26, for easy removal of the bandolier and mounting blocks when a clip or an array of clips has been soldered in place on a substrate. To manufacture any desired multiplicity of such clips, the blanks (as shown in Fig. 1 but with open fingers and without solder) are stamped from a strip or sheet of metal and are mounted automatically on a carrying bandolier 25. Solder wires 30 are laid between the respective fingers which are then closed tightly enough to indent the softer SUSS STUTE SHEET ^!JRIA OMPI (lead) solder wire, as shown in Fig. 3. The wires are then cut away to remove short sections 31 and leave discrete solder masses firmly gripped between each pair of fingers. As an additional refinement, the clip faces are desirably coated with tin 32, at least in the finger areas, in order to provide a compatible path for the solder to follow, when melted, and thus assure formation of a good electrical bond with the pads on the substrate, as illustrated in Fig. 4. A modified form of clip is shown in Figs. 5 and 6, wherein the body portion 41 is elongated and extends in opposite directions from the arms 42, 43 with fingers 44, 45 as before. In one direction the body portion is a goose-neck 46 and in the other direction it is a flat strip 47 which is bent 90° at 48 and continues to provide a stem end 49 adapted to be frictionally engaged between the elongated parallel lugs 50 of a carrying bandolier 51. Because of the elongated form of the clip, it is desirable to support also the goose-neck end, as shown in Fig. 6, where a break-away connection 52 is provided between the clip and a carrying strip 53. The solder masses 55 correspond to the masses 20, 21 and are formed and attached in the same manner as described above. An alternative form of solder mass is shown in Figs. 1 , 8, and 9 as used in clips of the type shown in Figs. 1 to 6. In this alternative form the solder wire is replaced by solder spheres 60 which are inserted with a friction fit, in apertures 61 formed in the enlarged end c ■ - "^'-. -_ 3 im- r_s_.£ :.τ f OMPI /fa WIPO portions 62 of contact arms 63, corresponding to arms 15, 16, 42 and 43. After insertion the spherical masses (Fig. 9) are upset as shown in Fig. 8 to achieve a two-way mushroom configuration 64 whereby they are very firmly retained in the clip. The contact arm surfaces may be provided with a tin coating 65, for solder flow assistance as mentioned above. In the form shown in Figs. 1 to 4 the maximum thick¬ ness of the clip, before assembly with a circuit chip, is only the length of the solder mass, and this could be reduced by using solder balls as shown in Figs. 7, 8 and 9. That is, the body of the clip is a flat sheet, in a single plane, which permits assembling the clips with a very close pitch, as now frequently required or desired. In the modified clip of Figs. 5 and 6 the over-all width is slightly greater due to the bending of the stem end into a different plane but a relatively close pitch can still be attained since the stem is straight and narrow. It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above article without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. "BU^ ,

Claims: WHAT I CLAIM IS : 1. An edge clip for securement to a contact pad on a circuit-bearing substrate, comprising a clip body portion of sheet metal and a compact mass of solder, the body portion being provided with at least one integral flat element adapted to contact edgewise the mass of solder and shaped to engage with said mass. 2. An edge clip according to claim 1 wherein the body portion is provided with at least one pair of arcuately shaped fingers engaging edgewise the mass of solder. 3. An edge clip according to claim 2 wherein edges of the fingers are indented in the engaged solder mass. 4. An edge clip according to claim 1 wherein the integral flat element is a contact finger traversed by an opening and the mass of solder is spherical and fitted in said opening. 5. An edge clip according to claim 4 wherein the mass of solder is expanded to engage the margins of said opening. 6. An edge clip according to claim 2 wherein there are two pairs of arcuately shaped fingers each engaging a separate mass of solder, the pairs of fingers being spaced to provide a gap adapted to receive the edge of a circuit-bearing substrate. 7. An array of spaced edge clips for securement to the contact pads, on a circuit-bearing substrate, each clip comprising a clip body of sheet metal and a compact mass of solder, each body portion being provided with at SUBSTITUTE SHEET -8- least one integral flat element engaging edgewise the mass of solder. 8. An array of spaced edge clips according to claim 7 wherein the solder masses are cylindrical and have their axes perpendicular to the planes of the clip bodies. SUBSTITUTE SHEET OMPI

Inventors: SEIDLER JACK, SEIDLER, JACK
Applicants: NORTH AMERICAN SPECIALITIES, NORTH AMERICAN SPECIALTIES CORPORATION
Application year: 1983
Main classification: H01R4
IPC codes: B23K1, H01R4, H05K3