GB1577684A

GB1577684A - Fuse array

Info

Publication number: GB1577684A
Application number: GB5150777A
Authority: GB
Original assignee: Welwyn Electric Ltd
Current assignee: Welwyn Electric Ltd
Priority date: 1978-03-28
Filing date: 1978-03-28
Publication date: 1980-10-29

Description

(54) FUSE ARRAY (71) We, WELWYN ELECTRIC LIMITED of Bedlington, Northumberland NE22 7AA, 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 an electrical fuse array for the protection of electrical apparatus against the effects of electrical overload, or for programmably severing in order to control electrical apparatus. In particular, the invention relates to a miniature electrical fuse array comprising a plurality of links capable of being fused or severed upon passage therethrough, via terminal lead members, of a predetermined electric current or voltage, the array being suitable for mounting on and electrically connecting to conductors on a circuit board or wafer.

The invention also relates to a method of making an electrical fuse array.

According to the invention, an electrical fuse array is provided comprising (i) an electrically insulating housing consisting of a base having thereon an upstanding peripheral rim and within confines of said rim a plurality of upstanding wall mmebers disposed side by side on said base in spaced parallel relationship, said base, peripheral rim and wall members providing a plurality of elongate compartments in said housing; (ii) a plurality of pairs of electrically conductive terminal lead members secured to said housing and arranged whereby the lead members in a said pair extend into a said compartment from opposite ends thereof and such that ends of the lead members in each compartment are spaced apart, said peripheral rim being formed, at least where said lead members pass into each compartment, separately from said base, said rim, or separate portions thereof, being secured to said base, said lead members being arranged to pass into each compartment between, and be secured between, said rim and said base, and (iii) a plurality of electrically conductive links of fusible wire or tape, one said link being secured and electrically connected between the ends of each said pair of lead members in each said compartment of said housing.

Preferably said housing is formed of an organic plastics material.

Preferably said peripheral rim is secured to said base by means of an adhesive.

Said lead members are preferably provided in the form of flat tape.

Preferably said lead members are shaped in such a way that said array is capable of being mounted on a circuit board or wafer with said lead members secured and electrically connected to electrical conductors on said circuit board or wafer.

The said electrically conductive links of fusible wire or tape are suitably secured and electrically connected to said terminal lead members by welding, soldering or brazing.

Preferably the junctions between said links and said lead members are mechanically reinforced by application thereto of a cement or an organic resin material.

A preferred material is an epoxy resin.

If desired, the compartments containing the conductive links of fusible wire or tape may be filled with a suitable electrically insulating material.

A cover may also be provided for that face of the housing opposite the said base.

The invention is now described by way of example with reference to the accompanying drawing in which Figure 1 illustrates a perspective view of an embodiment of an electrical fuse array according to the invention and Figure 2 shows an exploded view of component parts utilised in the manufacture of the array of Figure 1.

Referring to Figure 1, an embodiment of a fuse array according to the invention comprises an electrically insulating housing of an organic plastics material such as glass filled nylon and consisting of a base 1 having an upstanding peripheral rim 2 secured thereto by means of an adhesive 3. A number of upstanding wall members 4 are provided on the base 1 within the confines of the rim 2 and these members 4 are disposed side by side in spaced parallel relationship. A number of compartments 5 are thereby provided in the housing. Pairs of flat electrically conductive lead members 6a and 6b are secured to the housing between the rim 2 and base 1, a separate pair of members 6a and 6b extending into each compartment 5. Lead members 6a and 6b are suitably formed of a nickelchromium alloy, e.g. Kovar (Registered Trade Mark).

An electrically conductive link in the form of a fusible wire 7, e.g. of a nickel chromium alloy, is secured and electrically connected to the ends of each pair of lead members, 6a, 6b, e.g. by welding. Each link 7 bridges the gap between the ends of the lead members 6a and 6b to which it is connected. A dot of an epoxy composition 8, e.g. composiion ER-155-16 supplied by Isochem Resins Co., Lincoln, R.I., U.S.A.

is applied to the area of each junction between the links 7 and their associated lead members 6a, 6b, to provide mechanical reinforcement for the connections. The lead members 6a, 6b are bent so that when the resulting fuse array is mounted with base 1 uppermost on a circuit board or wafer (not shown) lead members 6a, 6b can be electrically connected, e.g. by soldering, to electrical conductors on the circuit board or wafer.

The embodiment of Figure 1 is conveniently constructed as indicated in Figure 2. Referring to Figure 2, a base 1 for a housing is moulded from an organic plastics maerial, such as glass filled nylon and a number of upstanding wall members 4 are formed integrally with the base. A lead frame 6, constructed, for example, of nickel-chromium alloy, e.g. Kovar (Registered Trade Mark), is provided with a plurality of flat terminal lead members 6a, 6b thereon. Electrically conductive fuse links 7, suitably in the form of nickelchromium wire, are welded between the ends of lead members 6a and 6b and a dot 8 of an epoxy composition, e.g. ER-155-16 supplied by Isochem Resins Co., of the U.S.A., is applied to each welded joint to mechanically reinforce the joint.

A film of adhesive (not shown) is applied to the top edges of the base 1 and the lead frame 6 is located on the base so that the members 6a and 6b, with the fuse links attached, are disposed between the wall members 4. A peripheral rim member 2, also constructed from the same plastics material as the base, is then secured by the adhesive to the base 1, the lead frame 6 being sandwiched between the base 1 and rim 2. The lead frame 6 is then cut as indicated by dotted lines 9, to isolate the individual lead members 6a and 6b. These lead members are then bent to the shape shown in Figure 1 to enable the resulting array to be connected to conductors on a circuit board.

Referring again to Figure 1, if desired the compartments 5 may be filled with an electrically insulating material (not shown), such as a silicone resin, and a cover or lid (also not shown) may be provided on the remaining open side of the housing.

Each fuse in the array operates in known manner, i.e. when an electrical current or voltage in excess of a particular level is applied between a corresponding pair of lead members 6a, 6b, the fuse link 7 disintegrates. Because each fuse link is isolated from an adjacent similar link by being housed in an individual compartment, there is minimal risk of particles of a disintegrated fuse interfering with an adjacent sound fuse.

WHAT WE CLAIM IS:- 1. An electrical fuse array comprising: (i) an electrically insulating housing consisting of a base having thereon an upstanding peripheral rim and within confines of said rim a plurality of up standing wall members disposed side by side on said base in spaced parallel relationship, said base, peripheral rim and wall members providing a plurality of elongate compartments in said housing; (ii) a plurality of pairs of electrically conductive terminal lead members secured to said housing and arranged whereby the lead members in a said pair extend into a said compartment from opposite ends thereof and such that ends of the lead members in each said compartment are spaced apart, said peripheral rim being formed, at least where said lead members pass into each compartment, separately from said base. said rim, or separate portions thereof, being secured to said base, said lead members being arranged to pass into each compartment between

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. of a fuse array according to the invention comprises an electrically insulating housing of an organic plastics material such as glass filled nylon and consisting of a base 1 having an upstanding peripheral rim 2 secured thereto by means of an adhesive 3. A number of upstanding wall members 4 are provided on the base 1 within the confines of the rim 2 and these members 4 are disposed side by side in spaced parallel relationship. A number of compartments 5 are thereby provided in the housing. Pairs of flat electrically conductive lead members 6a and 6b are secured to the housing between the rim 2 and base 1, a separate pair of members 6a and 6b extending into each compartment 5. Lead members 6a and 6b are suitably formed of a nickelchromium alloy, e.g. Kovar (Registered Trade Mark). An electrically conductive link in the form of a fusible wire 7, e.g. of a nickel chromium alloy, is secured and electrically connected to the ends of each pair of lead members, 6a, 6b, e.g. by welding. Each link 7 bridges the gap between the ends of the lead members 6a and 6b to which it is connected. A dot of an epoxy composition 8, e.g. composiion ER-155-16 supplied by Isochem Resins Co., Lincoln, R.I., U.S.A. is applied to the area of each junction between the links 7 and their associated lead members 6a, 6b, to provide mechanical reinforcement for the connections. The lead members 6a, 6b are bent so that when the resulting fuse array is mounted with base 1 uppermost on a circuit board or wafer (not shown) lead members 6a, 6b can be electrically connected, e.g. by soldering, to electrical conductors on the circuit board or wafer. The embodiment of Figure 1 is conveniently constructed as indicated in Figure 2. Referring to Figure 2, a base 1 for a housing is moulded from an organic plastics maerial, such as glass filled nylon and a number of upstanding wall members 4 are formed integrally with the base. A lead frame 6, constructed, for example, of nickel-chromium alloy, e.g. Kovar (Registered Trade Mark), is provided with a plurality of flat terminal lead members 6a, 6b thereon. Electrically conductive fuse links 7, suitably in the form of nickelchromium wire, are welded between the ends of lead members 6a and 6b and a dot 8 of an epoxy composition, e.g. ER-155-16 supplied by Isochem Resins Co., of the U.S.A., is applied to each welded joint to mechanically reinforce the joint. A film of adhesive (not shown) is applied to the top edges of the base 1 and the lead frame 6 is located on the base so that the members 6a and 6b, with the fuse links attached, are disposed between the wall members 4. A peripheral rim member 2, also constructed from the same plastics material as the base, is then secured by the adhesive to the base 1, the lead frame 6 being sandwiched between the base 1 and rim 2. The lead frame 6 is then cut as indicated by dotted lines 9, to isolate the individual lead members 6a and 6b. These lead members are then bent to the shape shown in Figure 1 to enable the resulting array to be connected to conductors on a circuit board. Referring again to Figure 1, if desired the compartments 5 may be filled with an electrically insulating material (not shown), such as a silicone resin, and a cover or lid (also not shown) may be provided on the remaining open side of the housing. Each fuse in the array operates in known manner, i.e. when an electrical current or voltage in excess of a particular level is applied between a corresponding pair of lead members 6a, 6b, the fuse link 7 disintegrates. Because each fuse link is isolated from an adjacent similar link by being housed in an individual compartment, there is minimal risk of particles of a disintegrated fuse interfering with an adjacent sound fuse. WHAT WE CLAIM IS:-

1. An electrical fuse array comprising: (i) an electrically insulating housing consisting of a base having thereon an upstanding peripheral rim and within confines of said rim a plurality of up standing wall members disposed side by side on said base in spaced parallel relationship, said base, peripheral rim and wall members providing a plurality of elongate compartments in said housing; (ii) a plurality of pairs of electrically conductive terminal lead members secured to said housing and arranged whereby the lead members in a said pair extend into a said compartment from opposite ends thereof and such that ends of the lead members in each said compartment are spaced apart, said peripheral rim being formed, at least where said lead members pass into each compartment, separately from said base. said rim, or separate portions thereof, being secured to said base, said lead members being arranged to pass into each compartment between

and be secured between said rim and said base, and (iii) a plurality of electrically conduc tive links of fusible wire or tape, one said link being secured and electrically connected between the ends of each said pair of lead members in each said compartment of said housing.

2. A fuse array according to Claim 1 in which said housing is formed of an organic plasics material.

3. A fuse array according to Claim 1 or 2, in which said peripheral rim, or separate portions thereof, is or are secured to said base by means of an adhesive.

4. A fuse array according to Claim 1, 2 or 3, in which said lead members are provided in the form of flat tape.

5. A fuse array according to any one of the preceding Claims in which said lead members are shaped in such a way that said array is capable of being mounted on a circuit board or wafer with said lead members secured and electrically connected to electrical conductors on said circuit board or wafer.

6. A fuse array according to any one of the preceding Claims in which said electrically conductive links of fusible wire or tape are secured and electrically connected to said terminal lead members by welding, soldering or brazing.

7. A fuse array according to any one of the preceding Claims in which the junctions between said links and said lead members are mechanically reinforced by application thereto of a cement or an organic resin material.

8. A fuse array according to Claim 7 in which said organic resin is an epoxy resin.

9. A fuse array according to any one of the preceding Claims in which the compartments containing the conductive links of fusible wire or tape are filled with an electrically insulating material.

10. A fuse array according to any one of the preceding Claims in which a cover is provided for that face of the housing opposite the said base.

11. An electrical fuse array substantially as described herein with reference to Figure 1 and Figure 2 of the accompanying drawing.