GB1584150A

GB1584150A - Electrical components and a method of packaging them

Info

Publication number: GB1584150A
Application number: GB3855676A
Authority: GB
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1977-09-16
Filing date: 1977-09-16
Publication date: 1981-02-04

Description

(54) IMPROVEMENTS IN OR RELATING TO ELECTRICAL COMPONENTS AND A METHOD OF PACKAGING THEM (71) We, THE GENERAL ELECTRIC COMPANY LIMITED, of 1 Stanhope Gate, London W1A 1EH., a British Company, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to electrical components, particularly of the kind having terminal connections provided by wires, and to methods of packaging them.

The packaging of electrical components is important in the field of printed circuit board assemblies for example. In such a case a component with terminal wires is required to have them parallel and spaced apart a predetermined distance. The wires can then be inserted through holes in the printed circuit board to facilitate soldering thereto.

When components, capacitors, for example, are made initially, their terminal wires may be fitted without reference to any final positioning on a printed circuit board or other final situation. The wires then have to be bent to conform to the final positioning requirements such as mentioned above. Once formed, the wire connections may be encapsulated, together with the component, in potting resin to prevent damage in transport or assembly and to make permanent the relative disposition of the wires.

However, before the component is finally potted, or otherwise packaged permanently, the junctions of the wires and the component itself are liable to damage, especially in the course of bending the wires into their parallel disposition. This is particularly important in the case of extended-foil type capacitors where the quality of the component suffers if the wire connection is in any way damaged.

An object of the present invention is therefore to provide a component and a method of packaging it which obviate to a large extent the possibility of damage to the junction of the wire terminal connection and the component.

According to one aspect of the present invention therefore, a method of forming an electrical component having a terminal wire, includes the step of providing a local weakness in the wire to relieve any stress that may be imposed on the junction of the wire and the component by bending the wire.

The local weakness is preferably provided at a location in the wire close to the junction, and may be provided before or after the terminal wire connection has been made to the component.

According to another aspect of the in vention, a method of packaging an electrical component having terminal wire connections includes the steps of providing such a component with a local weakness in at least one wire, bending each wire so weakened at its respective weak location into approximate parallelism with the or another wire, and inserting the wires into guide ways in a supporting member, each said local weakness being strained by any misalignment of the parallel wires with said guide ways and thereby relieving any stress that may otherwise be imposed on the junctions of the wires and the component.

The guide ways may comprise holes in the member, which may be a box, the holes then being in the closed end of the box.

Alternatively, or in addition, the guide ways may comprise two substantially parallel channels open towards each other.

Where the member is a box, the channels are preferably provided in the walls of the box, their lengths extending perpendicular to an open end of the box. In a refinement of this method, each wire with a local weakness is bent at said local weakness so that the wires diverge very slightly from the component and provide a very slight spring retaining force when inserted into said channels.

According to further aspects, the invention consists in an electrical component adapted for packaging as aforesaid, or a component so packaged.

A method of forming and packaging an electrical component with a terminal wire con nection, and a component so formed and packaged, will now be described, by way of example, with reference to the accompanying drawings, of which: Figure 1 is a perspective view of a packaged wound extended-foil capacitor with terminal wire connections; Figure 2 is a side elevation of such a capacitor in accordance with the prior art; Figure 3 is a side elevation of a capacitor formed in accordance with the present in Vention; and Figure 4 is a side elevation of the capacitor of Figure 3 with terminal wires bent ready for packaging.

Referring to the drawings, Figure 2 shows a conventional wound extended foil capacitor its axis being vertical in the drawing. The capacitor consists of two layers of foil insulated from each other and wound into a cylinder in known manner. One layer protrudes slightly at one end and the other layer at the other end, hence the "extended foil" designation. Terminal wires 1 and 2 are attached to the respective foil layers by welding or other means. However, because of the fragile nature of the foil, the junctions between the wires 1 and 2 and the foil layers are correspondingly fragile.

The wires 1 and 2 are required to be bent parallel to each other, or approximately so, at a spacing determined by the physical layout of the circuit in which the capacitor is to be connected. In the case of a printed circuit board it is the spacing of the holes which are to receive the wires which determines the spacing of the wires. Since the wire spacing is critical, therefore, it may be desirable to bend them after they have been connected to the foil layers, as shown in Figure 2. This does mean, however, that some stress is likely to be imposed on the junction of the wire and the foil in bending the wire. Even where the wires are bent before attachment to the capacitor, however, handling or packaging of the capacitor and wires may impose stresses on the junction.

Figure 3 shows how this stress may be relieved in accordance with the invention.

Close to the junction of each wire 1 and 2 and the capacitor body 3 a local weakness 6 is imposed by reducing the cross section of the wire in a direction transverse to the bending axis. This reduction may be imposed by squeezing or crimping the wire locally, or by actual removal of the material of the wire on one or both sides. In the former case work-hardening may occur and tempering may have to be employed.

Having provided a component in the form of Figure 3 and bent the wire terminals as shown in Figure 4, it will then generally be necessary to package it for ease of hand ling and to maintain the spacing of the wires.

For this purpose the component is housed in an open ended box 5 such as shown in Figure 1. The box may have guide ways (the ends of which, 4, are shown in Figure 1.) These guide ways are channels open towards each other, extending perpendicular to the open end, and moulded integrally in the corners of the box. The spacing of the diagonally opposite guide ways conforms to the spacing of the wires 1 and 2 of a com ponent such as that shown in Figure 4. This component is then inserted head first into the box 5 with the wires 1 and 2 located within the channels.

If the wires are spaced slightly too far apart they are forced together by the guide ways 4 as they enter the box 5. In the absence of the local weaknesses 6, such forcing to gether of the wires 1 and 2 might impose excessive stress on the junction of the wire and the component and damage it. The local weaknesses 6 do, on the other hand, absorb most of the stress. In addition, in the absence of the imposed weaknesses 6 the bent wires, if not accurately spaced, may distort the box 5 making it conform to the wire spacing rather than vice versa. The final wire spacing is then wrong.

In an alternative arrangement the closed end of the box has guidways in the form of holes spaced apart the appropriate distance for the wires and the component is inserted wires first, the wires entering the holes.

Again in this case, if the wire spacing does not conform exactly to the hole spacing undue stress would be put on the junctions of the wires and component in the absence of the local weaknesses 6.

In a modification of the latter arrangement the box includes channels as well as holes and the component is inserted wires first, the wires entering the channels and then the holes at the end of the channels.

The packaging is then completed by filling the box with a potting compound.

Clearly the invention is applicable to cap acitors of other design and also to components other than capacitors.

The invention may be seen to consist in the provision of a component with locally weakened terminal wire connections, or in the component package employing such a component.

It will also be clear that it is not essential for both wires to be weakened as described.

In some components it may be desirable to have one very rigid terminal firmly secured to the component and one wire terminal weakened to take all the strain that may arise as described above.

Clearly some components may have more than two terminal wires and all of them may be weakened as described.

WHAT WE CLAIM IS:- 1. A method of forming an electrical component having a terminal wire, including the step of providing a local weakness in the wire to relieve any stress that may be imposed on the junction of the wire and the component by bending the wire.

2. A method according to Claim 1, where in said local weakness is provided at a location in the wire close to said junction.

3. A method according to Claim 1 or Claim 2 wherein said local weakness is provided after the terminal wire connection has been made to the component.

4. A method of packaging an electrical component having terminal wire connections including the steps of providing such a component with a local weakness in at least one wire, bending each wire so weakened at its respective weak location into approximate parallelism with the or another wire, and inserting the wires into guide ways in a supporting member, each said local weakness being strained by any misalignment of the parallel wires with said guide ways and thereby relieving any stress that may otherwise be imposed on the junctions of the wires and the component.

5. A method according to Claim 4, wherein each said local weakness is provided at a location in the wire close to the component.

6. A method according to Claim 4 or Claim 5, wherein said guide ways comprise holes in said member.

7. A method according to Claim 6 wherein said member is a box and said holes are in the closed end of the box.

8. A method according to Claim 4 or Claim 5, wherein said guide ways comprise two substantially parallel channels open towards each other.

9. A method according to Claim 8, wherein said member is a box and said channels are provided in the walls of the box, their lengths extending perpendicular to an open end of the box.

10. A method according to Claim 8 or Claim 9 wherein each wire with a local weakness is bent at said local weakness so that the wires diverge very slightly from the component and provide a very slight spring retaining force when inserted into said channels.

11. An electrical component manufactured in accordance with the method of any of

Claims

Claims 1-3.

12. An electrical component packaged in accordance with the method of any of Claims 4-10.

13. A method of manufacturing an electrical component with terminal wire connections, substantially as hereinbefore described with reference to Figures 1, 3 and 4 of the accompanying drawings.

14. A method of packaging an electrical component with terminal wire connections, substantially as hereinbefore described with reference to Figures 1, 3 and 4 of the accompanying drawings.