GB1579246A

GB1579246A - Electrical componentss

Info

Publication number: GB1579246A
Application number: GB1886777A
Authority: GB
Original assignee: Standard Telephone and Cables PLC
Current assignee: STC PLC
Priority date: 1977-05-05
Filing date: 1977-05-05
Publication date: 1980-11-19
Also published as: DE2816673C2; BR7802820A; DE2816673A1

Description

(54) IMPROVEMENTS IN AND RELATING TO ELECTRICAL COMPONENTS (71) We, STANDARD TELEPHONES AND CABLES LIMITED, a British Company, of 190 Strand, London W.C.2, England, 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 but not exclusively capacitors.

We currently manufacture solid tantalum capacitors as shown generally for example in Figure 1 of the accompanying drawing, which is a schematic cross-section of a tantalum capacitor, as described for example in British Patent Specification No. 1,055,751.

In Figure 1 the solid tantalum capacitor anode body 1 is of generally cylindrical shape and has an anode lead 2 extending axially from it. The body is coated with a dielectric layer, an electrolyte layer and a cathode layer none of which is shown in detail. Two terminations are provided, a positive termination 3 in the form of a double cranked lead wire and a negative termination 5 in the form of a cranked wire.

The wire 3 is connected to the wire 2 by a welded joint 4 and the lead wire 5 is soldered (not shown) to the cathode layer.

The whole is encapsulated in resin 6 as indicated by the dashed line.

As can be seen in this particular example a portion 7 of the tantalum anode wire 2 projects through the covering surface of the resin 6. Normally this capacitor would be rejected as unsatisfactory in view of the projecting portion 7.

Preferably the projection 7 is not more than a millimetre or so beyond the cranked limb of the wire 3. Under these circumstances the projecting portion 7 will not project through the subsequently-applied resin and the capacitor will be satisfactory. Alternatively it is possible, in a case such as is illustrated in Figure 1, to apply a larger amount of resin in the region of the terminals to ensure that the portion 7 does not eventually project through the resin. It would also be possible to cut off the projecting portion 7 before applying the resin but this is a tricky procedure.

According to the present invention there is provided an electrical component comprising a body having a first electrical connection member projecting away from the body, a second electrical connection member connected to the body at a position spaced from the first member, a third electrical connection member joined to the first member ahd extending away from the body in the same general direction as the second member, wherein the third member crosses the first member at the joint between the two, the free end portion of the first member having been bent towards the third member after being joined thereto, the body, the joint and the said free end portion being encapsulated in insulating material.

According to a further aspect of the present invention there is provided a method of testing an electrical component comprising a body having a first electrical connection member projecting away from the body, a second electrical connection member joined to the body at a position spaced from the first member, and a third electrical connection member joined to the first member so that it crosses the first member at the joint between the two and extends parallel to and in the same direction as the second member, which method includes the step of causing relative movement between a test member and the first member to test if the free end portion of the first member- projects more than a predetermined distance from the joint, and wherein if such a projecting portion exists the test member and the relative movement serve also to push the free end portion of the first member over towards the third member and encapsulating the body, joint and free end portion in insulating material by a dipping technique.

In order that the invention can be clearly understood reference will now be made to the remainder of the drawings, in which: Figure 2 shows somewhat schematically a solid electrolytic tantalum capacitor according to an embodiment of the present invention.

Figure 3 shows schematically one step in the testing and manufacture of the capacitor of Figure 2 and Figure 4 shows the region of the joint in greater detail.

Referring to Figure 2 an electrical component in the form of a solid electrolytic tantalum capacitor has an anode body 1' with an anode wire 2' projecting away from the body and forming an electrical connection member. On the surface of the body 1' a- cathode layer (not shown) is formed and a connection wire 5' forming a second electrical connection member -is connected to the cathode layer by means of solder (not shown) or other suitable connection material.

This forms cathode connection and is spaced from the anode connection. A third electrical connection member in the form of a connection wire 3' is joined to the anode wire 2' by means of a weld at 4' where the end portions of wires 2' and 3' cross one another.

When the weld has been formed the projecting portion 8 of the anode 2' is bent towards the wire 3' so as to lay along the end portion of 3' and slightly across it, as shown in greater detail in Figure 4.

Subsequently the body and parts of the leads are encapsulated in resin 6' so as to completely cover the joint 4' and the bent end portion 8.

Referring to Figure 3 this shows one stage in the manufacture of the capacitor shown in Figure 2 in which the cranked wire 3' is held in a clamp 9 at a welding station (not shown in greater detail). The body 1' with its tantalum anode wire 2' is held in a jig 122 so that the anode wire 2' crosses the end portion 3" of the wire 3'. A pair of welding tools 10 and 11 form the weld 4' between the tantalum wire and the end portion 3" of the solder coated terminal wire 3'.

While the body 1' and wire 3' are still held a pusher 12 moves from the first position 12' to the second position 12" where it bends the projecting end portion 8 of the tantalum wire 2' towards the wire 3" to lie along it and slightly across it as shown in greater detail in Figure 4.

Although not shown, it would be possible for the cathode connection wire 5' to have already been connected to the cathode layer on the body 1' and before the welding and bending operation and this wire could, with advantage, be used to locate the body 1' during the welding and bending operations.

Encapsulation in the resin 6' can be conveniently accomplished by dipping the body with its wires connected down into a bath of resin and allowing the coating of resin to dry in a heated atmosphere.

It is important to note that the dimensions of the capacitor body, anode wire and connection wires are normally arranged so that the distance by which the free end portion of the anode wire extends beyond the welded joint should be about lmm.

Because of tolerances and handling errors it sometimes happens, however, that this distance is larger than Imm., in which case the existence of the excess projection must be detected and any projecting portion bent over so that capacitors according to Figure -2 of the drawing are formed which can nevertheless be accepted as satisfactory. Furthermore, regardless of the length of the projecting portion, it is envisaged that all capacitors will pass through the welding station equipped with the pushing member, but this member will only act on those projecting portions which project far enough to be engaged by it and therefore acts also as a testing member.

Thus, referring to Figure 4 of the drawing, the distance d between the bottom of the pushing and test member 12 and the top of the end 3" of the wire 3' is arranged to be fractionally larger than lmm. preferably 1 5mum.

As shown in Figure 3 the welding electrode 10 can be used as a reaction surface to resist the action of the member 12 in those cases where the projecting end portion is to be bent. However, it would be possible to retract the welding electrode 10 and move in a reaction member (not shown) instead.

Alternatively, it would be possible to arrange the clamp 9 to hold the wire j much closer to the weld, for example to hold the portion 3", so that the clamp 9 by itself can provide the necessary support and reaction.

Whilst movement of the test and pushing member 12 towards the first member (wire 2') has been described, it would alternatively be possible to produce the same result by moving the wire 2' etc. towards the member 12, or otherwise cause relative movement between them.

WHAT WE CLAIM IS: 1. An electrical component comprising a body having a first electrical connection member projecting away from the body, a second electrical connection member connected to the body at a position spaced from the first member, a third electrical connection member joined to the first member and extending away from the body in the same general direction as the second member, wherein the third member crosses the first member at the joint between the two, the free end portion of the first member having been bent towards the third member after being joined thereto, the body, the joint and the bent free end portion being encapsulated in insulating material.

2. An electrical component according to claim 1 in the form of a solid electrolytic capacitor.

3. A method of testing an electrical component comprising a body having a first

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Figure 3 shows schematically one step in the testing and manufacture of the capacitor of Figure 2 and Figure 4 shows the region of the joint in greater detail. Referring to Figure 2 an electrical component in the form of a solid electrolytic tantalum capacitor has an anode body 1' with an anode wire 2' projecting away from the body and forming an electrical connection member. On the surface of the body 1' a- cathode layer (not shown) is formed and a connection wire 5' forming a second electrical connection member -is connected to the cathode layer by means of solder (not shown) or other suitable connection material. This forms cathode connection and is spaced from the anode connection. A third electrical connection member in the form of a connection wire 3' is joined to the anode wire 2' by means of a weld at 4' where the end portions of wires 2' and 3' cross one another. When the weld has been formed the projecting portion 8 of the anode 2' is bent towards the wire 3' so as to lay along the end portion of 3' and slightly across it, as shown in greater detail in Figure 4. Subsequently the body and parts of the leads are encapsulated in resin 6' so as to completely cover the joint 4' and the bent end portion 8. Referring to Figure 3 this shows one stage in the manufacture of the capacitor shown in Figure 2 in which the cranked wire 3' is held in a clamp 9 at a welding station (not shown in greater detail). The body 1' with its tantalum anode wire 2' is held in a jig 122 so that the anode wire 2' crosses the end portion 3" of the wire 3'. A pair of welding tools 10 and 11 form the weld 4' between the tantalum wire and the end portion 3" of the solder coated terminal wire 3'. While the body 1' and wire 3' are still held a pusher 12 moves from the first position 12' to the second position 12" where it bends the projecting end portion 8 of the tantalum wire 2' towards the wire 3" to lie along it and slightly across it as shown in greater detail in Figure 4. Although not shown, it would be possible for the cathode connection wire 5' to have already been connected to the cathode layer on the body 1' and before the welding and bending operation and this wire could, with advantage, be used to locate the body 1' during the welding and bending operations. Encapsulation in the resin 6' can be conveniently accomplished by dipping the body with its wires connected down into a bath of resin and allowing the coating of resin to dry in a heated atmosphere. It is important to note that the dimensions of the capacitor body, anode wire and connection wires are normally arranged so that the distance by which the free end portion of the anode wire extends beyond the welded joint should be about lmm. Because of tolerances and handling errors it sometimes happens, however, that this distance is larger than Imm., in which case the existence of the excess projection must be detected and any projecting portion bent over so that capacitors according to Figure -2 of the drawing are formed which can nevertheless be accepted as satisfactory. Furthermore, regardless of the length of the projecting portion, it is envisaged that all capacitors will pass through the welding station equipped with the pushing member, but this member will only act on those projecting portions which project far enough to be engaged by it and therefore acts also as a testing member. Thus, referring to Figure 4 of the drawing, the distance d between the bottom of the pushing and test member 12 and the top of the end 3" of the wire 3' is arranged to be fractionally larger than lmm. preferably 1 5mum. As shown in Figure 3 the welding electrode 10 can be used as a reaction surface to resist the action of the member 12 in those cases where the projecting end portion is to be bent. However, it would be possible to retract the welding electrode 10 and move in a reaction member (not shown) instead. Alternatively, it would be possible to arrange the clamp 9 to hold the wire j much closer to the weld, for example to hold the portion 3", so that the clamp 9 by itself can provide the necessary support and reaction. Whilst movement of the test and pushing member 12 towards the first member (wire 2') has been described, it would alternatively be possible to produce the same result by moving the wire 2' etc. towards the member 12, or otherwise cause relative movement between them. WHAT WE CLAIM IS:

1. An electrical component comprising a body having a first electrical connection member projecting away from the body, a second electrical connection member connected to the body at a position spaced from the first member, a third electrical connection member joined to the first member and extending away from the body in the same general direction as the second member, wherein the third member crosses the first member at the joint between the two, the free end portion of the first member having been bent towards the third member after being joined thereto, the body, the joint and the bent free end portion being encapsulated in insulating material.

3. A method of testing an electrical component comprising a body having a first

electrical connection member projecting away from the body, a second electrical connection member joined to the body at a position spaced from the first member, and a third electrical connection member joined to the first member so that it crosses the first member at the joint between the two and extends parallel to and in the same direction as the second member, which method includes the step of causing relative movement between a test member and the first member to test if the free end portion of the first member projects more than a predetermined distance from the joint, and wherein if such a projecting portion exists the test member and the relative movement serve also to push the free end portion of the first member over towards the third member, and encapsulating the body, the joint and the free end portion in insulating material by a dipping technique.

4. A method according to claim 3 wherein the joint is formed by welding.

5. A method according to claim 3 or 4 wherein the joint is formed by welding and the third member is held during the welding operation, and wherein the test member and the relative movement serve to test for the projecting free end portion before the third member is released.

6. A capacitor substantially as hereinbefore described with reference to Figure 2 of the accompanying drawing.

7. A method of testing a capacitor substantially as hereinbefore described with reference to Figure 2, Figure 3 and Figure 4 of the accompanying drawing.