Note: Descriptions are shown in the official language in which they were submitted.
~3~
m is invention relates to heat-recoverable articles,
more especially to heat-s~rinkable sleeves having solder
therein.
It is known to make insulated soldered connections
between a pair of electrical conductors by the use of a
device which comprises a heat-shrinkable sleeve of
insulating material which contains a ring of solder
positioned at its central region. The sleeve may also be
provided, at one or both ends, with a quantity of a fusible
material, which melts when the sleeve is heated to cause
recovery, and provides environmental sealing for the
resulting connection. The fusible material may also serve
to prevent escape of solder from:the end o~ the sleeve or,
if there is no fusible material provided, this may be
achieved by the recovery of the ends of the sleeve around
the conductors, or their insulation.
Heat-shrinkable sleeves containing solder, which are
described in U.S. Patent ~o. 3,243,211, have found many
applications including, for example, the attachment of an
earth conductor to the outer conductor of a coaxial cable.
Thus for example U.S. Specification No. 3,312,772 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,
The ~resent invention is concerned with the provision
of a heat-shrinkable sleeve containing solder, which is
of use in making a connection between a first
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conductor, for example an earth conductor, and a second
conductor, for example the outer c~nductor of a coaxial
cable.
The present invéntion accordingly provides a
heat-recoverable 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
~5 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 heat-
recoverable article comprising a heat-shrin~able 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
el~ngate 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
'
~ 4 --
~uantity of solder on at least part of the said unin-
sulated 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. Advantageousl~,
however, the conductor is insulated except for a length
within tne sleeve that is to take ~art in making an
electrical connection.
The ~resent invention also provides a heat-
recoverable 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" 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.
~3~
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 o~nductor and the substrate. Thus there should be a
co~nection-effective 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 may be, if desired or required,
associated with an appropriate flux. 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 sub-
strate having exterior dimensions only slightly smaller
than the inner dimensions of the sleeve. The quantity of
solder is preferably held merely by its engagement with
the conductor, without the ~eed 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
anv case contact the sleeve, if desired.
The quantity of solder may have any suitable form
and may be maintained on the conductor in any sui~able
manner. Thus, for example, ~e 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.
r
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 mc~nner about the conductor and, whatever
the shape of the quantity of solder the latter may, if
appropriate, be crimped onto the conductor. If desired or
required, the quantity of solder may include one or more
outwardly extending portions, for example a pair of lugs,
for enhancing the enchorage of the solder, and thus the
conductor, in the sleeve; during manufacture o~ ~he article
the sle~ve may be partially recovered into engagement with
one or more such outwardly extending portions.
The conductor a~lso is advantageously so positioned
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. Pre-
- ferably the portion of the conductor wikhin the sleeve
extends in a direction which is su~stantially parallel to the
axis of the sleeve, and advantageously the insulated
portion(s) of the conductor within the sleeve a~ut(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
2~ any suitable manner. It should be understood that
provided the sleeve and conductor do not become sep~rated
from one another during normal handling, it is not
essential that the various components be rigidly fixed
:` i
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relative to each other: some slight relative movement
may be permissible.
Advantageously the conduct:or 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 infus:ible 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
~usible at that temperature such that on installation of
the article the fused insert material may assist in prov-
iding 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 the conductor in the sleeve.
A further method by which the conductor may be retain-
ed in the sleeve comprises partial recovery o~ the sleeve
about the conductor. ~his method may, if desired, be
com~ined with the method described above wherein the
conductor is held by one or more inserts and/or with any
other methocl.
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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. Advant-
ageously the portion of the conductor which is to take part
in making the electrical connection is not the extreme end
portion, and a conduc~or 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
10 point in the region of the end of the conductor. ~hus, for
example, the short length of insulation may be moved longitud-
- inaliy over the conductor until a part only of the insulation
extends beyond the end of the conductor, if desired the long-
itudinally extending part of the short length of insulation
15 may be cut off so that the conductor and the separate length
of insulation are conterminous. When the conductor is strand-
ed, a short length of insulation remaining on the extreme end
portion of the cQpductor may assist in maintaining the strands
in the stripped portion close together and relatively straight.
20 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 ~uantity of solder,
each insert advantageously contacts an insulated portion of
the conductor. During manufacture an insulated end portion
25 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
~L~L3~ 4
need to hold the conductor in the desired place, this is
particularly advantageous when the sleeve is positioned
vertically during manufacture.
The heat-shrinkable sleeve used in accordance with the
invention is a sleeve at least part of which w-ll shxink on
the application of heat and may ~omprise any material, advan-
tageously an electrically insulating material, whi~h may be
converted to or maintained in a he~t-shrinkable form. Examples
of suitable materials are given in, for example, U.S. Patent
10 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 compris-
ing two or more layers is used, the inner layer(s) need not
15 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 e~truded as such, or may be formed
from a sheet of material (which may if desired be heat-shrink-
20 able) opposite edges of the sheet being joined in any suitablemanner, 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 thermo-
plastic material and a heat-activatable crosslinking agent
25 (see for example U.S. Patent Specifications ~o. 3,891,490 and
3,927,233 and British Patent Specification ~o. 1,512,727) to
form the sleeve. If desired, the opposite edges of the sheet
may
~3~ f~
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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 ~rom a sheet of material, the sheet may if desired
be shaped to hold the quantity of solder before forma-
tion of the sleeve. Heat-shrinkability may, if necessary,
be imparted to a sleeve by any su~itable method.
The heat-shrinkable sleeve may havP any desired
shape. One method by which a desired shaped may be
imparted comprises partial recovery of the sleeve round
one or more appropriately shaped mandrels. Where one
or more inserts are present, these 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 sleeve may be open at one or both ends and
mav if aesired be provided with a quantity of fusible
material (for example fusible polymeric material~-or
other sealing material between the solder and the or
_ach open end. Where the sleeve contains a fusible
insert, this may form the quantity of fusible material.
The fusible material may act as Udam'' 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 a'_ the end(s~ of the
sleeve. Thus, the sleeve can fo_ce fused fusible
~p
material into close contact with a conductor received in
the open end of the sleeve to provide a reliable seal.
Alternatively, the sleeve ancl the fused fusible material
could cooperate to produce a seal even at an open end
that does not in use receive a substrate.
In a preferred embocliment 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, ~e first ring being positioned
between the uninsulated portion o~ 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 invention also provides a method of making an
electrical connection which comp ises positioning an
article according to the invention over a substrate and
heating to cause shrinXage of the sleeve and fusing of
the solder to make an electrical connection between the
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electrical conductor and the substrate. Advantageously,
the substrate is the outer conductor of a coaxial cable.
The article of the invention may readily be manufactur-
ed without the use of complicated tooling. As the article
comprises a preinstalled conducl:or and quantity of solder,
the connection of an earth condllctor to, for example, the
outer conductor of a coaxial cable may be effected merely
by inserting the outer conductor in the article and heatin~:
the article may thus readily be installed by an automatic
10 process. Furthermore, the quantity of solder appropriate
to a particular use may be selected during manufacture of
the sleeve, ~nd the fact that the solder is o~ the conductor
.
and positioned eccentrically in the sleeve makes it possible
to obtain a very good localized solder joint without the
15 use of excess solder which may after fusing be present in
undesired locations. Thus, for example, where an earth
conductor is connected to the outer conductor of a coaxial
cable, the use o~f the article of the invention may result
in there being substantially equal amounts of solder on the
20 earth conductor and on the outer conductor in the final
assembly. Furthermore, because it is necessary to fuse only
the amount o 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
25 make it possihle,if desired, to use solder of a
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higher melting point than would be ~ossible if for example
a complete ring o~ solder were used.
Trhe above situation is in contrast 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 betwePn the earth corductor and the outer
conductor~, so tha~ 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 ~o. 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 exam~le only, with
reference to the accompanying drawing in which
~igure 1 is a perspective view of one embodiment
of the invention and
- 14 -
Figures 2 to 4 are pers~ective views showing
electrical conductors for use in the
article of the invention having
quantities of solder of different
shapes thereon.
Referring now to the drawings, a heat-shrinkable
sleeve 1 has open ends 2 and 3 respectively. An insulated
conductor indicated generally by the reference numeral 4
having an uninsulated portion 5 within the sleeve extends
from ~he open end 2 of the sleeve. The end of the
conductor 4 is insula~ed by a sho~t length of insulation
6, and insulation 7 is present on the portion of the
conductor 4 between the uninsulated ~ortion 5 and the open
end 2 of the sleeve. A ball 8 of solder surrounds part of
the uninsulated portion ~ of the conductor 4.
The portion of the conductor 4 within the sleeve
1 extends in a direction which is generally parallel to the
axis of the sleeve with the portions of insulation 6 and 7
(and the solder ball 8~ contacting the inner surface of the
sleeve. The conductor 4 is retained in position in the
sleeve by cooperation between the sleeve and two rings of
fusible material, 9 and 10 respectively. The rin~ 9-is
positioned between the uninsulated portion 5 of the
conductor and the open end 2 of the sleeve, a portion of
insulation 7 being sandwiched between the outer surface
of the ring 9 and the inner surface of the sleeve 1.
,~.; ;. .
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Similarly, a portion of insulation 6 is sandwiched
between the outer surface of the ring 10, which is
positioned between the unin~ulated portion 5 of the
conductor and the open end 3 of the sleeve, and the inner
surface of t~e sleeve. The sleeve has been partially
recovered from a diameter greater than that shown, to
fix the conductor 4 and the rings 9 and 10 in position so
that they do not mo~e significantly with respect to each
other or to the sleeve 1.
In the embodiment of the invention shown in
Fi~re 1, 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
~uter conductor is adjacent to solder ball 8 an~ the
assembly may then be heated to cause the sleeve to shrink
and ~e solder ball 8 and fusible rings 9 and 10 to ~use so
that a soldered connection is made between the uninsulated
portion 5 of the conductor 4 and the outer conductor of the
coaxial cable and an enviromental seal is made, if desired.
When, as shown in the drawings, the sleeve 1 is transparent
the soldered connection may readily be inspected, but
where such visual inspection is not necessary use of a
- 16 -
transparent material is not essential.
Figures 2 to 4 shows quant:ies of solder of different
shapes on an uninsulated portio!n 5 of the conductor 4. The
quantity of solder 11 shown in :Figure 2 is formed by crimp-
ing a strip of solder around the portion 5, the resultantquantity of solder being in cross-section, in the form of a
compressed 'C'. Thus, in a cross-section through solder 11,
the centre portion 12 and end portions 13 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 14 of solder each of
which has, in cross-section, a lateral ~xtent greater
than the thickness of the solder strip.
Figure 3 shows a quantity of solder in the form of a
ball 15 provided with a pair of diametrically opposed
outwardly extending lugs 16 which may, if the sleeve is
partially recovered into engagement with at least one of
them, enhance the anchorage of the conductor 4 in the
sleeve 1. The quantity of solder 17 shown in Figure 4 is
substantially triangular in cross-section, and has a slit
18 therein whereby it is open in cross-section so that it
can be forced onto the uninsulated portion 5 of the conduc-
tor 4, in the case of a stranded conductor-~his step may .
be facilitat~!d by movement_. .. .... _ ~ . _
- 17 -
of the strands relative 'o one another. The slit 18
communicates with a central hole 19 in the solder 17, the
dimensions of the hole being such that the solder ~7 is
held tightly on the conductor.
The quantitie~ of solder shown in Figures 2 to
4 may if desired be used in an article as shown in Figure
1 in place of the solder ball 8 used therein, or may be
used in any o~her article constructed in accordance with
the invention. One or both of the outwardly extending
1o portions 14 in Figure 2 and one or more of the apices of
the triangle which is the cross-section through the qusntity
of ~older 17 in Figure 4 may if desired act in the same
manner as the lugs 16 in Figure 3, namely to enhance the
anchorage of the solder, and hence the anchorage of the
conductor ~ in the sleeve. One situation where such
enhancement may be desirable is where the short length of
insulation 6 in Figure 1 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 9 in Figure 1,
ring 10 being absent).
.
An article according to the invention may if desired
comprise more than one preinstalled elongate electrical
conductor having a quantity of solder thereon.
Ex~nples of elongate electrical conductors which
may be used in the article of the invention are earth
- 17a -
conductors and electrically conductive pins, for example
tenminal pins.
It is to be understo~d that a sleeve which has a
substantially constant cross-section throughout its length
may have an additional portioll, for example, a~ end portion,
of a different cross-sectiona:L shape and/or size provided
that an appreciable part of the inner circumference of the
additional portion i5 spaced to a significant extent from
the conductor, that is, provided the additional portion is
not recoveEed into close contact with the conductor.
. .. _ . .. .. .. . . .. .... . ..... . . . .....
