GB2027561A

GB2027561A - Heat-recoverable articles

Info

Publication number: GB2027561A
Application number: GB7917881A
Authority: GB
Original assignee: Raychem Pontoise SA
Current assignee: Raychem SA
Priority date: 1978-05-23
Filing date: 1979-05-23
Publication date: 1980-02-20
Also published as: GB2027561B

Abstract

An article which may be used, for example, for connecting an earth conductor 13 to the outer conductor 16 of a coaxial cable 15 comprises a heat- shrinkable sleeve 9, Figure 4 and a quantity of solder 10 which is held by and/or on the sleeve, and is positioned eccentrically within the sleeve. The sleeve may comprise or have guide means capable of locating a portion of the earth conductor 13 in proximity to the quantity of solder. The earth conductor 64, Figure 17, may project from at least one end of the sleeve 61 and at least a portion 65 of the length of the conductor within the sleeve may be uninsulated,there being a quantity of solder 68, which is positioned eccentrically in the sleeve, on at least part of the uninsulated portion 65. <IMAGE>

Description

SPECIFICATION Heat-recoverable articles The present invention relates to a heat-recoverable article suitable, for example, for making an electrical connection between two electrical conductors and to a connection method using such an article.

Many articles and methods have been proposed for covering one or more substrates and/or for joining a plurality of substrates, for example for making an electrical connection between two electrically conductive substrates. Thus, for example, U.S. Patent Specification No. 3,243,211 discloses articles comprising a heat-shrinkable sleeve and a quantity of fusible material positioned within the sleeve. The fusible material may be, for example, a polymeric material or an inorganic fusible material, for example solder. An electrical connection between two conductors can be made, for example, by inserting the conductors in a sleeve which contains solder and heating the assembly to cause the sleeve to shrink and the solder to fuse.

A number of other specifications also describe articles which comprise a heat-shrinkable sleeve having a quantity of solder therein. Thus, for example, U.S. Specification No. 3,324,230 described an electrical connector which comprises a terminal pin (or similar electrical conductor) provided with a quantity of solder and having a heat-recoverable sleeve firmly installed thereon by shrinking one end of the sleeve into close contact with the pin.

Moreover, U.S. Specification No. 3,313,772 discloses a heat-shrinkable sleeve having a ring of solder therein and a ground lead (earth conductor) a portion of which is positioned between the solder ring and the sleeve.

While the articles referred to above have proved extremely useful in a wide variety of applications, they are not applicable in certain circumstances.

Thus, for example, the connector described in U.S.

Specification No. 3,324,230 is designed to facilitate the connection of a further conductor to the terminal pin, and is not ideally suited to, for example, facilitating the connection of an earth conductor to the outer conductor (normally braid) of a coaxial cable. Furthermore, although the article referred to above and disclosed in U.S. Specification No.

3,312,772 is designed for the latter use, there are circumstances in which its use can give rise to problems.

The present invention is concerned with the provision of an article comprising a heat-shrinkable sleeve containing solder, which is of use in making a connection between a first conductor, for example an earth conductor, and a second conductor, for example the outer conductor of a coaxial cable, and with the provision of a connection method using such an article.

The present invention provides an article which comprises a heat-shrinkable sleeve open at at least one end, and a quantity of solder positioned eccentrically within the sleeve and held by and/or on the sleeve, the solder being such that it does not extend round the entire inner circumference of any crosssection of the sleeve.

The quantity of solder may, if desired or required, have an appropriate amount of flux associated therewith. In one embodiment of the invention, the solder is preferably not associated, in the article before installation on the conductors to be joined, with any electrically conductive member which is infusible at the temperature to which the article is heated to cause the heat-shrinkable sleeve to shrink and the solder (and flux if present) to fuse. The quantity of solder is advantageously actually in contact with the inner surface of the sleeve.

In a cross-section through the article of the invention in the region of the quantity of solder, the area of the solder is advantageously small relative to the total area enclosed by the sleeve and the same is preferably also true in a longitudinal section through the article in the region of the quantity of solder.

Advantageously, in a cross-section through the article in the region of the solder the solder does not extend across the centre of the area enclosed by the sleeve and in such a cross-section the solder preferably does not protrude significantly into the area enclosed by the sleeve. Advantageously substantially all the solder is relatively close to the inner surface of the sleeve, and the quantity of solder is preferably positioned so as to permit the insertion into the article of a elongate article (for example the outer conductor of a coaxial cable) having dimensions only slightly smaller than those of the interior of the sleeve. Advantageously the circumferential extent of the solder in the sleeve is small relative to the inner circumference of the sleeve.The quantity of solder is advantageously localised at one or more portions of the inner circumference of the sleeve, that is in one or more segments of the sleeve. Preferably the solder is localised at one or more portions of the inner surface of the sleeve. Advantageously at least part of the solder is positioned in a projection of the outer circumference of the sleeve, which projection preferably substantially disappears on free recovery of the sleeve and fusing of the solder. The solder may if desired be partially enclosed by the material of the sleeve with part of the solder protruding, preferably to only a small extent, from the inner surface of the sleeve.

The quantity of solder may have any desired shape. In one advantageous embodiment of the invention, the quantity of solder is shaped and positioned such that when in use an elongate substrate (for example an earth conductor) is received in the sleeve and a portion of the elongate substrate is positioned in proximity to the quantity of solder, at least part of the solder is positioned between the said portion of the elongate substrate and the portion of the sleeve radially outwards of the said portion of the elongate substrate. In order to achieve this, at least part of the quantity of solder may, for example, be generally 'C' - or 'U'-shaped in cross-section, at least part of the exterior surface of the 'C' or 'U' advantageously being in contact with the inner surface of the sleeve.

The quantity of solder may comprise two parts spaced apart to permit the insertion of an elongate substrate, for example an earth conductor, between them. The two parts advantageously lie in a common cross-section of the sleeve and may be close to each other in the sleeve, but not quite touching, such that, for example, an elongate substrate of relatively small diameter may be positioned between them for connection to an elongate article of larger diameter which is also positioned within the sleeve.The configurations of the two parts may be such that the solder can retain the elongate substrate (for example an earth conductor) in a substantially fixed position in the sleeve and if each of the two parts is partially enclosed by the sleeve material (in which case part of the solder may be said to have sleeve material "wrapped" round it) with a part thereof protruding from the inner surface of the sleeve, the conductor may if desired be held in position by the projecting parts of the solder. The two parts may, for example, be opposed portions of a quantity of solder at least part of which is generally 'C' or 'U'-shaped in cross-section. Alternatively, for example, the two parts may be provided by two separate quantities of solder.Instead of being close to each other, two separate quantities of solder may be positioned substantially diametrically opposite each other in the sleeve, or may be otherwise spaced apart from each other. The or each quantity of solder may, if desired, be in the form of a ball.

The solder may be held by or on the sleeve in any desired manner. Advantageously, at least part of the solder is held in a projection of the outer circumference of the sleeve, which projection preferably substantially disappears on shrinking of the sleeve and fusing of the solder. Thus, for example, the sleeve may be provided with a receptacle for the solder by heating and deforming outwardly a portion of the sleeve and maintaining the deforming force while that portion of the sleeve cools. A receptacle formed in such a manner will, on heating, tend to recover its original shape and will thus tend to force solder contained therein towards the interior of the sleeve.Alternatively, for example, the quantity of solder may be positioned adjacent to the interior wall of a heat-shrinkable sleeve, the sleeve then being partially shrunk, under such conditions that the solder does not fuse, so that the interior wall partly surrounds the solder and the solder is firmly retained in the sleeve, complete recovery of the sleeve being prevented, where necessary, by mandrels.

In a further embodiment, the sleeve may comprise, for at least part of its length, two longitudinally extending compartments which are side-by-side to each other, one of the compartments (the small compartment) having a small cross-sectional area relative to the other (the large compartment). The quantity of solder, which in this embodiment is advantageously in the form of a ball, is retained in the small compartment, preferably being gripped by the inner walls of the small compartment. The compartments are, at least in the region of the solder and preferably throughout the length of the small compartment, in communication with each other.In use an elongate substrate, for example an earth conductor can be inserted in the small compartment whereby it is guided towards the solder, and on contact with the solder the end portion thereof may be deflected to a position in the large compartment in register with the solder, the solder thus acting both as a stop and as a means for guiding the substrate. If an elongate article is positioned in the large compartment and heat applied to cause the sleeve to shrink and the solder to fuse, at least part of the solder can flow into the large compartment to make a connection between the substrate and the article. An article wherein the sleeve comprises two longitudinally extending compartments may be made by any suitable method, for example by the use of a mandrel or by moulding.

It is, of course, also possible to use a sleeve which comprises two or more layers in which, for example, inner and outer layers cooperate to hold the solder, the arrangement being such that, on shrinking of the sleeve and fusing of the solder, the solder can, if it is not already in the desired location, be forced by the sleeve into that location. Where layers of a multilayer sleeve cooperate to hold the solder, the solder may, if desired, also be held in a projection in the outer circumference of the sleeve, which projection advantageously substantially disappears on shrinking of the sleeve and fusing of the solder.

In one example of a sleeve comprising inner and outer layers which cooperate to hold the solder, or assist in holding the solder, the inner layer may extend for only part of the length of the outer layer, the solder, for example, a solder ball or solder wire, being positioned adjacent to an end, within the sleeve, of the inner layer such that part of the solder is sandwiched between the first inner and outer layers; during installation of such an article the inner and outer layers may cooperate to "squeeze" the solder into a desired location. In a second example of such a sleeve, the inner layer could extend for substantially the entire length of the outer layer, the solder being held between the layers in register with an aperture in the inner layer through which, in use, molten solder can be forced.A further example of an inner layer of the sleeve that could cooperate with an outer layer to hold the solder is an inner layer of open cross-section. Thus, for example, a resilient inner layer of substantially 'C'-shaped cross-section could be used, a quantity of solder being held between the two arms of the 'C'.

Of course the inner layer referred to above can be replaced by any other inner part of the sleeve that can hold the solder. Alternatively, for example, the solder could be stuck to the sleeve (and thus held on the sleeve) by, for example, sticky flux.

The sleeve in the article of the invention may if desired comprise or have guide means capable of receiving and determining the radial location in the sleeve of an elongate substrate, the arrangement being such that when in use the elongate substrate is received in the guide means, a portion of the elongate substrate can be positioned in proximity to at least part of the quantity of solder. In this embodiment, therefore, the article of the invention comprises eccentrically positioned solder and guide means for locating a portion, preferably an end portion, of an elongate substrate (which may be, for example, a conductor for example an earth conduc tor) in proximity to the solder. Preferably at least a substantial part of the solder is positioned outside the guide means.In a cross-section through a preferred article according to the invention taken in the region of the guide means, a wall of the guide means may be said to divide the sleeve into two distinct compartments, although there may of course be an aperture in the wall such that the two compartments are in communication with each other for part or the whole of their length.

The guide means is preferably a channel open at both ends, although in some embodiments it may be open at only one end, and advantageously, at least part of the guide means is defined by a wall of the sleeve. Thus, for example, the guide means may be at least partly defined by a portion of an inner surface of the sleeve and a portion of a surface of an insert positioned within the sleeve.

In a preferred embodiment of the invention, the sleeve comprises a second outer layer and a second inner layer which extends for part only of the length of the outer layer and the guide means is at least partly defined by a portion of the inner surface of the said outer layer and a portion of the outer surface of the said inner layer. In this case, the sleeve can be said to comprise the guide means.

The guide means advantageously has a constriction therein or engaging an elongate substrate received in the guide means such that, although the substrate can be pushed past the constriction, accidental displacement of the substrate relative to the article may be substantially prevented. Where the guide means is at least party defined by a wall of the sleeve, the constriction is advantageously formed by an indentation in the wall of the sleeve; if a multilayer sleeve is used, the indentation may if desired be in the wall of a layer forming part of the sleeve.

The article preferably also comprises a stop for limiting the axial penetration into the sleeve of a substrate which in use is received in the sleeve.

When the sleeve comprises or has guide means, the article advantageously also comprises a stop for limiting the axial penetration into the sleeve of an elongate substrate which in use is received in the guide means. The stop may, for example, be provided by a portion of the inner wall of the sleeve and/or by the quantity of solder. An appropriate shape may be imparted to the sleeve by partial preshrinkage of at least a portion of the sleeve over an appropriately shaped mandrel. The stop is preferably positioned such that, in a longitudinal section through the sleeve, it is spaced from the end of the guide means, the solder being positioned between, although not necessarily in axial alignment with, the stop and the said end of the guide means.

In a preferred embodiment, therefore, the invention provides an article comprising a heat-shrinkable sleeve having at least one open end. A quantity of solder is positioned eccentrically in the sleeve remote from the open end. A guide means, to guide an elongate substrate into a position where a portion of it is in proximity to the solder, is advantageously provided at least in the region of the sleeve between the open end and the solder and preferably, although the guide means and the solder may overlap, at least a portion of the solder is positioned further from the open end than is the guide means. It is not essential for the guide means to extend to the open end or to the solder. A stop, which determines the axial penetration of the elongate substrate into the sleeve, is preferably provided, the stop advantageously being positioned further from the open end than is the solder.The solder is so positioned that, on fusing of the solder, the elongate substrate can be electrically connected by the solder to an elongate article received in the sleeve but not in the guide means.

In another aspect the invention provides a heatrecoverable article comprising a heat-shrinkable sleeve having two open ends, the sleeve having retained therein an elongate electrical conductor, which projects from at least one end of the sleeve, at least a portion of the length of the conductor within the sleeve being uninsulated, the conductor being an earth conductor and being so positioned in the sleeve that the article can in use be positioned around an elongate substrate having external dimensions only slightly smaller than the internal dimensions of the sleeve with the substrate extending out of both ends of the sleeve, and a quantity of solder on at least part of the said uninsulated portion, the solder being positioned eccentrically within the sleeve and being such that it does not extend round the entire inner circumference of any cross-section of the sleeve.

The present invention further provides a heatrecoverable article comprising a heat-shrinkable sleeve having two open ends and having a substantially constant cross-section throughout its length, the sleeve having retained therein adjacent to the inner surface thereof an elongate electrical conductor which projects from at least one end of the sleeve, at least a portion of the length of the conductor within the sleeve being uninsulated, and a quantity of solder on at least part of the said uninsulated portion, the solder being positioned eccentrically within the sleeve and being such that it does not extend round the entire inner circumference of any cross-section of the sleeve.

It is not essential that the portion of the conductor outside the sleeve be insulated. Advantageously, however, the conductor is insulated except for a length within the sleeve that is to take part in making an electrical connection.

The present invention also provides a heatrecoverable article comprising a heat-shrinkable sleeve having retained therein an elongate insulated electrical conductor, which projects from at least one end of the sleeve, at least a portion of the length of the conductor within the sleeve being uninsulated, and a quantity of solder on at least part of the said uninsulated portion, the solder being positioned eccentrically within the sleeve and being such that it does not extend round the entire inner circumference of any cross-section of the sleeve.

It is to be understood that the portion of conductor having the quantity of solder positioned thereon is not merely a tinned portion of the conductor; that is, the term "quantity of solder", when used in connec tion with those articles which have a preinstalled elongate conductor, is used herein to mean that in at least one cross-section through the portion of the conductor which carries the solder the amount of solder is in excess of that normally present on a pretinned conductor. Thus the quantity of solder should be sufficient to flow and wet a substrate to which the conductor is to be connected and to make an electrical connection between the conductor and the substrate. Thus there should be a connectioneffective solder quantity.Advantageously, in at least one cross-section through the portion of the conductor which carries the solder the thickness of the solder layer on the conductor is at least as great as the radius of the conductor.

The solder in those articles which contain a preinstalled elongate conductor may be, if desired or required, associated with an appropriate flux, and the quantity of solder is advantageously localised in the sleeve in the region of the conductor, and is preferably such as to permit the insertion in the article of an elongate substrate having exterior dimensions only slightly smaller than the inner dimensions of the sleeve. Thus the solder may, unless this is clearly inappropriate in the circumstances, be positioned in any manner/position mentioned earlier in this specification.The quantity of solder is preferably held merely by its engagement with the conductor, without the need for cooperation between the conductor and any other member, for example the sleeve, although retention, or enhancement of retention, by such cooperation is not excluded and the solder may in any case contact the sleeve, if desired.

The quantity of solder may have any suitable form and may be maintained on the conductor in any suitable manner. Thus, for example, the solder may be in the form of a ball or other shape which completely surrounds a cross-section through the said portion of the conductor. Provided that it is firmly held thereon, however, the solder need not completely surround a cross-section through the said portion of the conductor. If desired, the quantity of solder may be provided merely by wrapping a strip of solder in an appropriate manner about the conductor and, whatever the shape of the quantity of solderthe latter may, if appropriate, be crimped onto the conductor.If desired or required, the quantity of solder may include one or more outwardly extend ing portions, for example a pair of lugs, for enhanc ing the anchorage of the solder, and thus of the conductor, in the sleeve; during manufacture of the article the sleeve may be partially recovered into engagement with one or more such outwardly extending portions.

The conductor also is advantageously so posi tioned in the sleeve as to permit the insertion in the sleeve of an elongate substrate having exterior dimensions only slightly smaller than the inner dimensions of the sleeve. Preferably the portion of the conductor within the sleeve extends in a direc tion which is substantially parallel to the axis of the sleeve, and advantageously the insulated portion(s) of the conductor within the sleeve abut(s) the inner surface of the sleeve. The article may of course comprise two or more elongate conductors, if desired.

The conductor may be retained in the sleeve in any suitable manner. It should be understood that provided the sleeve and conductor do not become separated from one another during normal handling, it is not essential that the various components be rigidly fixed relative to each other; some slight relative movement may be permissible.

Advantageously the conductor is held by cooperation between the inner surface of the sleeve and the outer surface of at least one insert positioned within the sleeve. The insert, which is preferably in the form of a ring or sleeve, may if desired be infusible at the temperature to which in use the article is heated to cause the sleeve to shrink and the solder to fuse, in which case it is advantageously heat-shrinkable, but it is preferably fusible at that temperature such that on installation of the article the fused insert material may assist in providing environmental sealing for the connection made.Advantageously the conductor is held by cooperation between the sleeve and at least two inserts, at least one insert being positioned between the portion of the conductor having the quantity of solder thereon and each end of the sleeve; in this case, the quantity of solder is not carried by the extreme end portion of the conductor.

If only one insert is used, the solder advantageously includes one or more outwardly extending portions for enhancing the anchorage of the solder, and thus of the conductor, in the sleeve.

A further method by which the conductor may be retained in the sleeve comprises partial recovery of the sleeve about the conductor. This method may, if desired, be combined with the method described above wherein the conductor is held by one or more inserts and/or with any other method.

As indicated above, the conductor is advantageously insulated except for a length thereof within the sleeve that is to take part in making an electrical connection. Advantageously the portion of the conductor which is to take part in making the electrical connection is not the extreme end portion, and a conductor which is insulated except in a region adjacent to, but not at, the end thereof is advantageously provided by incomplete removal of a short length of insulation resulting from cutting radially through the insulation at a point in the region of the end of the conductor. Thus, for example, the short length of insulation may be moved longitudinally over the conductor until a part only of the insulation extends beyond the end of the conductor; if desired the longitudinally extending part of the short length of insulation may be cut off so that the conductor and the separate length of insulation are conterminous. When the conductor is stranded, a short length of insulation remaining on the extreme end portion of the conductor may assist in maintaining the strands in the stripped portion close together and relatively straight. Where the extreme end portion of the conductor is insulated and the conductor is retained in the sleeve by a pair of inserts positioned on either side of the quantity of solder, each insert advantageously contacts an insulated portion of the conductor.During manufacture, an insulated end portion of the conductor and an end of the sleeve may if desired contact a planar surface, making it possible to position the uninsulated portion of the conductor correctly without the need to support the conductor in the desired place; this is particularly advantageous when the sleeve is positioned vertically during manufacture.

In a preferred embodiment of the invention there is provided an article comprising a heat-shrinkable sleeve having first and second open ends and having retained therein an elongate electrical conductor an insulated portion of which projects from a first open end of the sleeve and an insulated end of which is within the sleeve, a portion of the conductor between the insulated end thereof and the first end of the sleeve being uninsulated and having a quantity of solder thereon, the conductor advantageously being retained in the sleeve by cooperation between the sleeve and first and second fusible rings the outer surface of each of which contacts an insulated portion of the conductor, the first ring being positioned between the uninsulated portion of the conductor and the first end of the sleeve and the second ring being positioned being the uninsulated portion of the conductor and the second end of the sleeve.

The heat-shrinkable sleeve used in accordance with the invention is a sleeve at least part of which will shrink on the application of heat and may comprise any material, advantageously an electrically insulating material, which may be converted to or maintained in a heat-shrinkable form. Examples of suitable materials are given in, for example, U.S.

Patent Specifications Nos. 3,086,242 and 3,297,819 and the other U.S. specifications referred to in this specification. Crosslinked polymeric materials, for example crosslinked polyvinylidene fluoride, are particularly suitable. Where a sleeve comprising two or more layers is used, the inner layer(s) need not comprise the same material as the outer layer. The sleeve is advantageously sufficiently transparent to enable the soldered connection made therein to be inspected.

The sleeve may be extruded as such, or may be formed from a sheet of material (which may if desired be heat-shrinkable) opposite edges of the sheet being joined in any suitable manner, for example by the use of a peroxide, by use of a contact adhesive (for example as disclosed in U.S. Patent No. 3,770,556), or by the use of an insert comprising a thermoplastic material and a heat-activatable crosslinking agent (see for example U.S. Patent Specifications Nos. 3,891,490 and 3,927,233 and British Patent Specification No. 1,512,727) to form the sleeve. If desired, the opposite edges of the sheet may be provided with means for making a connection between them (see for example U.S. Specifications Nos. 3,455,336,3,379,218, 3,530,898 and 3,574,313).Where the sleeve is formed from a sheet of material, the sheet may if desired be shaped to hold the quantity of solder before formation of the sleeve. Heat-shrinkabiiity may, if necessary, be im parted to a sleeve by any suitable method.

Where the sleeve comprises a plurality of layers an adhesive material may, if desired, be positioned (for example in the form of a continuous or discontinuous layer) between the layers. The presence of an adhesive is not, however, essential. If the sleeve comprises inner and outer layers, the inner layer is preferably substantially infusible at the temperature to which in use the article is heated to cause the sleeve to shrink and the solder to fuse and advantageously both the inner and outer layers are heat-shrinkable.If desired, however, the inner layer may be fusible at the temperature to which in use the article is heated to cause shrinking of the sleeve and fusing of the solder, and in one embodiment, a fusible inner layer may be formed integrally with a quantity of fusible material which is positioned, when the sleeve comprises or has guide means, between the guide means and an end of the sleeve, and, where there are no guide means, between the solder and the open end of the sleeve, the fusible material extending round the entire inner circumference of a cross-section of the sleeve and being in abutting relationship to the inner surface of the outer layer. Except in the region of the guide means, if present, the outer surface of the inner layer preferably contacts the inner surface of the outer layer and/or a further layer, which may be continuous or discontinuous, on the said inner surface.If desired, the second outer layer may be integral with the first outer layer, if present, and/or the second inner layer may be integral with the first inner layer if present; thus a single outer layer and single inner layer may, if desired, act both to hold, or assist in holding, the solder and to provide the guide means.

The heat-shrinkable sleeve may have any desired shape. One method by which a desired shape may be imparted comprises partial recovery of the sleeve round one or more appropriately-shaped mandrels.

In one preferred embodiment of the invention, at least a portion of the sleeve is resiliently deformable in cross-section and has a inner surface of a different shape from the outer surface of an elongate article on which the article is to be installed such that on deformation the sleeve will readily receive the elongate article and, on release of the deforming force, will grip the said article. Where the elongate article is a cable of substantially circular crosssection, the interior of the said portion of the sleeve is advantageously of non-circular cross-section and preferably has two long sides and two short sides, which sides are not necessarily straight. Advantageously the said portion of the sleeve is substantially rectangular in cross-section; in this embodiment, the solder may, if desired, be associated with one or both of the shorter sides of the rectangle.

During installation, slight pressure may be applied to the sides of such a sleeve of non-circular or other appropriate cross-section to impart an appropriate cross-section to the sleeve, the pressure being released after insertion of for example a cable in the sleeve so that sides of the sleeve grip the cable in position.

The sleeve may be open at one or both ends and may if desired be provided with a quantity of fusible material (for example fusible polymeric material) or other sealing material between the solder and the or each open end. Where the sleeve contains a fusible insert, this may provide the quantity of fusible material. The fusible material may act as a "dam" for the solder, preventing it from flowing out of the open end(s) of the sleeve during installation of the article and/or may enhance the environmental seal at the end(s) of the sleeve. Thus, the sleeve may force fused fusible material into close contact with a conductor received in the open end of the sleeve to provide a reliable seal.Alternatively, if an appropriate quantity of fusible material is provided, the sleeve and the fused fusible material could cooperate to produce a seal even at an open end that does not in use receive a substrate. Where the sleeve has a quantity of fusible material or one or more other inserts therein, the fusible material or other insert may be fixed in the sleeve in any appropriate manner, for example by partial recovery of the sleeve over the insert(s) to make the latter a tight fit.

The invention also provides a method of electrically connecting first and second electrical conductors, which comprises positioning the conductors in an article according to the invention and heating to cause the heat-shrinkable sleeve to shrink and the solder to fuse and make a connection between the conductors. Advantageously, a portion of each conductor is positioned in register with the solder.

Where the article comprises or has guide means, the invention also provides a method of electrically connecting first and second electrical conductors which comprises in either order or substantially simultaneously positioning the first conductor such that it is received in the guide means of such an article with a portion of the first conductor in proximity to the solder and positioning the second conductor in the sleeve, and then heating to cause shrinkage of the sleeve and flowing of the solder whereby an electrical connection is made between the conductors. Advantageously the said portion of the first conductor is an end portion.

When the quantity of solder comprises two parts spaced apart from each other, the first conductor is advantageously positioned between, and may if desired contact and be retained in position by, the two parts. The two parts may if desired act as positioning means for the first conductor. The first conductor may be, for example, an earth conductor and the second conductor, may be, for example, the braid of a coaxial cable.

The invention also provides a method of making an electrical connection which comprises positioning an article according to the invention which comprises a preinstalled elongate conductor having a quantity of solder thereon over a substrate and heating to cause shrinkage of the sleeve and fusing of the solder to make an electrical connection between the electrical conductor and the substrate.

Advantageously, the substrate is the outer conductor of a coaxial cable.

Articles constructed according to the invention may readily be manufactured without the use of complicated tooling. Furthermore, as the solder is positioned eccentrically within the sleeve and is held by and/or on the sleeve, substrates to be connected may be inserted into the sleeve such that they are in proximity to the solder and, on heating, the sleeve can force the molten solder directly radially inwardly into contact with at least one, and preferably both, of the substrates. Where the solder comprises two parts adjacent to each other, the solder may also act as additional positioning means and, optionally, retaining means for one of the substrates.

Articles constructed in accordance with the invention, which comprise eccentrically positioned solder, may be used to provide a localised soldered joint.

Thus, solder may be provided at the location(s) where it is desired to form a connection without the use of excess solder which may after fusing be present in undesired locations; for example, where an earth conductor is connected to the outer conductor of a coaxial cable, the use of the article of the invention may result in there being substantially equal amounts of solder on the earth conductor and on the outer conductor in the final assembly.

Furthermore, because it is necessary to fuse only the amount of solder which is required to form the joint, a smaller amount of heat is required, thus lessening the risk of overheating, for example, the sleeve, which in turn may make it possible, if desired, to use solder of a higher melting point than would be possible if for example a complete ring of solder were used.

When the article of the invention comprises not only localised solder, but also guide means for positioning an elongate substrate, for example an earth conductor, in the correct position relative to the solder, it is particularly easy to ensure, especially when the article also comprises a stop for limiting the axial movemnet of the elongate substrate, that a substrate will be located in the most advantageous position for efficient soldering. Furthermore, after shrinking of the sleeve, the guide means (particularly where the latter is formed between inner and outer heat-shrinkable layers of the sleeve) may act to grip the elongate substrate, for example the earth conductor, firmly in position and provide strain relief.

Where the sleeve comprises more than one layer of material (in order, for example, to define the guide means and/or to hold the solder), the inner layer may act to give additional protection to, for example, cable insulation having a low temperature rating which might otherwise be adversely affected by the heat applied to cause shrinkage of the sleeve.

As indicated earlier, at least part of the sleeve itself may be shaped to grip an elongate article for example a cable, to which a connection is to be made. At least part of such a sleeve may be such that it can be deformed during installation and, on release of the deforming forces, will grip the cable or other article. The fact that the sleeve does grip the elongate article may ensure that the sleeve is maintained in à preferred orientation in relation to the elongate article (and is preferably also so maintained during heat-recovery of the sleeve) and/ or may provide means for ensuring that, for example, a further article or member is in the correct position relative to the elongate article and/or to an insert within the sleeve. Thus, for example, in the case of the article of the invention wherein at least part of the sleeve has a substantially rectangular cross-section, the fact that the sleeve may, before (and preferably also during) recovery, grip an elongate article positioned in it makes it possible, if this is desired, to ensure that the solder is in a preferred orientation relative to the elongate article. Moreover, portions of the sleeve that, before recovery, are spaced from the elongate article may, in cooperation with the outer surface of the elongate article, define one or more compartments for locating a further substrate in a desired position, for example in relation to the elongate article and/or in relation to the solder.The fact that the sleeve and elongate article contact each other where the sleeve grips the cable may also, if the solder is appropriately positioned, assist in mantaining molten solder in a desired location during recovery of the article.

The advantages indicated above of articles comprising eccentrically positioned solder are of course also among the advantages of articles according to the invention which comprise a preinstalled elongate conductor having a quantity of solder thereon.

Moreover, as the latter article comprises a preinstalled conductor and quantity of solder, the connection of an earth conductor to, for example, the outer conductor of a coaxial cable may be effected merely by inserting the outer conductor in the article and heating; the article may thus readily be installed by an automatic process. Furthermore, the quantity of solder appropriate to a particular use may be selected during manufacture of the sleeve, and the fact that the solder is on the conductor and positioned eccentrically in the sleeve makes it possible to obtain a very good localized solder joint without the use of excess solder which may after fusing be present in undesired locations.

The situation described above in connection with articles comprising solder positioned eccentrically within a heat-shrinkable sleeve is in contract to the situation in the case of, for example a device as disclosed in U.S. Specification No. 3,312,772 which contains a complete ring of solder. In the case of such a device it has now been found that a relatively large ring of solder and hence a relatively thick sleeve is in practice required if sufficient solder is to be present at the desired location (i.e. at the point where the connection is to be made between the earth conductor and the outer conductor), so that a considerable quantity of heat must be applied to ensure complete shrinking of the sleeve and fusing of the solder, with the attendant possibility of overheating. It has also now been found that the ring of solder in U.S.Specification No. 3,312,772 provides much more solder than is needed to connect the earth conductor with the outer conductor. This is disadvantageous, not only because it wastes solder, but also because solder may reach locations in the completed connection where it should not be.

Various embodiments of the invention will now be described in greater detail, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows an article according to the inven tion; Figure 2 is a cross-section through an article of the invention which includes two balls of solder; Figure 3 is a cross-section through an article according to the invention which includes one ball of solder; Figure 4 illustrates the use of an article according to the invention to connect an earth conductor to the braid of a coaxial cable; Figure 5 is a view of a further article according to the invention; Figure 6 is a cross-section through the article of Figure 5; Figure 7 illustrates the use of the article of Figures 5 and 6 to connect an earth conductor to the braid of a coaxial cable;; Figures 8 to 10 are cross-sections through further articles according to the invention.

Figure 11 is a perspective view of one embodiment of the invention; Figure 12 is an enlarged longitudinal section through the article of Figure 11; Figure 13 is a cross-section taken on the line A-A in Figure 12; Figure 14 is a perspective view of another embodiment of the invention; Figure 15 shows an article according to the invention having two longitudinally extending compartments, Figure 16 is a view of one end portion of the article shown in Figure 15; Figure 17 is a perspective view of an article according to the invention which includes a preinstalled conductor, and Figures 18to 20 are perspective view showing electrical conductors for use in an article which includes a preinstalled conductor, the conductors having quanties of solder of different shapes thereon.

Referring now to the drawings, Figure 1 shows an article, indicated generally by the reference numeral 1, which comprises a heat-shrinkable sleeve 2 and a pair of balls 3,3 of solder (and if desired flux) retained in the sleeve 2 by partially recovered portions of the latter. Each of the solder balls 3 is partially enclosed by the sleeve material and has a portion projecting from the inner portion of the sleeve. As can most clearly be seen from Figure 2, the solder balls, indicated in Figure 2 as 3a, 3a, are so positioned that a conductor, for example an earth conductor, can be positioned between them. The solder balls may act as positioning and retaining means for a conductor. The solder balls are remote from both ends of the sleeve.

The article shown in Figure 1 has an elongate raised portion 4, formed by partial recovery of the sleeve around a mandrel, extending from one open end to the solder balls 3,3 to guide a conductor towards the solder balls. Although articles containing two solder balls are advantageous for some uses, for other uses one solder ball is sufficient, and Figure 3 is a crosss-section through an article containing only one solder ball 5, the solder ball 5 being retained in position in a heat-shrinkable sleeve 6 by necked-in portions 7 of the sleeve 6. The receptacle for the solder in Figure 3 may if desired be made sufficiently large to accommodate one of the conductors to be connected.

Figure 4 shows the use of an article constructed in accordance with the invention to connect an earth conductor to the braid of a coaxial cable. The article of Figure 4, which is indicated generally by the reference numeral 8, is similar to the article of Figure 1 and comprises a heat-shrinkable sleeve 9 of electrically insulating material and two balls of solder, only one of which, indicated by the reference numeral 10, can be seen in Figure 4. The article 8 also contains two rings, 11 and 12 respectively, of fusible polymeric material, each of the rings 11 and 12 being positioned between the balls of solder and an open end of the sleeve 9.

As is shown in Figure 4, a stripped end portion 14 of an insulated earth conductor 13 may be positioned between the two balls of solder so that it is adjacent both to the solder (and may if desired be positioned and retained by the solder) and to-an exposed length of braid 16 of a coaxial cable, indicated generally by reference numeral 15, over which the article is positioned, the cable 15 also having an exposed length of dielectric 17 and an exposed length of centre conductor 18, the length of centre conductor 18 and a portion of the dielectric 17 extending out of the end of sleeve 9. The earth conductor and the coaxial cable can be inserted into the article in either order or substantially simultaneously.When the earth conductor and the coaxial cable are positioned as indicated in Figure 4, heat may be applied to cause the sleeve 9 to shrink and the solder balls and fusible rings 11 and 12 to fuse, whereby a soldered connection is made between the braid and the earth conductor and the sleeve 9 is sealed to the cable dielectric 17 and to the cable insulation 19 and the insulation of the earth conduc tor13.

Figure 5 shows a perspective view of an article according to the invention wherein the sleeve, indicated generally by the reference numeral 20, is of substantially rectangular cross-section and is resiliently deformable. Pressure may be applied to the shorter sides of such a sleeve during installation thereof to cause the sleeve to adopt a substantially circular cross-section whereby, for example, a cable of circular cross-section can readily be inserted therein. On release of the pressure, the sleeve returns substantially to its original shape so that the long sides thereof grip the cable in position.The fact that the sleeve grips the cable (or other substrate) makes it possible, if this is desired, to ensure that a quantity of solder within the sleeve (see below) is in a particular location relative to the cable or other substrate, and portions of the sleeve which, before recovery, are spaced from the substrate may, in cooperation with the surface of the substrate, define one or more compartments for locating a further substrate, for example an earth conductor, in a desired location, for example in relation to the cable and/or in relation to the solder. The fact that the cable and sleeve are in contact when the sleeve grips the cable may also assist in maintaining molten solder in a desired location during recovery of the article.

As can more clearly be seen in Figures 6 and 7 the sleeve 20 comprises an outer layer 21 and an inner layer 22. The inner layer 22 extends from one end 23 of the outer layer to approximately halfway along the length of the outer layer 21. On each of the shorter sides of the sleeve, the end portion of the inner layer and a portion of the outer layer in the region of the centre of the sleeve cooperate to hold a respective ball 24 of solder (and if desired flux), part of each solder ball 24 being positioned between and being held by the inner and outer layers of the sleeve; the outer layer 21 protrudes outwardly and the inner layer 22 protrudes inwardly in the region of the solder balls.The device of Figures 5 to 7 also comprises two rings 11 and 12 of fusible polymeric material, these rings being similarly positioned to, and performing a similar function to, the rings 11 and 12 in Figure 4.

Figure 7 shows the use of the article of Figures 5 and 6 to connect the stripped end portions 14 of two insulated earth conductors 13 to an exposed length of braid 16 of a coaxial cable 15 similar to that shown in Figure 4. Each end portion is positioned adjacent to a respective solder ball 24. The earth conductors and the coaxial cable can be inserted into the article in any order or substantially simultaneously. When the earth conductors and the coaxial cable are positioned as indicated in Figure 7, heat may be applied to cause the sleeve 20 to shrink and the solder balls 24 and fusible rings 11 and 12 to fuse, whereby an electrical connection is made between the braid and the earth conductors and the sleeve 20 is sealed to the cable dielectric 17 and to the cable insulation 19 and the insulation of the earth conductor 13.The fused solder is forced out from between the inner and outer layers of the sleeve during shrinkage of the sleeve and the inner layer 22 may also act as an additional protecting layer for, for example, a cable dielectric that might otherwise be adversely affected by the heat applied to cause recovery of the sleeve and fusing of the solder.

An article such as that shown in Figures 5 to 7 may be made by positioning tubular members of substantially circular cross-section which are to form the inner and outer layers of the sleeve around a vertical mandrel of substantially rectangular cross-section, positioning the solder balls between the two tubular members adjacent to one end of the inner member and heating the assembly at a temperature which does not cause fusing of the solder to cause the tubular members to shrink and grip the mandrel and the solder, the degree of shrinkage being such that the composite sleeve so formed is still heatshrinkable. Although this is not essential, an adhesive material could be provided between the inner and outer layers, e.g., as an interior coating on the outer tubular member or an exterior coating on the inner tubular member.

Figure8 is generally similarto Figure 6 except that each of the short sides of a cross-section through the sleeve 20 is provided with a pair of balls 25 of solder (and if desired flux). Each pair of solder balls 25 may act as positioning and retaining means for a conductor such as an earth conductor. Thus, e.g., a conductor may be received in the opening of substantially triangular croos-section defined by the two solder balls and the outer wall of the inner layer.

The use of two solder balls may be advantageous where more solder is required, e.g., where a thicker conductor is to be used. It would of course, be possible for one of the short sides of the substantially rectangular cross-section to be provided with one solder ball and the other short side with two solder balls.

Figure 9 is a cross-section through an article according to the invention in which the sleeve 25 comprises an outer layer 26 and an inner layer 27 of substantially 'C'-shaped cross-section, a ball 28 of solder (and if desired flux) being held between the arms of the 'C'.

The article shown in cross-section in Figure 10 does not include an inner layer. Instead, a ball 29 of solder is stuck to the inner wall of a heat-shrinkable sleeve 30 by means of sticky flux.

The article shown in Figures 11 to 13 comprises a heat-shrinkable sleeve 31 having positioned eccentrically within it a strip 32 of solder (and if desired flux) which is generally'C'-shaped in cross-section.

The outer surface of the 'C' is firmly engaged by a portion of the inner surface of the sleeve 31, the said portion having previously been partially shrunk into close contact with the solder strip 32; in this embodiment therefore, the solder is held solely by the sleeve 31.

The article of Figures 11 to 13 also comprises a guide channel 33 capable of receiving and locating, for example, an earth conductor whereby the end of the earth conductor may be positioned in proximity to, and in the direction of recovery of, the solder strip 32. The guide channel is defined by the inner surface 34 of the sleeve 31 and the outer surface 35 of an inner sleeve 36 positioned within the sleeve 31, the sleeve 31 can be said to form the outer layer and the sleeve 36 the inner layer of a multi-layer sleeve.

Except in the region of the guide channel 33, the inner sleeve 36 is in contact with the outer sleeve 31.

The guide channel 33 has a constriction therein formed by an indentation 37 in the sleeve 31 for gripping, for example, the insulation of an earth conductor received in the guide channel 33.

As can be seen from the drawings, when an elongate substrate, for example an earth conductor (not shown in the drawings) is received in the guide channel 33 the end portion of the substrate may be positioned between the "arms" of the 'C'-shaped solder strip; the sleeve 31 is shaped such that a portion 38 of its inner surface provides a stop to limit the axial penetration of for example the earth conductor into the sleeve. When an earth conductor is positioned in this way and heat is applied to cause the sleeve 31 to shrink and the solder to fuse, molten solder is forced radially inwards by the sleeve into contact with the end portion of the earth conductor and into contact with a second substrate (for example the braid of a coaxial cable) which may previously have been introduced into the sleeve.

A ring (or layer), 39 and 40 respectively, of fusible polymeric material is provided in the region of each end of the sleeve 31, the ring 40 being positioned between the guide means and the open end adjacent thereto. The polymeric material may, after installation of the sleeve, provide a seal to the substrate(s) positioned in the sleeve. One end portion 41 of the sleeve 31 (and the associated fusible layer 39) is generally rectangular in cross-section to enable that end portion to grip a substrate, for example a cable, on which the article is mounted so that the article may be reliably retained in the desired position during the heating step.

The article shown in Figure 14 differs from that shown in Figures 11 to 13 primarily in the form of the quantity of solder and the manner in which this is retained in the sleeve 31. The solder in the article shown in Figure 14 is in the form of a wire 42 of substantially circular cross-section, each of the end portions 43 and 44 of the wire extending in an axial direction and being held by cooperation between the inner surface of the sleeve 31 and the outer surface of a sleeve 45 positioned within the sleeve 31; the sleeve 31 can be said to form the outer layer and the sleeve 45 the inner layer of a multi-layer sleeve.The centre portion 46 of the solder wire 42 lies in a plane which is substantially perpendicular to the plane containing the end portions 43 and 44 of the wire and is so shaped that in a cross-section through the article which contains the centre portion the solder is generally U-shaped, with the curved portion of the U in contact with the interior of the sleeve 31. The sleeve 31 is partially preshrunk around the centre portion 46 of the wire to assist in maintaining the wire in the desired position in the sleeve. In the article of Figure 14, the sleeve 45 acts both to hold the solder and, together with the sleeve 31, to define the guide channel for, for example, the earth conductor.

In a modification (not shown) of the article shown in Figure 14, the centre portion of the solder wire may lie in the same plane as the end portions of the wire. In this embodiment, the centre portion of the wire may act as an axial stop for the first substrate.

Figure 15 shows an article according to the invention, a view of one end of which is shown in Figure 16, wherein the sleeve comprises two longitudinally extending compartments positioned side-byside to each other, the article having an earth conductor inserted therein.

The article of Figure 15 comprises a sleeve indicated generally by the reference numeral 50 comprising two compartments 51 and 52 respectively, the cross-sectional area of compartment 51 being small relative to the cross-sectional area of the compartment 52. In the article shown in Figure 15 the compartment 51 extends longitudinally from one open end 53 of the compartment 52 to a point 54 intermediate between the ends of the compartment 52, the two compartments being in communication with each other, via a longitudinally extending opening 54 (see Figure 16) throughout the length of the compartment 51. A ball 55 of solder is positioned in the compartment 51, and is gripped by the walls thereof, adjacent to the end 54 of compartment 51 remote from the open end 53 of the compartment 52.

In use of the article shown in Figure 15, an uninsulated end portion 56 of an insulated conductor indicated generally by the reference numeral 57 may be inserted into the open end of the compartment 51 and the conductor 57 may be pushed along the compartment until the end 56 thereof contacts the solder ball 55 and is deflected downwards (as shown in Figure 15) to lie below the solder ball 55 in the compartment 52. The width of opening 54 is preferably chosen such that the insulated portion of conductor 57 cannot readily pass through it. On insertion of a substrate, for example the outer conductor of a coaxial cable (not shown in Figure 15) into the large compartment 52 and heating, a reliable soldered connection may be made between the substrate and the end portion 56, the fused solder flowing through opening 54 and the small compartment 51 shrinking tightly round the conductor 57.In the above method, the small compartment 51 acts as guide means, and the solder ball 55 also acts to guide the end portion 56 of the conductor into the desired location.

Referring now to Figure 17, a heat-shrinkable sleeve 61 has open ends 62 and 63 respectively. An insulated conductor indicated generally by the reference numeral 64 having an uninsulated portion 65 within the sleeve extends from the open end 62 of the sleeve. The end of the conductor 64 is insulated by a short length of insulation 66, and insulation 67, is present on the portion of the conductor 64 between the uninsulated portion 65 and the open end 62 of the sleeve. A ball 68 of solder surrounds part of the uninsulated portion 65 of the conductor 64.

The portion of the conductor 64 within the sleeve 61 extends in a direction which is generally parallel to the axis of the sleeve with the portions of insulation 66 and 67 (and the solder ball 68) contacting the inner surface of the sleeve. The conductor 64 is retained in position in the sleeve by cooperation between the sleeve and two rings of fusible material, 69 and 70 respectively. The ring 69 is positioned between the uninsulated portion 65 of the conductor and the open end 62 of the sleeve, a portion of insulation 67 being sandwiched between the outer surface of the ring 69 and the inner surface of the sleeve 61. Similarly, a portion of insulation 66 is sandwiched between the outer surface of the ring 70, which is positioned between the uninsulated portion 65 of the conductor and the open end 63 of the sleeve, and the inner surface of the sleeve.The sleeve has been partially recovered from a diameter greater than that shown, to fix the conductor 64 and the rings 69 and 70 in position so that they do not move significantly with respect to each other or to the sleeve 61.

In the embodiment of the invention shown in Figure 17, the conductor and the solder thereon are close to the inner surface of the sleeve and thus permit the insertion in the sleeve of a substrate having exterior dimensions only slightly smaller than the internal dimensions of the sleeve. Such a substrate, for example a coaxial cable having an exposed length of outer conductor, may be inserted in the sleeve such that the said length of outer conductor is adjacent to solder ball 68 and the assembly may then be heated to cause the sleeve to shrink and the solder ball 68 and fusible rings 69 and 70 to fuse so that a soldered connection is made between the uninsulated portion 65 of the conductor 64 and the outer conductor of the coaxial cable and an enviromental seal is made, if desired.When, as shown in the drawings, the sleeve 61 is transparent the soldered connection may readily be inspected, but where such visual inspection is not necessary use of a transparent material is not essential.

Figures 18 to 20 show quantities of solder of different shapes on an uninsulated portion 65 of the conductor 64. The quantity of solder 71 shown in Figure 18 is formed by crimping a strip of solder around the portion 65, the resultant quantity of solder being, in cross-section, in the form of a compressed 'C'. Thus, in a cross-section through solder 71, the centre portion 72 and end portions 73 of the solder strip contact opposite sides of the conductor, with the end portions slightly spaced from each other, and the part of the strip between the central portion and each end portion is folded on itself to provide a pair of diametrically opposed outwardly extending portions 74 of solder each of which has, in cross-section, a lateral extent greater than the thickness of the solder strip.

Figure 19 shows a quantity of solder in the form of a ball 75 provided with a pair of diametrically opposed outwardly extending lugs 76 which may, if the sleeve is partially recovered into engagement with at least one of them, enhance the anchorage of the conductor 64 in the sleeve 61. The quantity of solder 77 shown in Figure 20 is substantiallytriangu- lar in cross-section, and has a slit 78 therein whereby it is open in cross-section so that it can be forced onto the uninsulated portion 65 of the conductor; in the case of a stranded conductor this step may be facilitated by movement of the strands relative to one another. The slit 78 communicates with a central hole 79 in the solder 77, the dimensions of the hole being such that the solder 77 is held tightly on the conductor.

The quantities of solder shown in Figures 18to20 may if desired be used in an article as shown in Figure 17 in place of the solder ball 68 used therein, or may be used in any other article constructed in accordance with the invention which includes a preinstalled electrical conductor. One or both of the outwardly extending portions 74 in Figure 18 and one or more of the apices of the triangle which is the cross-section through the quantity of solder 77 in Figure 20 may if desired act in the same manner as the lugs 76 in Figure 19, namely to enhance the anchorage of the solder, and hence the anchorage of the conductor 74, in the sleeve.One situation where such enhancement may be desirable is where the short length of insulation 66 in Figure 17 is absent (which may be the case if, for example the uninsulated portion of the conductor is tinned), in which case the article may comprise only one ring of fusible material (for example ring 69 in Figure 17, ring 70 being absent).

It will be noted that in all the Figures apart from Figure 10 at least part of the solder is positioned in a projection in the outer circumference of the sleeve.

In the case of the sleeves shown in the drawings the said projection will substantially disappear, or become less pronounced, on free recovery of the sleeve and fusing of the solder.

When the article of the invention comprises a preinstalled elongate electrical conductor having a quantity of solder thereon, the article may, if desired, comprises more than one such conductor.

Examples of elongate electrical conductors which may be used in the article of the invention which comprises a preinstalled conductor are earth conductors and electrically conductive pins, for example terminal pins. In articles which comprise a preinstalled conductor, it is to be understood that a sleeve which has a substantially constant cross-section throughout its length may have an additional portion, for example, an end portion, of a different cross-sectional shape and/or size provided that an appreciable part of the inner circumference of the additional portion is spaced to a significant extent from the conductor, that is, provided the additional portion is not recovered into close contact with the conductor.

Claims

1. An article which comprises a heat-shrinkable sleeve open at at least one end, and a quantity of solder positioned eccentrically within the sleeve and held by and/or on the sleeve, the solder being such that it does not extend round the entire inner circumference of any cross-section of the sleeve.

2. An article as claimed in claim 1, wherein in a cross-section through the article in the region of the quantity of solder, the area of the solder is small relative to the total area enclosed by the sleeve.

3. An article as claimed in claim 1 or claim 2, wherein in a cross-section through the article in the region of the quantity of solder the solder does not protrude significantly into the area enclosed by the sleeve.

4. An article as claimed in any one of claims 1 to 3, wherein the quantity of solder is positioned so as to permit insertion in the sleeve of an elongate article having dimensions only slightly smaller than those of the interior of the sleeve.

5. An article as claimed in any one of claims 1 to 4, wherein the quantity of solder is localised at one or more portions of the inner surface of the sleeve.

6. An article as claimed in any one of claims 1 to 5, wherein the quantity of solder comprises two parts spaced apart from each other to permit the insertion of a portion of an elongate substrate between them.

7. An article as claimed in claim 6, wherein the two parts lie in a common cross-section of the sleeve.

8. An article as claimed in claim 6 or claim 7, wherein the two parts are close to, but do not touch, each other.

9. An article as claimed in any one of claims 6 to 8, wherein the two parts are opposed portions of a quantity of solder at least part of which is generally 'C'- or 'U'-shaped in cross-section.

10. An article as claimed in any one of claims 1 to 9, wherein the quantity of solder is so shaped and positioned that when in use an elongate substrate is received in the sleeve and a portion of the elongate substrate is positioned in proximity to the quantity of solder, at least part of the solder is positioned betwen the said portion of the elongate substrate and the portion of the sleeve radially outwards of the said portion of the elongate substrate.

11. An article as claimed in any one of claims 1 to 10, wherein at least part of the quantity of solder is generally 'C'- or 'U'-shaped in cross-section.

12. An article as claimed in claim 11, wherein at least part of the exterior surface of the 'C' or 'U' is in contact with the inner surface of the sleeve.

13. An article as claimed in any one of claims 1 to 12, wherein the quantity of solder is localised at one portion of the inner surface of the sleeve, is generally 'C'-shaped in cross-section, and is held solely by the sleeve.

14. An article as claimed in claim 6 or any claim dependent thereon, wherein the two parts are separate quantities of solder.

15. An article as claimed in claim 14, wherein the two quantities of solder are positioned substantially diametrically opposite to each other in the sleeve.

16. An article as claimed in any one of claims 1 to 8, claim 14 and claim 15, wherein the or each quantity of solder is in the form of a ball.

17. An article as claimed in any one of claims 1 to 16, wherein at least part of the solder is positioned in a projection of the outer circumference of the sleeve.

18. An article as claimed in claim 17, wherein the projection substantially disappears on free recovery of the sleeve and fusing of the solder.

19. An article as claimed in any one of claims 1 to 18, wherein the or each quantity of solder is held in position in the sleeve by a partially shrunk portion of the sleeve.

20. An article as claimed in any one of claims 1 to 19, wherein the or each quantity of solder is partially enclosed by the material of the sleeve.

21. An article as claimed in any one of claims 1 to 20, wherein the sleeve comprises, for at least part of its length, two longitudinally extending compartments which are side by side to each other and one of which is of small cross-sectional area relative to the other, the quantity of solder being positioned in the compartment of smaller cross-sectional area and the two compartments being in communication with each other at least in the region of the solder.

22. An article as claimed in claim 21, wherein the compartments are in communication with each other throughout the length of the smaller compartment.

23. An article as claimed in claim 21 or claim 22, wherein the quantity of solder is held by the inner walls of the smaller compartment.

24. An article as claimed in any one of claims 1 to 23, wherein the sleeve comprises a plurality of layers which cooperate to hold the solder.

25. An article as claimed in claim 24, wherein the sleeve comprises a first outer layer and a first inner layer which extends for part only of the length of the first outer layer, the solder being held by cooperation between an end portion of the first inner layer and the portion of the first outer layer adjacent to said end portion of the first inner layer.

26. An article as claimed in claim 25, wherein the quantity of solder comprises one or more portions which extend longitudinally in the sleeve and are sandwiched between the first inner layer and the first outer layer and one or more portions which are not positioned between the said layers.

layers.

27. An article as claimed in any one of claims 24 to 26, wherein the first inner layer has a substantially 'C'-shaped cross-section, the quantity of solder being held between the arms of the 'C'.

28. An article as claimed in any one of claims 1 to 27, wherein the solder is held by the sleeve.

29. An article as claimed in any one of claims 1 to 28, wherein the solder is stuck to the inner wall of the sleeve.

30. An article as claimed in claim 29, wherein the solder is stuck to the sleeve by sticky flux.

31. An article as claimed in any one of claims 1 to 30, wherein the sleeve also comprises or has guide means for receiving and determining the radial location in the sleeve of an elongate substrate, the arrangement being such that when in use the elongate substrate is received in the guide means, a portion of the elongate substrate can be positioned in proximity to at least part of the quantity of solder.

32. An article as claimed in any one of claims 1 to 31, wherein the quantity of solder is positioned remote from the open end of the sleeve and wherein a guide means, to receive an elongate substrate and to guide it into a position wherein a portion thereof is in proximity to the solder, is provided at least in the region between the open end and the solder.

33. An article as claimed in claim 31 or claim 32, wherein at least a substantial part of the solder is positioned outside the guide means.

34. An article as claimed in any one of claims 31 to 33, wherein at least a portion of the solder is positioned further from the open end of the sleeve than is the guide means.

35. An article as claimed in any one of claims 31 to 34, wherein the quantity of solder is positioned such that when in use the elongate substrate is received in the guide means and a portion of the elongate substrate is positioned in proximity to the quantity of solder at least part of the solder is positioned between the said portion of the first substrate and the portion of the sleeve radially outwards of the said portion of the first substrate.

36. An article as claimed in any one of claims 31 to 35, wherein the quantity of solder comprises two parts spaced apart from each other such that when in use the elongate substrate is received in the guide means a portion of the elongate substrate can be positioned between the two parts.

37. An article as claimed in any one of claims 31 to 36, wherein the guide means comprises a channel having two open ends.

38. An article as claimed in any one of claims 31 to 37, wherein at least part of the guide means is defined by a wall of the sleeve.

39. An article as claimed in any one of claims 31 to 38, wherein the guide means is at least partly defined by a portion of the inner surface of the sleeve and at least part of a surface of an insert positioned within the sleeve.

40. An article as claimed in any one of claims 31 to 38, wherein the sleeve comprises a second outer layer and a second inner layer which extends for part only of the length of the second outer layer and wherein the guide means is at least partly defined by a portion of the inner surface of the second outer layer and a portion of the outer surface of the second inner layer.

41. An article as claimed in claim 40, wherein, except in the region of the guide means, the outer surface of the second inner layer contacts the inner surface of the second outer layer and/or a further layer on the said inner surface.

42. An article as claimed in claim 40 or claim 41, wherein at least part of the second inner layer is fusible at the temperature to which in use the article is heated to cause shrinking of the heat-shrinkable sleeve and fusing of the solder.

43. An article as claimed in claim 42, wherein the second inner layer is formed integrally with a quantity of fusible material which is positioned between the guide means and an end of the sleeve, the fusible material extending round the entire inner circumference of a cross-section of the sleeve and being in abutting relationship to the inner surface of the second outer layer.

44. An article as claimed in any one of claims 40 to 43, wherein the sleeve comprises first inner and outer layers and wherein a single outer layer provides both the first outer layer and the second outer layer.

45. An article as claimed in any one of claims 40 to 44, wherein the sleeve comprises first inner and outer layers and wherein a single inner layer provides both the first inner layer and the second inner layer.

46. An article as claimed in any one of claims 31 to 45, wherein the guide means has a constriction therein for engaging an elongate substrate received, in use, in the guide means.

47. An article as claimed in claim 46, wherein the constriction is formed by an indentation in the wall of the sleeve.

48. An article as claimed in any one of claims 1 to 47, which also comprises a stop for limiting the axial penetration into the sleeve of a substrate which in use is received in the sleeve.

49. An article as claimed in any one of claims 31 to 48, which also comprises a stop for limiting the axial penetration into the sleeve of an elongate substrate which in use is received in the guide means.

50. An article as claimed in claim 48 or claim 49, wherein the stop comprises a portion of the interior wall of the sleeve.

51. An article as claimed in any one of claims 48 to 50, wherein the stop comprises the quantity of solder.

52. An article as claimed in claim 25 or any claim dependent thereon or claim 40 or any claim dependent thereon, wherein both the inner and outer layers are heat-shrinkable.

53. An article as claimed in claim 25 or any claim dependent thereon or claim 40 or any claim dependent thereon, wherein at least one layer comprises a different material from the other layer(s).

54. An article as claimed in any one of claims 1 to 53, wherein at least a portion of the sleeve is resiliently deformable in cross-section and is of non-circular internal cross-section.

55. An article as claimed in claim 54, wherein the said portion of the sleeve has two long sides and two short sides.

56. An article as claimed in claim 54 or claim 55, wherein the said portion of the sleeve is substantially rectangular in cross-section.

57. An article as claimed in claim 56, wherein the or each quantity of solder is adjacent to a short side of the rectangle.

58. An article as claimed in any one of claims 1 to 57, wherein the sleeve has a longitudinal seam therein.

59. An article as claimed in claim 58, wherein the sleeve has been formed from a sheet of material opposite edges of which are provided with means for connecting the said edges.

60. An article as claimed in any one of claims 1 to 59, wherein the sleeve is open at both ends.

61. An article as claimed in any one of claims 1 to 60, wherein the sleeve comprises electrically insulat ing material.

62. An article as claimed in any one of claims 1 to 61,wherein a quantity of fusible material is posi tioned between the solder and the or each open end of the sleeve.

63. An article constructed substantially as de scribed herein with reference to, and as illustrated by, Figures 1 to 3, or Figure 4 or Figures 5 to 7, or any one of Figures 8 to 10, or Figures 11 to 13 or Figure 14 or Figures 15 and 16 or any one of Figures 18 to 20 of the accompanying drawings.

64. A heat-recoverable article comprising a heat shrinkable sleeve having two open ends, the sleeve having retained therein an elongate electrical con ductor, which projects from at least one end of the sleeve, at least a portion of the length of the conductor within the sleeve being uninsulated, the conductor being an earth conductor and being so positioned in the sleeve that the article can in use be positioned around an elongate substrate having external dimensions only slightly smaller than the internal dimensions of the sleeve with the substrate extending out of both ends of the sleeve, and a quantity of solder on at least part of the said uninsulated portion, the solder being positioned eccentrically within the sleeve and being such that it does not extend round the entire inner circumfer ence of any cross-section of the sleeve.

65. A heat-recoverable article comprising a heat shrinkable sleeve having two open ends and having a substantially constant cross-section throughout its length, the sleeve having retained therein adjacent to the inner surface thereof an elongate electrical conductor which projects from at least one end of the sleeve, at least a portion of the length of the conductor within the sleeve being uninsulated, and a quantity of solder on at least part of the said uninsulated portion, the solder being positioned eccentrically within the sleeve and being such that it does not extend round the entire inner circmference of any cross-section of the sleeve.

66. A heat-recoverable article comprising a heatshrinkable sleeve having retained therein an elongate insulated electrical conductor, which projects from at least one end of the sleeve, at least a portion of the length of the conductor within the sleeve being uninsulated, and a quantity of solder on at least part of the said uninsulated portion, the solder being positioned eccentrically within the sleeve and being such that it does not extend round the entire inner circumference of any cross-section of the sleeve.

67. An article as claimed in any one of claims 64 to 66, wherein the conductor is insulated except for a length within the sleeve that is to take part in making an electrical connection.

68. An article as claimed in any one of claims 64 to 67, wherein the conductor projects from one end only of the sleeve and wherein the extreme end portion of the conductor within the sleeve is insulated.

69. An article as claimed in any one of claims 64 to 68, wherein the quantity of solder is localized in the region of the conductor.

70. An article as claimed in any one of claims 64 to 69, wherein the quantity of solder is crimped onto the conductor.

71. An article as claimed in any one of claims 64 to 70, wherein the quantity of solder comprises a plurality of outwardly extending portions.

72. An article as claimed in any one of claims 64 to 71, wherein the conductor is held by cooperation between the inner surface of the sleeve and an outer surface of at least one insert positioned within the sleeve.

73. An article as claimed in any one of claims 64 to 72, wherein the said insert is fusible at the temperature to which in use the article is heated to cause shrinking of the sleeve and fusing of the solder.

74. An article as claimed in claim 72 or claim 73, wherein the insert is in the form of a ring.

75. An article as claimed in any one of claims 72 to 74, wherein there are at least two inserts, at least one insert being positioned between the portion of the conductor having the quantity of solderthereon and each end of the sleeve.

76. An article as claimed in any one of claims 72 to 75, wherein each insert contacts an insulated length of the conductor.

77. An article comprising a heat-shrinkable sleeve having first and second open ends and having retained therein an elongate electrical conductor an insulated portion of which projects from a first open end of the sleeve and an insulated end of which is within the sleeve, a portion of the conductor between the insulated end thereof and the first end of the sleeve being uninsulated and having a quantity of solder thereon.

78. An article as claimed in claim 77, wherein the conductor is retained in the sleeve by cooperation between the sleeve and first and second fusbile rings the outer surface of each of which contacts an insulated portion of the conductor, the first ring being positioned between the uninsulated portion of the conductor and the first end of the sleeve and the second ring being positioned being the uninsulated portion of the conductor and the second end of the sleeve.

79. A method of electrically connecting first and second electrical conductors, which comprises positioning the conductors in an article as claimed in any one of claims 1 to 63 and heating to cause the heat-shrinkable sleeve to shrink and the solder to fuse and make a connection between the conductors.

80. A method of connecting first and second electrical conductors which comprises, in either order or substantially simultaneously, positioning the first conductor such that it is received in the guide means of an article as claimed in claim 31 or any claim dependent thereon with a portion of the first conductor in proximity with the solder and positioning the second conductor in the sleeve, and then heating to cause shrinkage of the sleeve and flowing of the solder whereby an electrical connection is made between the conductors.

81. A method as claimed in claim 80, wherein the said portion of the first conductor is an end portion.

82. A method as claimed in claim 80 or claim 81, wherein the quantity of solder comprises two parts spaced apart from each other and wherein the first conductor is positioned between the two parts.

83. A method as claimed in claim 82, wherein two parts of solder act as positioning means for the first conductor.

84. A method as claimed in any one of claims 79 to 83, wherein the article comprises a stop for limiting the axial penetration of the first conductor into the sleeve and wherein the first conductor is positioned in the sleeve such that a portion of the first conductor abuts the stop.

85. A method as claimed in any of claims 79 to 84, wherein the first conductor is an earth conductor and the second conductor is the outer conductor of a coaxial cable.

86. A method of making an electrical connection which comprises positioning an article as claimed in any one of claims 64 to 78 over a substrate and leating to cause shrinkage of the sleeve and fusing of the solder to make an electrical connection between the conductor and the substrate.

87. A method as claimed in claim 86, wherein the substrate is the outer conductor of a coaxial cable.

88. A method of making an electrical connection carried out substantially as described herein.

89. An electrical connection whenever made by a method as claimed in any one of claims 79 to 87.