GB2089147A

GB2089147A - Insulation displacement connector and housing

Info

Publication number: GB2089147A
Application number: GB8136492A
Authority: GB
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1980-12-05
Filing date: 1981-12-03
Publication date: 1982-06-16
Also published as: JPS57121173A; KR830008425A; EP0055876A3; BR8107870A; EP0055876A2

Abstract

A discrete wire insulation displacement connector includes a terminal (16) including an insulation displacement contact comprising a pair of blades defined by a line of cut. The edges of the contact ride in a guide channel (22) in the connector housing (14). The housing (14) includes a pair of opposed sidewalls (18) joined by a pair of opposed spaced webs (40) and a pair of opposed spaced endwalls 32 having upper edges below the upper edges of the webs. A tapered access to the connector is defined by at least one flexible prong (24) integrally joined to each of the sidewalls (18) and extending inwardly in opposed relationship. The trailing edges (26) of the prongs cooperate with the upper edges (42) of the webs to create an improved strain relief. <IMAGE>

Description

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GB 2 089 147 A 1

SPECIFICATION

Discrete wire insulation displacement connector

5 This invention relates to an electrical connector, and, more particularly, to a connector which includes an insulation displacement contact for individual or mass termination of discrete wires having improved reliability and strain relief.

10 U.S. Patent 4,159,158 discloses and claims an electrical connector of the insulation displacement type for terminating discrete wires. The sidewall of the connector housing is provided with external ribs, the upper ends of which are arrow-shaped. The 15 trailing edges of these adjacent arrow-like portions provide a constriction for receiving a wire to be terminated while also serving as a strain relief forthe wire when an upward tensile pull is applied to it. These arrow-like members are moulded as a rigid 20 integral part of the connector housing. They are relatively inflexible and may not provide effective strain relief for a range of wire sizes.

According to the invention, there is provided an electrical connector comprising a housing having a 25 pair of opposed sidewalls, each of which has at least one prong integrally joined thereto adjacent the upper edge thereof, the prongs extending inwardly in opposed relationship to define a tapered access for a discrete wire; a pair of opposed lower end walls 30 joined to said sidewalls forming a lower elongate cavity; a pair of opposed webs spaced from said endwalls joining said sidewalls and having upper edges above the upper edges of said lower end walls; and a terminal, including an insulation dis-35 placement contact having a pair of blades defined by a line of cut, mounted between said sidewalls in parallel spaced relation to said webs, said blades being arranged to receive and terminate a wire inserted therebetween.

40 There is further provided an electrical connector comprising a housing having a pair of opposed sidewalls and at least one interior wall spaced from and parallel to said sidewalls to define a plurality of discrete cavities; each of said sidewalls and the or 45 each interior wall having at least one prong integrally joined thereto adjacent the upper edge thereof on each face adjacent one of said cavities, the prongs extending inwardly into said discrete cavities in opposed relationship to define a tapered access 50 thereinto for a discrete wire; a pair of opposed lower end walls joined to said sidewalls and the or each interior wall to form a plurality of lower elongate cavities; a pair of opposed webs spaced from said endwalls joining said sidewalls and the or each 55 interior wall having upper edges above the upper edges of said lower end walls; and a terminal located in each of said cavities, each said terminal incuding an insulation displacement contact having a pair of blades defined by a line of cut. 60 In a preferred embodiment, the contact includes a strain relief aperture at the base of the cut, and the edges of the blades are tapered inwardly to provide a "V" shaped entry to the cut. The terminal is mounted in the connector between the sidewalls in 65 parallel spaced relation to the webs with the blades arranged to receive and terminate a wire inserted therebetween.

In one embodiment of this invention, each of the sidewalls has a generally vertical slot in opposed 70 relationship extending downwardly from the upper edge to an intermediate termination, the opposed slots defining a guide channel. The edges of the contact are tapered outwardly and ride in the guide channel. In operation, the guide channel prevents 75 the blades of the contact from skewing as a wire is being terminated.

The electrical connector of this invention may be produced as a single unit or it may be part of a multiunit component for terminating a plurality of 80 discrete wires. It is capable of terminating a wide range of wire sizes, e.g., 22-30 awg, either solid or stranded, and the upper edges of the webs in cooperation with the inwardly turned prongs provide a substantially improved strain relief feature. 85 In the accompanying drawings:

Figure 1 is a perspective view, partly in section, of a preferred embodiment of a connector according to the invention;

Figure 2 is a sectional view taken along the line 2-2 90 of Figure 1 showing a discrete wire terminated in the connector;

Figure 3 is a sectional view taken along line 4-4 of Figure 2 showing a wire about to be terminted, i.e. inserted, between the insulation displacement con-95 tacts;

Figure 4 is a sectional view taken along line 4-4 of Figure 3 showing the position of a wire having been terminated;

Figure 4a is a sectional view similar to Figure 4 100 showing the position of a large wire having been terminated;

Figure 5 is a sectional view taken along line 2-2 of Figure 1 showing wire position after mid-span termination;

105 Figure 6 is an elevational view of a terminal forming part of the connector according to the invention; and

Figure 7 is a schematic representation of the interrelationship between the force deformation 110 curves for a family of wires and the force displacement curves of the insulation displacement contacts.

As used hereinafter, the term "IDC" shall mean an insulation displacement contact. Thus, the term "IDC" connector" shall mean an electrical connector 115 having an insulation displacement contact for terminating discrete wires or ribbon cable prepared at an end to appear as discrete wires.

As shown in Figures 1 and 2, an electrical connector 10 is in the form of an IDC connector for 120 disengagably connecting individual wires 11 to spaced terminal posts 12which can be mounted in and extended from a backplane or any other suitable place. The connector comprises a housing 14 which may include one or more terminals 16.

125 The housing 14comprises a pair of opposed exterior sidewalls 18. One or more interior walls 20 may also be provided depending on where the connector is to be used and the number of wires which are to be terminated. Each of the exterior 130 sidewalls 18 and interior walls 20 has an upper edge

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GB 2 089 147 A

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22 to each of which are integrally joined at least one prong 24. In a preferred embodiment of this invention each sidewall 18 has two prongs 24 integrally joined thereto on the inner face thereof and each 5 interior wall 20 has two prongs 24 integrally joined thereto on each face thereof. As shown in Figures 3 and 4, prongs 24 are turned inwardly in opposed relation to each other defining a tapered access to the connector for a discrete wire 11. Prongs 24 are 10 flexible and will bend outwardly away from each other as a wire is being inserted into the connector. The prongs 24, because of their elasticity, tend to turn to their original position as soon as a wire has been inserted to a depth immediately below their 15 free ends 26 as shown in Figure 4. Each of the sidewalls 18 has a generally vertical slot 28 on the innerfacethereof. In addition, each interiorwall 20 is provided with a generally vertical slot 28 on each face, each pair of opposed vertical slots defining a 20 guide channel. Each guide channel extends downwardly from the upper edges 22 of the side and interior walls to an intermediate termination point 30. A terminal can then be mounted in the connector with its edges riding in the guide channel. It will be 25 appreciated by those skilled in the art that other methods may be employed for securing the terminal in the connector.

As shown in Figure 2, the housing 14 includes a pair of opposed lower end walls 32 which are joined 30 to sidewalls 18forming a lower elongate cavity 34. In the embodiment shown, elongate cavity 34 includes a peripheral edge 36 which defines one edge of a tapered opening 38 for receiving a terminal pin 12.

The housing 14 further includes a pair of opposed 35 webs 40 which are spaced from lower end walls 32 and which join sidewalls 18. The upper edges 42 of webs 40 are located above the upper edges 44 of lower end walls 32. As shown in Figure 1, upper edges 42 and 44 may be gently curved to define a 40 flattened "U" shape.

Housing 14 may be made of any suitable electrical-• ly insulating material such as a thermoplastic, e.g. unfilled polyester, which is generally injection moulded.

45 Figure 6 shows an individual terminal 16 particularly suited for use in the connector of the invention. The terminal 16 includes an IDC 46 having a pair of blades 48 defined by a line of cut 50. Optionally, a strain relief aperture 52 can be provided at the base 50 of cut 50. This aperture tends to prevent propagation of the of the cut beyond its intended limit. Ordinarily, the ends of blades 48 are tapered inwardly as shown defining a "V" shaped entryway 54 which guides the entry of a wire.

55 The edges of IDC 46 can be tapered outwardly and shaped to ride in the guide channel formed by slots 28. The lower portion of terminal 16 comprises a beam 56 which is integrally joined to IDC 46 and shaped and relieved to conform to the inner con-60 tours of the connector housing. Alternatively, beam 56, an elongate strip of sheet metal, may be formed into other shapes for mating with various electrical devices such as substrates, boards and pins.

The terminals 16 may be stamped or cut from any 65 suitable strip conducting material, such as phosphor/bronze or other copper alloy. Preferably, the terminals are formed from spring tempered strip material having a thickness of about .008 to .025 inch (0.203 to 0.635 mm). It will be appreciated by those 70 skilled in the art that the line of cut will open up generally parabolically as a wire is inserted. However, the IDC may be prestressed, i.e., the line of cut may be opened slightly in the die during the stamping operation, before it is mounted in the 75 connector.

In operation, a wire to be terminated is located in the tapered access to the connector as shown in Figure 3. A suitable insertion tool 60 is employed to move the wire into the connector, flexibly displacing 80 prongs 24. The termination is accomplished as wire 11 is inserted in the connectorto a depth just below the free ends 26 of prongs 24 and blades 48 cut the insulation and positively contact the wire's conductor. After a wire has been terminated, prongs 24 tend 85 to return to their initial position so that free ends 26 rest against the upper surface of the wire's insulation.

It is known and appreciated by those skilled in the art that motion of a terminated wire relative to the 90 IDC must be prevented to achieve a reliable connection. The flexible prongs 24 prevent a terminated wire from moving upwardly out of the connector while at the same time the upper edges 44 of the lower end walls 32 prevent the wire from being 95 moved downwardly into the connector any farther than is necessary for the conductor to reliably contact blades 48.

One of the most important features of this invention is that it provides the capability of successfully 100 terminating wires varying greatly in size, for example, wires ranging from 22 awg to 30 awg on 0.100 in centres and from 18 awg to 28 awg on 0.156 inch centres. Wires can be terminated according to the following procedure:

105 All wires to be terminated, regardless of size, are inserted into the connector using the sametool, which simply pushes the wire down until its top surface is just below the trailing edges 26 of prongs 24.

110 As seen in Figures 4 and 4a, a conductor of a larger wire is automatically pushed further down into wire slot 50 than the conductor of a smaller wire.

Figure 7 is a schematic representation of the interrelationship between the force deformation 115 curves for the family of wires of interest and the force displacement curves of the IDC. The places where a wire and an IDC curve intersect are points of equilibrium between wire and the IDC. This type of representation of IDC versus wire is well known to 120 those familiar with the IDC art.

Because of space and cost considerations, the IDC's which are suitable for use in this invention are relatively small, e.g., usually only about 0.100 to 0.200 inches long (2.5 to 5.0 mm). Such small IDC's 125 tend to exhibit a large amount of plastic deformation when their displacement is relatively large and their stiffness is relatively high.

This is exactly what happens when a large wire (large displacement) is pushed relatively deep into 130 the IDC line of cut (high stiffness). Figure 7 illustrates

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GB 2 089 147 A

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this behaviour of the larger wire terminated to the IDC. The equilibrium between IDC and wire falls within the satisfactory range of wire deformation. The high initial stiffness is achieved by the wire 5 being placed relatively deep in the slot formed between blades 48 and the large amount of plastic deformation in the IDC results from the high displacement caused by the larger diameter wire.

Figure 7 shows that the IDC behaviour when 10 terminating smaller wire is markedly different when the larger wire is terminated. The IDC stiffness is lower because the wire is placed relatively less deep into the line of cut, and little or no plastic deformation occurs in the IDC because of the small displace-15 ment caused by the smaller diameter wire. Again, however, the equilibrium between IDC and wire falls within the range of satisfactory wire deformation.

The connector system performance for intermediate size wires is also quite satisfactory. In a typical 20 0.100 inch centre connector, the large wire would be about 22 awg and the small wire would be about 30 awg.

In a preferred embodiment of this invention the width of the guide channel in which the IDC rides is 25 no more than twice the thickness of the terminal, and preferably no more than 1.5 times the terminal thickness. The blades of the IDC are thus restrained and prevented from skewing.

Referring now to Figures 2 and 5 there is shown 30 another important feature of this invention. Figure 2 illustrates a wire having been terminated at its end. Figure 5 illustrates a wire terminated mid-span. The upper edge 42 of web 40 co-operates with the trailing edge 26 of prong 24 to impart an "S" bend in 35 a wire as it is terminated. The "S" bend is an important strain relief feature which practically eliminates movement of the wire conductor relative to the IDC.

Claims

40 CLAIMS

1. An electrical connector comprising a housing having a pair of opposed sidewalls, each of which has at least one prong integrally joined thereto

45 adjacent the upper edge thereof, the prongs extending inwardly in opposed relationship to define a tapered access for a discrete wire; a pair of opposed lower end walls joined to said sidewalls forming a lower elongate cavity; a pair of opposed webs 50 spaced from said endwalls joining said sidewalls and having upper edges above the upper edges of said lower end wails; and a terminal, including an insulation displacement contact having a pair of blades defined by a line of cut, mounted between 55 said sidewalls in parallel spaced relation to said webs, said blades being arranged to receive and terminate a wire inserted therebetween.

2. An electric connector as claimed in claim 1, in which each of said sidewalls has a slot on the inner

60 face thereof, the slots being opposed to provide a generally vertical guide channel extending downwardly from the upper edges of the sidewalls; and the outer edges of said contact ride in said guide channel.

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3. An electrical connector as claimed in claim 1

or 2, wherein the terminal has a strain relief aperture at the base of said cut.

4. An electrical connector as claimed in any preceding claim, comprising a tapered opening to

70 allow a terminal pin to enter the lower elongate cavity, and said terminal includes a beam integrally joined to said insulation displacement contact and extending downwardly therefrom into the lower elongate cavity for contacting the terminal pin.

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5. An electrical connector as claimed in any preceding claim, in which the ends of said blades are tapered inwardly defining a "V" shaped entry to said cut.

6. An electrical connector as claimed in any

80 preceding claim, wherein each of said prongs has a free end adapted to rest against the surface of a terminated wire.

7. An electrical connector as claimed in claim 6, wherein the free ends of the prongs are substantially

85 level with or below the upper surfaces of said opposed webs.

8. An electrical connector comprising a housing having a pair of opposed sidewalls and at least one interior wall spaced from and parallel to said side-

90 walls to define a plurality of discrete cavities; each of said sidewalls and the or each interior wall having at least one prong integrally joined thereto against the upper edge thereof on each face adjacent one of said cavities, the prongs extending inwardly into said

95 discrete cavities in opposed relationship to define a tapered access thereinto for a discrete wire; a pair of opposed lower end walls joined to said sidewalls and the or each interior wall to form a plurality of lower elongate cavities; a pair of opposed webs 100 spaced from said endwalls joining said sidewalls and the or each interior wall having upper edges above the upper edges of said lower end walls; and a terminal located in each of the said cavities, each said terminal including an insulation displacement 105 contact having a pair of blades defined by a line of cut.

9. An electrical connector as claimed in claim 8, wherein each of said sidewalls has a generally vertical slot on the inner face thereof extending

110 downwardly from the upper edge thereof, the or each interior wall has a generally vertical slot on each face thereof extending downwardly from the upper edge thereof in opposed spaced relation to the slot on the opposite surface of the cavity to provide a 115 guide channel in each cavity; and the outer edges of each contact ride in a respective guide channel.

10. An electrical connector as claimed in claim 8 or 9, wherein each of said prongs has a free end adapted to rest against the surface of a terminated

120 wire.

11. An electrical connector as claimed in claim 10, wherein the free ends of the prongs are substantially level with or below the upper surfaces of said opposed webs.

125

12. An electrical connector, substantially as herein described with reference to the accompanying drawings.

Printed for Her Majesty's Stationery Office, by Croydon Printing Company Limited, Croydon, Surrey, 1982.

Published by The Patent Office, 25 Southampton Buildings, London,

WC2A1AY, from which copies may be obtained.