Electrical connectors and methods of connecting electrical conductors

An electrical connector device for electrical conductors comprising a conducting ferrule receiving the leads from two insulated conductors and a heat shrinkable plastic tube surrounding the ferrule and extending past the ends of the ferrule, the tube having a normally dry, heat activated adhesive coated on the interior thereof, which tube is heated and thereby shrunk and hermetically bonded to the exterior of the ferrule and the insulation on the conductors. In certain situations an additional insulating layer is interposed between the tube and the ferrule. An electrical conductor, usable in the electrical connector device, comprises an insulated electrical wire, a ferrule receiving a lead from the wire, and a heat shrinkable plastic tube having normally dry, heat activated adhesive coated on the interior thereof, which tube is heated and thereby shrunk and hermetically bonded to both the ferrule and the wire insulation.

The present invention relates to electrical connectors for insulated 
electrical conductors and methods of connecting these electrical 
conductors. More specifically, the present invention relates to connecting 
electrical conductors by means of a metallic ferrule and a heat shrinkable 
plastic tube having normally dry, heat activated adhesive coated on the 
interior thereof for securing the electrical conductors to the ferrule and 
for providing a moisture seal therebetween. 
There have been numerous attempts in the prior art to provide an effective 
electrical connector for insulated electrical conductors; however, these 
prior art attempts have numerous deficiencies. Many of them require a 
complicated sequence of steps in order to make the connection which is 
time consuming and which requires a certain degree of skill and 
manipulative expertise. Also, many of the prior art devices are bulky and 
heavy which results in difficulty in maneuvering of the electrical 
connector in the usually cramped area in which it is used. Of even more 
significance many of the prior art devices do not provide adequate strain 
relief so that flexing, pulling and twisting of the electrical conductors 
results in failure of the electrical connector. Of similar importance is 
the failure of the prior art devices to provide adequate moisture sealing 
of the connection which results in failure of the connection and the 
requirement of replacing such connection. 
In addition, many of the prior art devices require a very accurate location 
of the insulation in relation to the connection which, if not so provided, 
results in poor insulation protection and high incidence of electrical 
failure. Finally, many of the prior art devices that provide some moisture 
seal and strain relief are difficult or impossible to disconnect easily, 
so disconnection is usually accomplished by severing of the electrical 
conductor, resulting in waste. 
Accordingly, it is an object of the present invention to provide an 
electrical connector which is quick and easy to install without a 
complicated sequence of steps. 
Another object is to provide an electrical connector having a low profile 
and a light weight. 
Another object is to provide an electrical connector which is highly strain 
relieved and can resist flexing, pulling and twisting of the electrical 
conductors without failure of the connection. 
Another object is to provide an electrical connector which is hermetically 
sealed to prevent moisture contamination of the connection and to prevent 
failure therefrom. 
Another object is to provide an electrical connector which is highly 
insulated and does not require a high degree of accuracy with regard to 
aligning of the insulation protection over the connector. 
Another object is to provide an electrical connector which does not require 
a special crimping tool. 
Another object is to provide an electrical connector which is easy to 
disconnect and whose conductors are reusable. 
Another object is to provide methods of connecting electrical conductors 
which are simple and require little time or skill to accomplish. 
SUMMARY OF THE INVENTION 
The foregoing objects are attained by providing a device for connecting two 
insulated electrical conductors, each of the conductors including a 
conducting portion surrounded by an insulating portion with the conducting 
portion having a lead extending past the end of the insulating portion, 
wherein the combination comprises a conductive member having a bore at 
each end and an exterior surface, each of the leads being at least 
partially receiveable in one of said bores in a conducting relationship 
with said conductive member; and means, coupled to said conductive member 
exterior surface, for securing the conductors to said conductive member, 
said means comprising a first heat shrinkable plastic tubular portion 
extending past one end of said conductive member and receiving therein a 
part of the insulating portion of the first electrical conductor, and 
normally dry, heat activated adhesive coated on the interior surface of 
said first tubular portion, said means further comprising a second heat 
shrinkable plastic tubular portion extending past the other end of said 
conductive member and receiving therein a part of the insulating portion 
of the second electrical conductor, and normally dry, heat activated 
adhesive coated on the interior surface of said second tubular portion, 
each of said tubular portions initially having an inner diameter greater 
than the outer diameter of the part of the insulating portion received 
therein and then being coupled in a sealing relationship with the 
insulating portion of a respective one of the electrical conductors by 
heating said tubular portion to thereby shrink said tubular portion into 
an engaging relationship with the insulating portion and to thereby 
activate said adhesive coated thereon to hermetically bond the tubular 
portion to the insulating portion. 
More specifically, as shown in FIGS. 1-3, the electrical connector 
comprises a metallic, malleable ferrule surrounded by a heat shrinkable 
plastic tube having normally dry, heat activated adhesive coated on the 
interior surface of the tube. The central portion of the tube is first 
heated to thereby shrink and adhere the central portion to the exterior 
surface of the ferrule and then the two electrical conductors are 
maneuvered into the ferrule and the connector is crimped in the ferrule 
area containing the leads of the electrical conductors. The two ends of 
the tube extending past the ferrule are heated to thereby shrink and 
hermetically bond these ends to the insulation of the electrical 
conductors. 
As shown in FIGS. 4-6, an electrical conductor, usable in the electrical 
connectors shown in FIGS. 7-10, comprises an insulated electrical wire, a 
ferrule receiving a lead from the wire, and a heat shrinkable plastic tube 
having a normally dry, heat activated adhesive coated on the interior 
thereof, which tube is heated and thereby shrunk and hermetically bonded 
to both the ferrule and the wire insulation. 
As shown in FIGS. 7 and 8, the electrical connector is the same as that 
shown in FIGS. 1-3 except an insulating layer is interposed on the 
exterior of the ferrule, the inner diameter of the ferrule is larger for 
receiving the larger diameter electrical conductor of FIGS. 4-6, and 
protuberances are provided in the ferrule for releaseably securing the 
leads of the electrical conductors by reception thereof in the 
indentations therein. 
As shown in FIGS. 9 and 10 the electrical connector has two heat shrinkable 
plastic tubes received on opposite ends of a ferrule with one of the tubes 
receiving an electrical conductor which is a conventional insulated 
electrical wire and the other of the tubes receiving an electrical 
conductor in accordance with FIGS. 4-6 hereof. The electrical wire is 
crimped to the ferrule while the electrical conductor shown in FIGS. 4-6 
is received by the ferrule by means of the protuberance-indentation 
releasable connection. 
Since the connectors disclosed herein basically comprise a metal ferrule 
and heat shrinkable plastic tubing having a normally dry, heat activated 
adhesive coated thereon, the connection is easily and quickly installed 
without any complicated steps in the sequence of connection. Similarly, 
the connection has a low profile and is light in weight. 
Since the heat activated adhesive on the tubes forms a hermetic bond to the 
insulation of the connected electrical conductors, this connection is 
moisture sealed and provides a high degree of strained relief. When 
necessary, the electrical conductor is crimped in the electrical 
connector; however, this is accomplished without a special crimping tool. 
Since the leads of the electrical conductors are received in the metallic 
ferrule, accurate positioning is assured relative to the insulation 
provided by the heat shrinkable plastic tubing. In addition, this plastic 
tubing provides a complete insulation for the connection, and this 
insulation can be easily reinforced where necessary by adding an extra 
insulating layer to the metal ferrule between the ferrule and the heat 
shrinkable plastic tube. Finally, as described in more detail hereinafter, 
the connections shown in FIGS. 7-10 can be dismantled in a simple manner 
by notching the heat shrinkable plastic tube, exposing the tube to 
additional heating to split and shrink it and removing the split tube, and 
then reassembling the connector with a new tube. 
Other objects, advantages and salient features of the present invention 
will become apparent from the following detailed description, which, taken 
in conjunction with the annexed drawings, discloses preferred embodiments 
of the present invention.

DESCRIPTION OF FIGS. 1-3 
Referring now to the drawings in further detail, as shown in FIG. 1 the 
electrical connector 10 in accordance with the present invention comprises 
a conductive member 12, a heat shrinkable plastic tube 14 and normally 
dry, heat activated adhesive 16 coated on the interior surface of the tube 
14. 
The conductive member 12 is formed from a metallic, malleable material, 
such as copper, and is substantially tubular having a central bore 18 
extending completely therethrough such that the conductive member 12 has 
opposite open ends 20 and 22. While this conductive member 12 is shown as 
being tubular, it is contemplated that the member can have a solid center 
part with two opposite blind bores extending from opposite sides or can 
have a longitudinal slit running from end to end in its wall. 
The heat shrinkable plastic or polymeric material forming tube 14 has the 
property of an elastic memory and as such is dimensionally heat unstable 
and may be caused to change shape and/or dimension simply by the 
application of heat. Such elastic memory may be imparted to polymeric 
materials by first extruding or otherwise molding the polymer into a 
desired shape. The polymer is then cross linked or given the properties of 
a cross-linked material by exposure to high energy radiation, e.g., a high 
energy electron beam, initiation of cross linking by exposure to ultra 
violet radiation, or by chemical means, e.g., peroxides when polyolefins 
are used. The cross-linked polymeric material is then heated and deformed 
to the required shape and/or dimension and then locked in the deformed 
condition by quenching or other suitable cooling or, in the alternative, 
the same process can be accomplished at room temperature by using greater 
force to deform the polymer. In any event, the deformed material will 
retain its shape almost indefinitely until exposed to a temperature 
sufficient to cause recovery, e.g., approximately 250.degree. F. in the 
case of polyethylene. Among the polymers which may be so processed are 
polyolefins such as polyethylene and polypropylene, polyamides, 
polyurethanes, polyvinylchloride, polyvinylidenefluoride, copolymers of 
ethylene and an alkyl acrylate, and elastomeric materials such as 
elastomeric polyurethanes. The property of elastic memory may also be 
imparted to materials having the properties of cross-linked polymers such 
as polytetrafluorethylene and very high molecular weight polyolefins or 
vinyl polymers such as polyvinylchloride. 
The layer of adhesive 16 coated on the interior surface of the heat 
shrinkable plastic tube 14 should be normally dry at normal room 
temperatures, but readily rendered tacky upon heating above such 
temperatures, e.g., by exposure to a lighted match. The adhesive should 
also lose its tacky quality when the adhesive is cooled. One such adhesive 
which is suitable is a 10% solution of chlorinated rubber (Tornesite). 
Another is a 10% solution of cyclised rubber in gasoline. A third 
adhesive, which is especially suited for use with a heat shrinkable 
polyvinylchloride tube is the product known commercially as "Casco-Bond 
SA-5461" which is a synthetic resin solution having a ketone odor when wet 
and a normal viscosity of 4000-6000 ccs., Brookfield, manufactured by 
Borden, Inc./Chemical Division, New York, New York. 
Referring again to FIG. 1, the heat shrinkable plastic tube 14 is comprised 
of a central portion 24 extending from one end to the other end of the 
conductive member 12, a first portion 26 extending from one end of the 
central portion past an end of the conductive member, and a second portion 
28 extending from the other end of the central portion past the other end 
of the conductive member. 
Initially, the inner diameter of the central portion 24 is larger than the 
outer diameter of the conductive member 12. However, this central portion 
is coupled to the exterior surface of the conductive member by being 
heated to a sufficient temperature to thereby shrink the central portion 
into an engaging relationship with the conductive member exterior surface 
and to thereby activate the adhesive to hermetically bond the central 
portion to the conductive member exterior surface. This is the condition 
shown in FIG. 1 in which relative movement between these members is 
resisted by the adhesive bond and they are moisture sealed. 
As also shown in FIG. 1, a first electrical conductor 30 and a second 
electrical conductor 32 are about to be inserted into the conductive 
member 12. The first electrical conductor 30 is a conventional insulated 
electrical wire formed by a conducting portion 34 surrounded by an 
insulating portion 36 with the conducting portion having a lead 38 
extending past the end of the insulating portion. The conducting portion 
34 is made of a plurality of strands of material, such as copper, and the 
insulating portion 36 is formed from rubber or plastic material engagingly 
surrounding the conducting portion. 
The second electrical conductor 32 is similarly formed and comprises a 
conducting portion 40, an insulating portion 42 and a lead 44. 
Referring now to FIG. 2, the leads 38 and 44 of electrical conductors 30 
and 32 have been received in respective opposite ends 20 and 22 of the 
conductive member 12 so that the end of the insulating portions for each 
of the electrical conductors directly abuts the ends of the conductive 
member. In this position, the leads 38 and 44 extend inwardly into the 
conductive member a distance for each which is slightly less than half the 
longitudinal length of the conductive member. This is preferably the case; 
however, the leads could be shortened somewhat as long as they extend 
somewhat into the conductive member so that they can be crimped, as 
described in more detail hereinafter, or the leads could each be longer 
than one half the longitudinal length of the conductive member in which 
case the end of the insulating portion for the respective electrical 
conductor would not abut the end of the conductive member. In this latter 
case however the insulating portion of the electrical conductor should be 
at least partially received within the first portion 26 or the second 
portion 28 of the heat shrinkable plastic tube 14. In any event, the 
positioning shown in FIG. 2 is the most preferable. 
Thus, once the leads are received in the conductive members 12, a 
conventional crimping tool is maneuvered around the outside of the heat 
shrinkable plastic tube 14 in the area containing the lead 38 and the heat 
shrinkable plastic tube, the adhesive 16, the conductive member 12 and the 
lead 38 are all subjected to a crimping operation resulting in the crimp 
generally shown at 46. A similar crimp generally shown as 48 for lead 44 
is additionally accomplished. While the outer diameter of the leads 38 and 
44 would most likely be chosen so that they are substantially equal to the 
inner diameter of the conductive member 12 so that a conducting 
relationship results between the conductive member and the leads, the 
crimping operation is deemed desirable in order to assure a conductive 
relationship therebetween and to add resistance to an axial pull of the 
electrical conductors relative to the conductive member 12. 
Referring now to FIG. 3, the completed electrical connector is shown 
therein. Initially, the interior diameters of the first portion 26 and the 
second portion 28 of tube 14 are larger than the outer diameter of the 
part of the insulating portions 36 and 42 of electrical conductors 30 and 
32 received in these portions of the tubes and then are coupled in a 
sealing relationship with the insulating portions of the respective ones 
of the electrical conductors. This is accomplished by heating the first 
and second portions of tube 14 to thereby shrink these portions into an 
engaging relationship with the insulating portion and to thereby activate 
the adhesive coated thereon to hermetically bond the first and second 
portions to the insulating portions of the respective ones of the 
electrical conductors 30 and 32. By "hermetically bond" it is meant that 
the connection between these elements provides a moisture seal and 
prevents relative movement therebetween. 
By so forming the electrical connector 10, a moisture proof seal is 
provided by means of the heat activated adhesive 16 and a highly strain 
relieved connection results by the coupling of the heat shrinkable plastic 
tube 14, via the adhesive, to the insulating portions of the electrical 
conductors and in addition to the conductive member 12. This connector, as 
clearly shown in FIG. 3, is low in profile and light in weight and is easy 
to assemble. 
DESCRIPTION OF FIGS. 4-6 
Referring now to FIG. 4, an electrical conductor 50 is shown which is 
usable with the electrical connectors to be described hereinafter in FIGS. 
7-10. This electrical conductor 50 is for use with a conventional 
electrical wire 52 formed of a conducting portion 54, a tubular insulating 
portion 56 surrounding the conducting portion and a lead 58 on the 
conducting portion extending past an end of the insulating portion. This 
electrical wire 52 is formed from materials similar to that forming 
electrical conductors 30 and 32 referred to above. 
The electrical conductor 50 comprises a metallic, malleable, tubular 
ferrule 60 having a central bore 62 and an open end 64, a heat shrinkable 
plastic tube 66 and normally dry, heat activated adhesive 68 coated on the 
interior surface of the heat shrinkable plastic tube 66. 
The inner diameter of the heat shrinkable plastic tube 66 is initially 
greater than the outer diameters of both the ferrule 60 and the insulating 
portion 56 of electrical wire 52. 
As shown in FIG. 4, a portion of the ferrule 60 is received in a portion of 
the tube 66 and that tube has been heated and thereby shrunk into an 
engaging relationship with the exterior surface of the ferrule and the 
adhesive coated on the interior surface of the tube has been activated to 
hermetically bond the tube to the exterior surface of the ferrule. 
Referring now to FIG. 5, the electrical wire 52 has been maneuvered so that 
lead 58 is received via open end 64 into the central bore 62 of the 
ferrule 60. In the position shown the end of the insulating portion 56 
abuts the end of the ferrule 60. In this position, at least a portion of 
the insulating portion 56 is received within the unshrunk portion of the 
plastic tube 66 and a crimping operation can be accomplished on lead 58. 
Thus, a crimp generally designated as 70 is provided by utilizing a 
conventional crimping tool on the heat shrinkable plastic tube 66, the 
heat activated adhesive 68, the ferrule 60 and the lead 58. Such a crimp 
assures excellent conductive contact between the lead and ferrule. 
Referring to FIG. 6, the completed electrical conductor 50 is shown in 
which the portion of the heat shrinkable plastic tube 66 receiving a 
portion of the insulating portion 56 has now been sealed thereto. This is 
accomplished by heating the plastic tube in that area to thereby shrink 
the tube into an engaging relationship with the insulating portion and to 
thereby activate the adhesive to hermetically bond the plastic tube to the 
insulating portion. 
As shown in FIGS. 4, 5 and 6, the ferrule 60 has a circumferential 
indentation 72 adjacent an end thereof spaced from the heat shrinkable 
plastic tube 66, the purpose of which shall be discussed hereinafter. 
Referring again to FIG. 6, the electrical conductor 50 is shown in its 
final, usuable form in which the combination of ferrule 60 and lead 58 
provides a lead for the electrical conductor 50 and the combination of the 
insulating portion 56 and heat shrinkable plastic tube 66 forms a overall 
insulating portion for the electrical conductor 50. 
DESCRIPTION OF FIGS. 7-8 
Referring now to FIGS. 7 and 8, a second embodiment of the present 
invention is shown therein which is similar to that shown in FIGS. 1-3; 
however, an insulating layer 74 engages the exterior of the ferrule and 
contacts the adhesive coated on the interior surface of the heat 
shrinkable plastic tube, and in addition the ferrule has two protuberances 
extending inwardly from the wall thereof into the central bore. In 
addition, rather than utilizing the electrical conductors 30 and 32 
described above regarding FIGS. 1-3, the electrical conductor 50 described 
above regarding FIGS. 4-6 is utilized. 
In FIGS. 7 and 8, those parts which are shown which are the same as those 
described regarding FIGS. 1-6 are given the same character numerals for 
ease of reference, and these parts are essentially the same except that 
their diameters are slightly larger in order to receive the slightly 
larger ferrule 60 and heat shrinkable plastic tube 66 discussed above 
regarding FIGS. 4-6. 
Thus, specifically referring to FIG. 7, the conductive member 76 is formed 
from a metallic ferrule 78 and the insulating layer 74 engaging the 
exterior of the ferrule 78 and thereby forming the exterior surface 
thereof. 
The ferrule 78 has a central bore 80 and two opposite open ends 82 and 84. 
Two protuberances 86 and 88 extend inwardly from the interior surface of 
the wall of the ferrule 78 into the bore 80 and are substantially equally 
spaced along the length of the bore. 
The insulating layer 74 is either frictionally fit over the exterior of the 
ferrule 78 or is bonded thereto and can be formed on nylon, plastic, 
rubber, Mylar or insulating tape. This layer also extends past the open 
ends 82 and 84 of the ferrule 78 forming tubular cavities 90 and 92 at 
respective ends of the ferrule. 
As shown in FIG. 7, first the insulating layer 74 is engaged with the 
exterior of ferrule 78 and then the heat shrinkable plastic tube 14 
central portion 24 is heated to thereby shrink the central portion into an 
engaging relationship with the insulating layer 74 and to thereby activate 
the adhesive coated thereon to hermetically bond the heat shrinkable 
plastic tube to the insulating layer. 
As shown in FIG. 7, two electrical conductors 50 are about to be received 
in ferrule 78. Preferably, the outside diameter of ferrule 60 is 
substantially equal to the inside diameter of ferrule 78 so that there is 
a frictional fit therebetween providing a conducting relationship 
therebetween. Moreover, preferably the length of the exposed part of 
ferrule 60 is somewhat less than half the length of ferrule 78. In 
addition, preferably the outside diameter of heat shrinkable tube 66 is 
slightly less than the inside diameter of cavities 90 and 92 so that tube 
66 can be received in each of these cavities. Finally, the inside diameter 
of portions 26 and 28 of the heat shrinkable plastic tube 14 are initially 
larger than the outside diameters of the heat shrinkable plastic tubes 66 
on the electrical conductors 50 so that tubes 66 are receivable in 
unshrunk portions 26 and 28. 
Referring now to FIG. 8, the two electrical conductors 50 have had their 
ferrules 60, i.e., their leads, inserted into respective ends 82 and 84 of 
ferrule 78 a sufficient distance such that protuberances 86 and 88 are 
received in indentations 72. Thus, there is a conducting relationship 
between ferrules 60 and the ferrule 78 because of the frictional fit 
therebetween and also because of the contact of the protuberances with the 
areas of ferrules 60 adjacent indentations 72. The provision of the 
protuberances and indentations also provide some additional strain relief 
to the connection. 
In addition to the ferrules 60 being received in ferrule 78, portions of 
the heat shrinkable plastic tubes 66 on the two electrical conductors 50 
are received in the tubular cavities 90 and 92 so that the insulating 
layer 74 covers that portion of the ferrules 60 extending out of the 
ferrule 78. It should be pointed out that while there is a space shown in 
FIG. 8 between the ends of heat shrinkable plastic tubes 66 and the ends 
82 and 84 of ferrule 78, the ends of heat shrinkable plastic tubes 66 can 
abut these ends 82 and 84 of the ferrule 78 is made longer or the ferrules 
60 are made shorter. 
As shown in FIG. 8, portions 26 and 28 are in a sealing relationship with 
heat shrinkable plastic tubes 66 on the two electrical conductors 50 
thereby completing the formation of the electrical connector. This is 
accomplished by heating the portions 26 and 28 of the heat shrinkable 
plastic tube 14 while the heat shrinkable plastic tubes 66 are received in 
these portions to thereby shrink these portions into an engaging 
relationship with the exterior ssurfaces of tubes 66 and to thereby 
activate the adhesive coated on the interior surfaces of these portions to 
hermetically bond these portions to respective ones of the heat shrinkable 
plastic tubes 66. 
Because of the use of the electrical conductors 50 shown and described 
above regarding FIGS. 4-6, the electrical connectors shown in FIGS. 7 and 
8 can be reused. That is, the connection formed between the two electrical 
conductors 50 and the ferrule 78 can be disconnected and then reconnected. 
This is accomplished by initially providing a longitudinal notch along the 
central portion 24 of the heat shrinkable plastic tube 14 and then 
reheating the tube. This reheating causes a further shrinking of the tube 
resulting in an extension of the initial notching thereof into a complete 
longitudinal slit of the wall of the heat shrinkable plastic tube 14 from 
one end to the other. Such heating also causes the heat activated adhesive 
to become fluid, thereby lubricating the movement of the tube 14 as it 
splits itself apart by further shrinking. Once the tube 14 is completely 
split it can be removed from the connection thereof with the insulating 
layer 74 and heat shrinkable tubes 66 on electrical conductors 50. Then 
these electrical conductors 50 can be removed from the ferrule 78 which 
allows for components or parts at the other end of conductors 50 to be 
separated or changed. 
In order to reconnect the electrical conductors 50, a new heat shrinkable 
plastic tube coated on the interior thereof with normally dry, heat 
activated adhesive is maneuvered over the insulating layer 74 with two 
ends extending outwardly therefrom and the operation described above 
regarding FIGS. 7 and 8 is repeated. 
Since an additional insulating layer 74 is utilized in this embodiment, 
high insulation is provided and, if this embodiment is crimped, it will 
withstand potential insulation loss due to possible cutting by the 
crimping tool. This insulating layer 74 can also be utilized in the FIGS. 
1-3 embodiment in which conductors 30 and 32 are connected. 
DESCRIPTION OF FIGS. 9 and 10 
Referring now to FIGS. 9 and 10, a third embodiment of the present 
invention is shown in which a ferrule has an insulating layer engaging the 
outer surface thereof and two separate heat shrinkable plastic tubes are 
coupled to the ferrule so that the electrical connector formed thereby can 
receive an electrical conductor in the form of a conventional insulated 
electrical wire at one end and an electrical conductor such as that 
disclosed above in FIGS. 4-6 on the other end. Moreover, that portion of 
the electrical connector receiving the electrical conductor of FIGS. 4-6 
can easily have the electrical conductor removed therefrom and replaced as 
desired. 
Referring specifically to FIG. 9, there is shown therein a conductive 
member 94 comprised of a ferrule 96 and an insulating layer 98, a first 
heat shrinkable plastic tube 100 having a normally dry, heat activated 
adhesive 102 coated on the interior surface thereof, and a second heat 
shrinkable plastic tube 104 coated on the interior surface thereof by a 
normally dry, heat activated adhesive 106. 
The ferrule 96 is formed of malleable metal and comprises a first part 108 
having an open end 110 and a second part 112 with an open end 114, the 
ferrule having a hollow interior and a protuberance 116 extending inwardly 
from the wall of the second part 112 adjacent the open end 114. As shown 
in FIG. 9, the inner diameter and the outer diameter of the second part 
112 is larger than the respective inner and outer diameters of the first 
part 108. 
The insulating layer 98 is formed from the same material as that described 
above regarding FIGS. 7 and 8 and is in an engaging relationship with the 
exterior of ferrule 96, thereby forming the exterior surface thereof, and 
extending past the open end 114 of the second part 112 forming a tubular 
cavity 118. 
The first heat shrinkable plastic tube 100 has a base portion 120 and a 
tubular portion 122. The base portion 120 initially has an inner diameter 
larger than the outer diameter of that portion of the insulating layer 98 
surrounding first part 108 of the ferrule 96 but has been heated so as to 
be in a sealing relationship with the insulating layer. This is 
accomplished on such heating by shrinking of the base portion 120 into an 
engaging relationship with the insulating layer 98 and by activating the 
heat activated adhesive to hermetically bond the base portion 120 to the 
insulating layer 98. 
Similarly, the second heat shrinkable plastic tube 104 is comprised of a 
base portion 124 and a tubular portion 126. The base portion 124 initially 
has an inner diameter larger than the insulating layer 98 covering the 
second part 112 of ferrule 96 but has been heated to thereby shrink the 
base portion 124 into an engaging relationship with the insulating layer 
98 and to thereby activate the adhesive thereon to hermetically bond the 
base portion 124 to the insulating layer 98. 
As seen in FIG. 9, the tubular portion 122 of the first tube 100 extends 
past open end 110 of ferrule 96 and initially has an inner diameter 
greater than the outer diameter of the insulating portion 42 on the 
electrical conductor 32 having a conducting portion 40 and a lead 44. 
Similarly, the inner diameter of the tubular portion 126 of the second tube 
104 initially is larger than the outer diameter of heat shrinkable plastic 
tube 66 on the electrical conductor 50 having a lead in the form of 
ferrule 60. 
Referring now to FIG. 10, electrical conductor 32 has been maneuvered so 
that lead 44 is passed through open end 110 in ferrule 96 and is received 
therein in a conducting relationship with the end of insulating portion 42 
abutting the end of ferrule 96. Furthermore, a crimping operation has 
taken place forming a crimp generally designated as 128 by utilizing a 
conventional crimping tool on base portion 120, adhesive 102, insulating 
layer 98, the first part 108 of ferrule 96 and lead 44. Moreover, the 
tubular portion 122 has been heated to provide a sealing connection with 
insulating portion 42 of electrical conductor 32. That is, the tubular 
portion 122 has been heated to thereby shrink that portion into an 
engaging relationship with the exterior surface of insulating portion 42 
and to thereby activate the adhesive thereon to hermetically bond the 
tubular portion 122 to insulating portion 32. 
In addition, ferrule 60 on electrical conductor 50 has been inserted in 
open end 114 of the second part 112 of ferrule 96 so that protuberance 116 
is received in indentation 72 in the ferrule 60. By so maneuvering ferrule 
60 into ferrule 96 there is a conducting relationship therebetween. 
Moreover, as shown in FIG. 10 a portion of the heat shrinkable plastic tube 
66 on electrical conductor 50 is received in tubular cavity 118 so that 
the insulating layer 98 protects any part of ferrule 60 extending out of 
ferrule 96. Although the end of heat shrinkable plastic tube 66 is not 
shown in FIG. 10 abutting the end of ferrule 96, this can be done if 
desired, with a concomitant movement of protuberance 116 further inward 
along ferrule 96 or movement of indentation 72 toward heat shrinkable 
plastic tube 66. 
Finally, as shown in FIG. 10, the tubular portion 126 of the second heat 
shrinkable plastic tube 104 has been heated so that it is in a sealing 
relationship with heat shrinkable plastic tube 66. That is, tubular 
portion 126 is heated to thereby shrink this portion into an engaging 
relationship with the heat shrinkable plastic tube 66 and to thereby 
activate the adhesive thereon to hermetically bond the interior of the 
tubular portion 126 to the exterior surface of tube 66. 
In this fashion, a reliable, low profile, lightweight, moisture sealed and 
strain relieved electrical connector is formed. 
Although a reliable connection is so formed, electrical conductor 50 can be 
removed from the connector by longitudinally notching the exterior of heat 
shrinkable plastic tube 104 and reheating that tube. This results in a 
slit being formed in the wall of tube 104 which propagates itself until it 
extends from one end of the tube to the other. This reheating also renders 
the heat activated adhesive fluid so as to lubricate the additional 
shrinking of the tube 104. After the slit is complete the tube 104 is 
removed from the insulating layer 98 and the heat shrinkable plastic tube 
66. Since tube 66 had been received in the insulating layer 98, i.e., in 
cavity 118, none of the adhesive on tube 104 has contaminated ferrule 60. 
Thus, electrical conductor 50 can be removed, inspected and replaced or a 
different conductor 50 can be replaced in ferrule 96 via open end 114 and 
a new heat shrinkable plastic tube, similar to tube 104, can be maneuvered 
thereon and heated to rebond the electrical conductor to the insulating 
layer 98. Of course, in order to accomplish this, the new tube should be 
placed either over the electrical conductor or the insulating layer first 
since it is a continuous tube. 
While various embodiments have been chosen to illustrate the invention, it 
will be understood by those skilled in the art that various changes and 
modifications can be made therein without departing from the scope of the 
invention as defined in the appended claims.