Double Thickness P.c.b. Flag Terminal

Abstract

A unitary electrical terminal made from sheet material for a printed circuit board edge connector, comprising a contact part including a base member of a channel section and double thickness, sides of the channel being extended at one end of the base member to define a pair of resilient, parallel spaced contact arms for receiving between an edge of a printed circuit board, each arm being of double thickness, the thickness of each contact arm being formed at the free end of the contact arm remote from the base member.

Description

The present invention relates to electrical terminals for printed circuit board edge connectors.

Known printed circuit board edge connector terminals have a contact part including a pair of resilient spaced arms for receiving an edge of a printed circuit board between them.

The thickness of a printed circuit board can vary between relatively wide manufacturing tolerances and it is desirable that the arms of the contact part of an electrical terminal exert a sufficiently high contact force on the printed circuit board to obtain a good electrical contact for the minimum of deflection, that is, when the thickness of the printed circuit board is at or near its lower limit of tolerance and yet are not strained beyond their elastic limit when receiving a printed circuit board having a thickness at or near the upper limit of the manufacturing tolerance.

The contact force exerted by an arm for a given deflection can be increased by increasing the thickness of the arm. However, when the terminal is formed from sheet material and where a connector part of the terminal is in the form of a ferrule intended for crimping to a conductor wire, the increased thickness of the ferrule often produces difficulties when forming a satisfactory crimped connection.

In order to overcome this disadvantage, it has been known to mill part of the sheet material from which the terminal is to be formed so that the sheet material has, in effect, two thicknesses the contact part being formed from the greater thickness and the connector part from the lesser thickness. This milling operation is expensive and wasteful of material.

Another known method by which this disadvantage has been overcome is by positioning the arms of the contact part of a terminal between strengthening plates of a similar configuration to the arms.

However, this requires the careful forming of the strengthening plates with a consequent increase in the cost of manufacture of the electrical terminal.

According to the present invention, a unitary electrical terminal made from sheet material for a printed circuit board edge connector comprises a unitary electrical terminal made from sheet material for a printed circuit board edge connector, comprising a contact part including a base member of channel section and double thickness, sides of the channel being extended at one end of the base member axially of the base member to define a pair of resilient, parallel spaced contact arms for receiving between them an edge of a printed circuit board, each contact arm being of double thickness, the thicknesses of each contact arm being integrally formed at the free end of the contact arm remote from the base member.

In a preferred embodiment, a transition part extends transversely from one end of a connector part of the electrical terminal and interconnects the connector part to an edge of the base member of the contact part, to give the electrical terminal a generally flag configuration.

An embodiment of the invention will now be described by way of example, reference being made to the Figures of the accompanying drawings, in which:

FIG. 1 is a plan view of an electrical terminal crimped to one end of a conductor wire:

FIG. 2 is a cross-section on the line II--II of FIG. 1:

FIG. 3 is a perspective view of a printed circuit board edge connector and a printed circuit board shown in ghosted lines assembled to the edge connector;

FIG. 4 is a view of the underside of the edge connector of FIG. 3 assembled to a support plate for the printed circuit board; and

FIG. 5 is a cross-section on the line V--V of FIG. 3.

As shown in FIGS. 1 and 2, an electrical terminal 1 formed as a unitary structure from a single piece of electrically conductive sheet material, for example, brass, comprises a connector part 3 for connection to a conductor wire 5 and a contact part 7.

The connector part 3 includes two pairs of arms 9, 11 which define, before crimping, two open U-shaped ferrules. As shown, the ferrules are crimped respectively to the conductive core 13 and outer insulating sleeve 15 of the wire 5.

A transition part 17 extends transversely from one end 18 of the connector part 3 and interconnects the connector part 3 to one edge 39 of a base member 25 of the contact part 7.

The contact part 7 includes the base member 25 which is of channel section and double thickness. Sides of the channel are extended at one end of the base member 25 axially of the base member to define a pair of spaced, parallel, elongate contact arms 19, 21. The arms 19, 21 are of double thickness and the thicknesses of each arm are interconnected at the free end 10 of the arm remote from the base member 25. The inner thickness of the double thickness of sheet material of each contact arm 19, 21 so formed, is separated from the corresponding outer thickness, adjacent the free end 10 of the arm, to form a protuberance 31, 33. The opposed faces of the protuberances 31, 33 define contact surfaces for resiliently contacting the opposite surfaces of a printed circuit board when positioned between the arms 19, 21. The contact surfaces are embossed as indicated at 35.

The transition portion 17 is connected to the edge 39 of the base member 25 and a resilient locking lance 32 extends from the opposite edge 41 of the base member 25 and, as shown in FIG. 2, is folded over on itself to extend upwardly between the arms 19, 21 generally towards the connector part 3 of the terminal 1.

The arms contact 19, 21 taper from a wider end adjacent the base member 25 to their narrower free ends 10.

Referring now to FIGS. 3, 4 and 5 a plurality of terminals 1 are assembled in an insulated housing 51. The housing 51 is generally L-shaped in transverse cross-section. Each terminal 1 is received in a passageway 53 separated from adjacent passageways 53 by side walls 55. Each passageway 53 has a first portion 57 in which the contact part 7 of the terminal 1 is received and a second portion 59 in which the connector part 3 is received. The portion 59 has its lower (as seen in FIG. 5) side open in order that a terminal 1 can be assembled in its respective passageway 53. The first portion 57 has a part 63 of reduced cross-section which engages the contact part 7 adjacent the base member 25 to minimise movement of the terminal 1 in the passageway should a force be applied to a wire 5 in the direction of arrow N, and a part 65 of greater cross-section adjacent the arms 19, 21 which permits flexure of the arms. The arms 19, 21 extend on opposite sides of a slot 64 formed in the side walls 55 for receiving a printed circuit board.

On the rear surface 50 of the housing 51, adjacent each end, there is arranged a pair of spaced, parallel rails 81, 83 generally of a hook-shape in transverse cross-section. Intermediate the rails 81, 83 is positioned a resilient arm 85 which is connected to the housing 51 adjacent the upper side of the housing. The resilient arm 85 depends downwardly from the upper side and carries a proturberance 87.

As shown in the FIGS. 4 and 5, a printed circuit board 70 shown in ghosted lines, is mounted on a support plate 71. The support plate 71 is formed with a recess 73 having two spaced parallel hooks 75, 77 and an indentation 79 arranged centrally of the hooks 75, 77.

When the edge connector is assembled to the support plate 71, the rails 81, 83 of the housing 51 engage under the hooks 75, 77 in the recess 73 of the support plate 71 so that any pull on a wire 5 in the direction of arrow P will be transmitted to the support plate 71 and will not be transmitted to the printed circuit board 70. Further, the protuberance 87 resiliently engages in the indentation 79 to lock the housing 51 against vertical movement as seen in the Figures, relative to the support plate 71. An arcuate recess (not shown) is formed in the support plate 71 which permits the flexible arm to be depressed when it is required to remove the housing 51 from the support plate 71.

Claims

1. A unitary electrical terminal made from sheet material for a printed circuit board edge connector, comprising a contact part including a base member of channel section and double thickness, each side of the channel being extended at one end of the base member in a direction parallel to the line of intersection of the side with the bottom of the channel to define a pair of resilient parallel spaced contact arms for receiving between them an edge of a printed circuit board, each contact arm being of double thickness, the thickness of each contact arm being integrally formed at the free end of the contact arm remote from the base member and being in touching relation throughout the major portion of said contact arms, and an integral ferrule portion of single thickness and connected by a transition part to an edge of the base member and of the contact part.

2. An electrical terminal as claimed in claim 1 in which the inner thickness of the double thickness of sheet material of each contact arm is separated from the complementary outer thickness adjacent the free end only to form a protuberance, the inner surfaces of the protuberances defining contact surfaces for electrical engagement with conductors of a printed circuit board when placed between the contact arms.