GB2251138A - Planar circuit connector - Google Patents

Abstract

A connector 10 for interconnecting the circuit pads 32 of a printed circuit board 30 to pads 42 of a component 40 includes a rectangular frame 12 having notches 16 around its four sides including contact-mounting sections 17 with contacts 20 having legs 23, 24 positioned to frictionally fit on contact-mounting sections 17 within the notches. The contacts 20 include legs 26, 28 projecting above and below the frame 12 to provide surfaces residing in a common plane engaging the pads 32, 40 on the surface of the board and the component. <IMAGE>

Description

PLANAR CIRCUIT CONNECTOR This invention relates to an electrical connector for interconnecting the planar circuits of components and boards, such as integrated or hybrid circuits, to printed circuit boards.

In Japanese Patent Sho 63-53-674, there is taught a typical integrated circuit socket connecting a leadlesstype chip carrier to a printed circuit board. The conventional socket has, in the center, a nearly rectangular insulated housing with a relief to receive the integrated circuit chip and is designed so that flat contacts insert into multiple openings formed at the outer edge of the housing. The contacts are complexly shaped to provide elasticity, making manufacture of the socket difficult when the spacing of contacts is quite small.

Complex stampings are difficult to handle and to assemble, and more importantly, difficult to use in surface mounted applications wherein the contacts reside in a common plane to be soldered to the circuit pads of a circuit board or the like.

The present invention has as an object the provision of a planar circuit connector wherein the contacts are simple, flat metal stampings readily adapted to surface mount use. The invention has as a further object the provision of a planar circuit connector wherein the frame and contacts lend themselves to easy assembly and mass loading. A still further object is to provide a soldertype surface mount connector of low profile and high density, in terms of contact spacing.

The invention achieves the foregoing through the provision of a connector for interconnecting the circuit pads of a printed circuit board, or the like, to the conductive pads of components, including integrated circuit components or hybrid circuit components. Such pads reside in surfaces in a planar disposition intermated through an array of contacts mounted in an insulating frame to position opposing contacts on legs which have a patterned disposition to match the disposition of the contact pads of component and board.The frame of the connector of the invention is generally rectangular and includes a relief in the center thereof adapted to receive projecting elements of the component and further includes notches or recesses extending around the four outside edges of the frame which are closely spaced on the appropriate centers of the conductive paths of board and component and include contact-mounting sections of a generally rectangular cross-section. Contacts are loaded into the notches in a frictional fit provided by interiorly disposed legs which define surfaces fitting onto the contact-mounting sections. The outside edges of the contact-mounting sections limit inward disposition of the contacts, and the upper and lower surfaces of the sections operate to position the contacts in a vertical sense.The contacts further include legs projecting upwardly and downwardly, having contact surfaces thereon, and the contacts are formed of thin flat conductive metal so as to be relatively simple to stamp and form and handle. The inner ends of the contacts of the preferred embodiment include bevels facilitating loading the contacts into the notches onto the contact-mounting sections from the outside of the frame. These legs are relatively short, and the overall size of the contacts is relatively small so as to facilitate positioning the contact surfaces precisely relative to the plane of interconnection of conductive paths of component and board.In a preferred embodiment, the contacts are coated with solder or alternatively, a solder cream, including appropriate flux; it is applied to the contact surfaces of a sufficient thickness so that when the solder is reflowed, or melted, it will bridge any gap due to the non-planarity of disposition of a contact caused by even slight tolerance variations. In one embodiment, the frame of the connector is made to be of a thickness slightly less than the vertical dimension of the contacts and in another embodiment, the frame is made to have a thickness dimension approximately equal to the vertical dimension of the inwardly projecting legs of the contact as measured from the outside thereof for applications requiring a minimum height of component above a given board.

The invention will now be described hereinbelow by way of example with reference to the accompanying drawings in which: Figure 1 is a plan view, substantially enlarged, of a connector of the invention.

Figure 2 is a side, elevational and partly sectioned view of the connector of Figure 1.

Figure 3 is a side, elevational and partly sectioned view of an alternative embodiment of connector of the invention.

Referring now to Figure 1, the invention connector 10 is shown to include a frame 12 preferably of a plastic, insulating and dielectric material molded to include four sides 12a, 12b, 12c, and 12d, arranged in a generally rectangular shape. The frame 12 includes an interior opening 14 which forms a recess adapted to receive devices or modules attached to the component served by the connector in a manner to be described with respect to Figure 2. Each of the sides of the frame 12 includes an array of notches 16 which extend inwardly from the outside edge of the frame beneath the upper surface and the lower surface of the frame in the manner shown in Figure 1 and in Figure 2 at the right-hand end, which is a section taken along lines 2-2 of the view in Figure 1.The notches are in number and disposition positioned along the frame to coincide with the conductive paths on a printed circuit board 30 and a component 40, such paths terminating in conductive pads 32 on board 30 and 42 on component 40, as shown in Figure 2.

The notches 16 include interiorly thereof contactmounting sections 17, as shown in Figure 2, and define a portion of the frame for mounting contacts 20. The contacts 20, as shown in Figures 1 and 2, are comprised of a flat stamping of conductive metal such as phosphor bronze or beryllium copper having a central upstanding leg 22 and a pair of legs 23 and 24 projecting at right angles thereto. The legs 23 and 24 end in bevels shown as 25 in Figure 2 and have an interior dimension 21 adapted to frictionally fit onto the contact-mounting section 17 with the legs 23 and 24 residing in the notches to be held upright. The contacts 20 further include short stub-like legs 26 oriented toward the top of the frame and longer legs 28 extending downwardly at an angle.Each of the legs 26 and 28 includes a contact surface positioned to engage the contact pads of the board and component. Note that the legs end in different vertical positions to accommodate pads on different spacings of the component and board. The surfaces of the legs 26 and 28 reside in planes parallel to, and essentially adjacent, the planes occupied by the contact pads 32 and 42.

In practice, the surfaces of the contacts 20, including particularly the surfaces of legs 26 and 28, are coated with solder and an appropriate flux or alternatively, with a solder cream applied thereto. This may be done just prior to a soldering operation with the frame aligned so that the surfaces of the legs 28 rest on the pads 32 of board 30 and the surfaces of the legs 26 receive the pads 42 of component 40 in alignment. The board 30, loaded with the connector 10 and component 40, may be then heated as by vapor phase heating or in an appropriate oven so that the solder reflows and in essence, bonds the surfaces of legs 26 and 28 to the appropriate pads of board and component.

Because the overall height of the contacts 20 is quite limited, the invention connector can be made quite thin in height and therefore more readily accommodate the necessary tolerances, considering the thickness of solder or solder cream, to make sure that the surfaces of legs 26 and 28 reside essentially in planes for appropriate planar interconnection.

Figure 3 shows an alternative embodiment of a connector 10' having a frame 12' and notches 16' including contact-mounting sections 17'. Contacts 20' are loaded in such notches with the legs 26' and 28' positioned to reside in planes for interconnection to components and boards as previously described. The contacts 20' further include the inwardly directed legs 23' and 24' extending transversely from a central vertical leg 22' which frictionally fit onto the contact-mounting sections 17'.

To be noted in Figure 3 is the thickness of the frame 12', such thickness being on the order of the dimension between the outside surfaces of the legs 23' and 24' and thinner than the frame 12 shown in Figures 1 and 2. The frame 12' provides more vertical clearance between the bottom of the frame and the upper surface of a board 30' (not shown) and an overall reduction in the use of plastic material for the frame. The frame 10' may have a recess similar to recess 14, if desired. In general, the heavier frame 12 is used for connectors having higher numbers of contacts and of a greater outside dimension, and the frame 12' is used for applications having fewer contacts at smaller dimensions.

In one example of a frame 12 or 12', the frame had a square configuration with sides on the order of 21 mm and an overall width on the order of 1.5 mm. The contacts for such frame were on the order of 0.3 mm in thickness and had an overall height on the order of 3.4 mm with the legs 26 and 28 on the order of 0.5 and 0.7 mm, respectively.

These contacts were used in a frame member 12 having a height on the order of 3 mm.

The invention contemplates various changes and modifications in accordance to the specific application, including particularly the numbers of notches and the dimensions of the frame and of the contacts themselves.

The invention also contemplates variations in the shape of the contacts. To be appreciated is the simplicity of the invention contacts and frame and means of holding the contacts with an insertion thereof from the outside of the frame. It is contemplated that this may be done through a gang loading of the contacts on a given side of the frame, with the frame being rotated to be addressed by a further row of contacts prepositioned in a tool or robot or the like. It is also contemplated that the disposition of the surfaces of legs 26 and 28 can be varied from the vertically offset condition shown in Figure 2 to accommodate different pad layouts on board and component.

Claims (7)

CLAIMS:

1. A planar circuit connector for interconnecting the conductive pads of a component to the conductive pads of a circuit of the type wherein such pads reside in planes on the component and circuit, the connector including an insulating frame aaving a plurality of sides with each side having a series of thin notches extending inwardly of the side on the top, bottom, and edge surfaces thereof, a contact-mounting section extending within a notch having top, bottom, and edge surfaces forming a generally rectangular cross-sectional configuration, a thin, flat contact for each notch including first legs having opposing contact surfaces thereon projecting upwardly and downwardly relative to said frame to extend above and below the frame upper and lower surfaces and second resilient legs extending at right angles to said first legs and spaced apart to frictionally fit on said contact-mounting section to position the first leg contact surfaces to reside in common planes above and below said frame to engage the contact pads of the component and circuit.

2. The connector of claim 1, wherein said frame has a thickness slightly less than the height of said contacts as measured from the opposing contact surfaces of said first legs

3. The connector of claim 1,wherein said frame has a thickness approximately equal to the distance between the outside surfaces of said second legs

4. The connector of claim 1,2 or 3,wherein said second legs include beveled portions and ends to facilitate insertion onto said contact-mounting sections and into said notches.

5. The connector of claim 1,2,3 or a, wherein said first legs are offset with respect to an axis perpendicular to the said common plane.

6. The connector of any preceding claim,wherein said frame includes an interior relief to accommodate the portions of a component package extending within said frame.

7. A planar circuit connector constructed substantially as hereinbefore described with reference to Figures 1 and 2 or Figure 3 of the accompanying drawings