Note: Descriptions are shown in the official language in which they were submitted.
ELECTRIC TERlvllNALS IIAVING Pl ATED INTERIOR SURFACFS,
APPARATlJS FOR AND METHOD OF SELECTIVEI Y
PLAT ING SA_D TERMINALS
This application is a divisional of copendiny Canada
Application No. 423,43l~-1 Serial No. 423,L~34 filed on March 11,
1 ~83 .
The present inven-tion relates to selective plating, i . e.,
electroplating selectively only the electrical contact surfaces of
electrical terminals to the exclusion of other surfaces of the
10 terminals and, in particular, -terminals that are attached to a
carrier strip.
In one method of manufacturing electrical temninals, the
terminals are stamped and formed from metal strip and are
attached to a carrier strip. This carrier strip is useful for
15 strip feeding the terminals through successive manufacturing
operations. One necessary manufacturing operation involves
plating, i.e., electroplating the electrical contact surfaces of the
strip fed terminals with a contact metal, usually noble metals or
noble metal alloys. These metals are cha~ acterized by good
20 electrical conductivity and little or no formation of oxides -that
reduce the conductivity. Therefore, these metals, when applied
as plating, wili enhance conductivity of -the terminals. The high
cost of these metals has necessi-tated precision deposition on the
contact surfaces of the terminals, and not on surfaces of the
25 terminals on which plating is unnecessary.
9703-1 CAN -1-
? r3 ;~
Apparatus for plating is called a plating cell and includes
an electr ical anode, an electrical cathode comprised of the strip
fed terminals, and a plating solution, i.e., an electrolyte of
metal ions. A strip feeding means feeds the strip to a strip
5 guide. The strip guide guides the terminals through a plating
zone while the terminais are being plated. The plating solution
is fluidic and is placed in contact with the anode and the
terminals. The apparatus operates by passing elec-trical current
from -the anode through the plating solution to the terrninals.
10 The metal ions deposit as metal plating on those -terminal
surfaces in contact with the plating solution.
There is disclosed in U.S. Patent No. 3,951,761, plating
apparatus in which strip fed terminals are plated by immersion in
a plating solution. The carrier strip is masked, i.e., covered
15 by a conductive strip, that prevents deposition of plating onto
the immersed carrier strip. However, masking requires another
manufacturing operation. Some immersed surfaces are difficult to
mask, particularly the surfaces of small size electrical terminals.
The present invention accomplishes selective plating according to
20 a rapid automatic process and apparatus without a need for
masking immersed terminal surfaces on which plating is
unnecessary. The present invention is particularly adaptecd for
plating only interior surfaces of strip fed, receptacle type,
terminals, and not the external surfaces, despite contac-t of the
25 external surfaces with plating solution.
9703--1 CAN -2-
The apparatus in accordance with the invention is
characterised in that the strip guide is a mandrel that is
continuously rotated as the strip of electrical terminals are
oontinuously fed to the mandrel partially wrapped against the
S mandrel, and fed from the mandrel. The mandrei has a plurality
of nozzles located around the mandrel's axis of rota-tion. The
anode has a plurality of anode extensions which are mounted
within the nozzles. The anode extensions are movable into and
out of the interiors of the terminals that are against the
10 mandrel. A conduit is provided which carries plating solution
under pressure through the nozzles and upon the anode
extensions. The nozzles inject plating solution into the interiors
of the terminals in which the anode extensions have been
received. A source of electrical potential supplies electrical
15 current which flows frorrl the anode extensions through the
piating solution to the cathode, and plating the interior surfaces
of the terminals.
A better understandincJ o-F the invention is obtained by
way of example from the following description and the
~o accompanying drawings, wherein:
FIGU~E 1 is a perspective view of apparatus for continuous
plating accordincl to the invention with parts of the apparatus
exploded .
FIC;URE ~ is a perspective view of the apparatus shown in
~5 Figure 1 with parts assembled.
9703-1 CAN -3-
F::lGlJRE 2A is a schematic view of the apparat~ls shown in
Figure 2 combined with a bel-t mechanism.
FIGURE 3 is an enlarged fragmentary perspective view of a
por tion of the apparatus shown in Figure 2 .
FIGURE 4 is a view in section of a plating cell apparatus
incorporating the apparatus of Figure 2.
FIC,URE 5 is a fragrnentary plan view, taken along the line
5-5 of Figure 4, of a portion of the apparatus shown in Figure
4, and illustrating an advanced anocde extension.
FIGURE 6 is a view similar to Figure 5, illustrating a
retracted anode extension
FIGURE 7 is a perspective view of a shaft of the apparatus
shown in Figure 2.
FIGURE 8 is a section view of the shaft shown in Figure 7.
FIGURE 9 is a perspective view of a vacuum aspirator of
the apparatus shown in Figure 2.
FIGURE 10 is an elevation view of an anode extension of the
apparatus shown in Figure 2.
FIGURE 11 is an elevation view in section of a portion of an
20 electrical receptacle -that has been immersion plated.
FIGURE 12 is an eievation view in section of an electrical
receptacle that has been plated according to the present
invention .
FIGURE 13 is an exploded view of an alternative embodiment
25 of this invention.
9703-1 CAN -L~-
5'~
FIGURE 14 is an enlarged fragmentary perspective view of a
portion of an alternative embodiment of the apparatus shown in
Figure 2.
FIGURE 1llA is a plan view of a terminal having a contact
5 slot receptacle showing -the side of the terminal that faces the
mandrel .
FIGURE 15 is a view in section of a plating cell apparatus
incorporating the alternative embodiment of Figure 13 in the
apparatus of Figure 2.
FlGUFcE 16 is a fragmentary plan view taken along the line
16~16 of Figure 15, and illustrating an anode extension-spreader
aligned to enter the terminal.
FIGURE 17 is a view similar to Figure 16, illustrating an
advanced anode extension-spreader.
FIGURE 18 is a perspective view of the shaft of -the
apparatus shown in Figure 15, illustrating the asymmetric cam
used to advance and retract the anode extension-spreaders.
FIGURE 19 is a section view of the shaft shown in Figure
18.
FIGURE 20 is an enlarged fragmentary perspective view of
the alternative embodiment of Figure 13 illustrating the operation
of the asymmetrical cam.
FIGURE 21 is an enlarged fragmentary view of an elec-trical
terminal that has been plated according to the alternative
25 embodiment of the present invention.
9703-1 CAN -5-
Figures l, 2, and 4 illustrate a mandrel apparatus l
according to one embodiment of the invention comprising an
assembly of an insulative disc flange 2, an insulative
wheel-shaped mandrel 3, an insulative noz~le plate 4, a
5 conductive titanium anode p!ate 5, a conductive copper-graphite
bushing 6 that is attached to the anode plate 5, an insulative
anode extension holder plate 7, an insulative hydraulic
distributor plate 8, a shaft 9, an end cap 10 for fitting on the
end of the shaft 9, a washer 11 and a sealing ring 12
10 compressed between the disc flange 2 and the end cap l O. The
insulative parts 2, 3, 4, 7, and 3 are advantageously rnachined
from a high density polyvinylchloride, and are stacked together
with -the conductive parts S and 6. E3olts 13 are assembled
through aligned bolt receiving holes 14 through each of the
15 parts 2, 3, 4, 5, 7, and 8. These parts are mounted for
rotation on the shaft 9. A continuous length of strip fed
electrical terminals 15 are integral with, and serially spaced
along, a carrier strip 16. The terminals 15 are shown as
electrical receptacles oF barrel forms or sleeve forms. These
20 forms are exemplary only, since many forms of electrical
receptacles exist. The strip fed terminals 15 are shown in
Figure 2A as being looped over two idler pulleys 17 and onto a
cylindrical alignment surface 18 of the mandrel 3.
Figure 3 shows a series of radially projecting teeth 19
25 integral with and projecting from the alignment surface 18. The
terminals 15 are nested in the spaces that form nests 20 between
9703-1 CAN -6-
the teeth 19. The carrier strip 16 has pilot holes 21 in which
are registered knobs 22 projecting frorn the mandrel 3. The
flange 2 provicles a rim projecting against and along the carrier
strip 16. Figure 2A illustrates a belt looped over the pulleys 17
5 and also over two additional pulleys 25. The belt 24 also is held
by the pulleys 25 against the terminals 15 that are nestecl in -the
nests 2Q, and the belt re-tains these terminals 15 against the
alignment surface 18 of the mandrel 3. Thereby the stripped
terminals 15 are between the belt 24 and the alignment surface
10 18, whereas the belt 211 is between the strip fed terminals and
the pulleys 17.
Figure 3 shows a nozzle wheel 4 that is turreted with a
plurality of radially spaced orifices or nozzles 26. Figures 1 and
4 show -that the nozzles 26 are aligned with and open into the
15 nests 20. Anode extensions 29 are mounted within the nozzles
26. These figures also show the anode plate 5 tha-t includes a
plurality of radially spaced anode extension receiving openings
27 -that are aligned with and open into the nozzle openings 26.
The anode extension holder plate 7 includes a plurality of anode
20 extension receiving chambers 28 aligned with and comn unicating
with the openings 27 in the anode plate 5.
Figure 10 shows an anode extension 29 machined from a
conductive metal such as titanium. The anode extension has an
enlarged diameter body 30 and a reduced diameter elongated
25 probe 31 in-teqral with the body 30. A section of the probe 31
is fabr icated of a coil spring 31 A which makes a probe flexible.
9703-1 CAN -7-
A radially projecting insulative collar 32 is mounted on the tip of
-the probe 31. One or more flat passageways 33 are recessed in
the periphery of the body 30 and extend longit~dinally from one
end of the body to the other.
As shown in ~igures 4, 5, and 6, an anode extension body
30 is mounted for reciprocation in each chamber 28. The probe
31 of eacl- anode ex tension body 30 projects into the openings
27, 26 that are aligned with the respective chamber 28. The
aliyned openings 27, 26, together with the chambers 28,
10 cooperate to form anode extension passageways that mount -the
anode extensions 29 for reciprocation. The probe 31 of each
anode extension 29 is mounted for advance into an interior of a
terminal 15, as shown in Figure 5, and also for retraction out of
an interior of a terminal 15, as shown in Figure ~. As each
15 anode extension 29 is advanced into an interior of a terrninal 15,
the body 30 of the anode extension will impinge and stop against
the anode plate 5, providing an electrical connection
therebetween .
Figures 1 and 4 show that the distributor plate 8 includes a
20 central opening 34 communicating with a plurality of electrolyte
passageways 35 that extend radially outward of the opening 31
and communicate with respective anode extension chambers 28.
Figures 7 and 8 show the shaft 9 that is made of conductive
stainless steel. The shaft 9 is provided with a central stepped
2~ cylindrical electrolyte conduit 36 extending entirely the length of
the sha-Ft. A plurality of electrolyte ports 37 connect the
9703-1 CAN -8-
5~
conduit 36 wi-th a channel-shaped electrolyte inlet manifold 38
recessed in the cylindrical periphery of the shaft. A plurality
of vacuum ports 39 connect the conduit with a channel-shaped
vacu~Jm manifold 40 -that is recessed in the cyiindrical periphery
of the shaft 9 so that the central opening 34 of the plate 3
communicates with the manifolds 38 40. The electrolyte
passageways 35 that extend to the central opening 34 will
communicate with the electrolyte inlet manifold 38, and then the
vacuum manifold 40 in turn as the distributor plate 8 is
rotated relative to the shaft 9.
Figure 9 taken with Figures 4 and 8 show a vacuum
aspirator 41 machined From polyvinylchloride. The aspirator 41
is seated in the conduit 36 of the shaft 9. One or more
lonyitudinal electrolyte passageways 42 are recessed in the
periphery of the aspirator 41 and permit electrolyte flow along
the conduit 36 into the ports 35 and the electrolyte inlet manifold
38. A longitudinal bore 43 through the aspirator 41 permits
additional electrolyte flow through the aspirator 41 to the end
of the conduit 36 through a passageway 44 through the end cap
10 and out a conduit 45 that is attached to the end cap 10 and
communicates wi-th the cap passageway 44. A series of vacuum
ports 46 -through the aspirator intercept the bore 43. The
vacuum ports 46 communicate with the vacuum ports 39 and with
the vacuum manifold 40. The electrolyte flow along the bore
produces a vacuum in the vacuum ports 46 and also in the
9703-1 CAN -9-
S;3
vacuum manifold 40. This phenomenon i5 well known in the art
of hydraulic fluid devices.
Figure 4 shows schematically a plating cell, including a
sollrce E of elec-trical potential applied across the strip l fi and
5 the anode plate 5, a tank 47 containing a plating electrolyte 48
of precious or semi-precious metal ions and a supply hose 49
leading from the tank 47 through a pump 50 and into the conduit
36 Or silaft 9. ~ drive sprocket with an axle bushing is secured
on the distributor plate 8.
In operation, the sprocket is driven by a chain drive (not
shown) to rotate the mandrel apparatus 1 and to feed the strip
fed terminals 15 upon the mandrel 3. Electrolyte 48 is supplied
under pressure From the hose 49 into the conduit 36 oF the shaft
9. An electrical potential from the source E is applied between
15 the anode plate 5 and the strip fed terminals 15 to produce a
current 1. The terminals 15 serve as a cathode onto which
precious or semi-precious metal ions of the electrolyte 48 are to
be plated. Upon rota-tion of the mandrel 3, each of the anode
extension chambers 28, in turn, will communicate wi-th the
20 electrolyte manifold 38. The electrolyte will flow under pressure
into the eiectrolyte manifold 38, and from there into several of
the anode extension chambers 28 that communicate with the
electrolyte manifold 38. The anode extensions 29 in these anode
extension chambers 28 will be advanced to positions as shown in
25 Figure 5 by the e!ectrolyte under pressure. Electrolyte will flow
past the anode extension bodies 30 along the anode extension
9703-1CAN -10-
passa~eways 33, and be injected by the nozzles 26 into the
interiors of the lerminals 15, wetting the terminal interiors and
the anode extension probes 31 which are in the terminal
interiors. Sufficient ion density and current density are present
5 for the ions to deposit as plating upon the surfaces of the
terminal interiors. The proximity of the probes 31 to the
terminal interiors assures that the surfaces of the terminal
interiors are plated, to -the exclusion of the other terminal
surfaces. The collars 32 on the anode extensions are sized
1û nearly to -the diameters of the interiors of the terminals to
position the arlode extension probe precisely along the central
axis of the terminal interiors during the plating operation.
As the mandrel apparatus 1 is further rotated, the anode
ex-tension chambers 28 will become disconnected from the
15 electrolyte manifold 38, and will become corlnec-tecl with the
vacuum manifold 40. The vacuum present in the vacuum
manifold 40 will tend to draw out residual electro!yte in the
several anode extension chambers 28 that communicate with the
vacuum manifold 40. The vacuum also will retract the anode
20 extensions 29 from their acdvanced positions, as shown in Figure
5, to their retracted positions, shown in Figure 6. Thereby the
probes 31 become withdrawn from the interiors of the terminals
15, plating deposition will cease, and the terminals become
removed from the mandrel apparatus 1 as the strip 6 continues
25 to be advanced.
9703-1 CAN -11-
Figures 13 and 15 illustrate a manclrel apparatus 1 '
according to an alternative embodiment of the inverl-tion
comprising an assemt~ly of an insulative bearing case 5LI, a
two-piece insulative disc flange 2', an insulative wheel-shaped
5 mandrel 3', an anode extension-spreader retaining ring 56, and a
conductive shaft 9'. Bolts 13' are assernbled through aligned
bolt receiving holes 14' through each of -the parts 54, 2', and 3'.
These parts are mounted for ro~ation on the shaft 9'. A
continuous length of strip fed electrical terminals 15' are integral
10 with, and serially spaced along, a carrier strip 16'. The strip
fed terminals 15' are strip fed to the apparatus 1 ' in the same
manner as are the strip fed terminals 5 as sho~vn in Figure 2A.
This embodiment of the invention is used with electrical
terminals having contact slot receptacles of the type shown in
15 Figure 14A. In order to plate inside a slotted terminal,
according to the invention, the slot first must be spread apart
to permit insertion of the anode extension. As is illustrated in
Figures 13 and 14, anode extension-spreaders 29' are used in
this embodiment. The anode exter-sion-spreaders 29' are
20 inserted essentially at right angles to the terminals 15'. Figure
14 shows that each anode extension-spreader 29' is comprisecl of
a conductive metal strip 60 and a plastic spreader body 62. The
metal strip 60 extends below the plastic spreader. The plastic
spreader body 62 has a retaining slot 64 along its upper edge
25 which cooperates with the anode extension-spreader retaining
ring 56. The anode extension-spreader is shaped at its
9703-1 CAN -1?-
5~
outermost encl 66 to spread and fit within the terminals 15' and
to properly position the metal anode portion inside the -terminal.
Figure 14 shows that mandrel 3' is turreted with a plurality
of radially spaced anode extension-spreader passageways 58
5 which extencl outwardly to the alignment surface 18' and form a
series of nests 20' along the periphery mandrel 3'. The
-terminals 15' are held in these nests and against the mandrel as
the -terminals are plated internally.
Figure 14 further shows that mandrel 3' is turreted with a
plurality of radially spaced orifices or noz~les 26' at the base of
the anode extension-spreader passageways 58. When the anode
extension-spreaders 29' are placed in the mandrel the metal
strips 60 lie within the nozzles 26'.
As shown in Figures 14 15 16 and 17 the anode
15 extension-spreader 29' is mounted for reciprocation in each
passageway 58. The shaped end 66 of each anode
extension-spreader is mounted for advancing into the slot of a
terrninal 15' as shown in Figure 16. Figure 17 shows the
advanced anode extension-spreader in the terminal 15'. As each
20 anode extension-spreader 29' is advanced it is held in contact
with the conductive shaft 9' providing an electrical connection
therebetween .
Figures 15 18 and 19 show the conductive shaft 9' is
provided with a central cylindrical electrolyte conduit 36'
25 extending along part of the length of the shaft. A
channel-shaped electrolyte outlet 68 is recessed in the cylindrical
9703-1 CAN -13-
t r~
periphery of the shaft 9'. As the mandrel 3' revolves about
shaft 9~, the nozzles Z6' comrnurlicate with the electrolyte outlet
68 thus providing access of the electrolyte solution to the
terminal 15'.
Figures 15, 18 and 19 show the asymmetric cam 70 on the
shaft 9'. The shape of cam 70 can be seen in Fiyure 20.
Mandrel 3' has a circular opening 72 a-t its center which is
dimensioned to closely fit and cooperate with shaft 9'. The cam
70 fits into a circular opening 72 on the side of mandrel 3'
having the anode extension-spreader passageways 58.
Approximately half of carn 70 fits snugly against passageways 58
while the other part of cam 70 is spaced apart from passageways
58. The inner ends 74 of anode extension-spreaders 29' are
held snugly against cam 70 by the anode extension-spreader
retaining ring 56.
As mandrel 3' rotates around shaft 9', the anode
extension-spreaders 29' are first extended into the terminals 15'
as cam 70 moves against passageways 58 and then retracted from
terminals 15' where the cam is spaced apart from said
passageways.
Figure 15 shows schematically the mandrel apparatus,
including a source E of electrical potential applied across the
strip 16 and the conductive shaft 9'. A drive sprocket with an
axle bushing is secured to the mandrel 3'.
in operation, the sprocket is driven by a chain drive (not
shown) to rotate the mandrel apparatus 1' and to feed the strip
9703-1 CAN -14-
fed terminals 15' upon -the mar-drel 3'. Electroly-te 1~8l i5
supplied under pressure ~rorn a plating bath (not shownj into
~he conduit 36' of the shaft 9'. An electrical potential from the
source E is applied between the shaft 9' and the strip fed
5 terminals 15' to produce a current I. The terminals 15' serve as
a cathode onto which precious or semi-precious metal ions of the
electrolyte 48' are to be plated. Upon rotation of the mandrel
3', each of the nozzles 26', in turn, will communicate with the
electrolyte outle-t 68. The electrolyte will flow under pressure
10 into the electrolyte outlet 68, and from there into several of the
nozzles 26' that comrnunicate with the electrolyte outlet 68. The
anode extensions 29' in these anode extension-spreader
passa~eways 58 will be advanced to positions as shown in Figure
17 by action oF the asymmetric cam 70. Electrolyte will flow past
15 the metal portion anode extension-spreader 29' into the in-teriors
of the terminals 15', wettin~ the terminal in-teriors and the
portion of the anode extensions which are in the terminal
interiors. Sufficient ion density and current density are present
for the ior-s to deposit as plating upon the surfaces of the
20 terrninal interiors. The proximi-ty of the anode
extension-spreader end 66 to the terminal interiors assures that
the surfaces of the terminal interiors are plated to the exclusion
of the other terminal surfaces. Excess electrolyte will flow past
the anode extension-spreader and will he re-turned -to the plating
25 bath (not shown).
9703-1 CAN _15_
As the mandrel apparatus 1' is further rotated, the
passacJeways 58 will become disconnec-ted from the electrolyte
outlet 68. The action of cam 70 will cause the anode
ex-tension-spreaders to withdraw From the interiors of the
terminals 15', and plating deposition will cease. The -terminals
become removed from the mandrel apparatus 1 ' as the strip 16'
continues -to advance.
In this alternative embodiment 1 ' of the mandrel apparatus,
the use of mechanical means to reciprocally move the anode
10 extension-spreaders into and out of the terminals eliminates a
number of parts that are necessary For the hydraulically
operated mechanism to provide reciprocating movement.
Mechanical means can also be used with mandrel apparatus 1.
The use of anode extension-spreaders inserted at right angles to
15 the terminals instead of a straight line insertion also reduces the
number of par-ts required ~or the mandrel apparatus.
Because the slots in the terminals used in embodiment 1 '
rnust be spread apart to permit insertion of the anode extension,
the anode extension-spreaders do become worn after a period of
20 time, Depending upon the type of plastic used, over 25,000
insertions per anode extension-spreader can be made be-Fore
replacement is necessary. The worn anode extension-spreaders
are designed to be disposable and are easily replaced by
removing bolts 13 and separating the three main pieces. The
25 anode extension-spreader retaining ring is then removed and new
anode extension-spreaders inserted. ~:iange 2' is made in two
9703-1 CAN -16-
5;~
parts to facilitate replacement of the anode extension-spreader
retaininq ring.
The present invention relates additionally to an elec-trical
terminal that has an interior with a contact metal deposit applied
5 by the apparatus described in conjunction with Figures 1
through 10 or Figures 13 through 20. The deposit has
observable characteristics that distin~uish from characteristics of
plating applied by apparatus and a process other than that
described in con junction with Figures 1 through 10 or Figures 13
10 through 20. A standard requirement of the electrical industry is
that an electrical receptacle of base metal, copper or its alloy,
should be plated first with nickel or its alloy, then have its
interior plated with a precious or semi-precious metal such as
cobalt-gold alloy that assures electrical conductivity. Further,
15 the plating must equal or exceed a specified thickness that
allows for wear removal of the layer by abrasion. For example,
one standard specification recluires 0. 38 microns thickness of
cobalt-gold plating extending from the end of the receptacle to a
depth of 0.51 centimeters within the receptacle interior. The
20 exterior surfaces of the receptacle are not subject to wear
removal . Therefore, only a flash, i . e., 0.13 microns in
thickness, of platincJ is required.
The deposit of noble metal or noble metal alloy may also be
comprised of successive layers of noble metals such as gold,
25 palladium, platinum, silver, or their alloys. Successive layers of
different noble metals may also be plated on one another, such
9703-l CAN -17-
5;~
as an under-layer of palladium followed by an over-layer of
gold .
Heretofore, plating of electrical receptacles was
accompl ished by the prior processes of plating over a strip of
5 base me-tal prior to forming the strip into receptacle
configurations, or by immersing fully formed electrical
receptacles in plating electrolyte and plating all the surfaces of
the receptacles. Each of these prior processes had
d isadvantages .
Forming a base metal strip subsequent to plating applies
bending stresses in the plating. Observation by a m7croscope
would reveal s-tress cracks in the surface of the outer plating
layer. The cracks would be most prevalent in the areas of most
severe bending. Severe bending also would cause localized
15 separations of the outer plating layer from the metal underlying
the outer plating layer. These separations, called occlusions,
would be observed by microscopic observation of a cross-section
of the outer plating layer and the underlying metal. These
stress cracks and occlusions are defects that would permit
20 corrosion of the underlying base metal and would be adverse to
quality of -the outer plating layer. Further, stamping of the
plated base metal produces shears through the plating layers,
exposing the base metal underlying the piating.
Figure 11 depicts a cross-section of an electrical receptacle
25 plated with a layer of nickel 51, and then immersion plated in
cobalt-gold electrolyte, using an anode external to the receptacle
9703-1 CAN -1~3_
S~
during plating. Both the interior and the exterior of the
receptacle receive piating deposit S2. The deposit on the
interior rapid!y tapers in thickness from the end of the
receptacle toward the innermost depth of the receptacle. ~or
5 example, the thickness varies -from 0. 51 microns at the end of
the receptacle to ~ero thickness at a depth of 0. 36 centimeters
from the end of the receptacle. This tapered characteristic
results from the progressive exponential decrease in cl-arge
density or current density due to distance from the external
o anode. So that thinner portions of the tapered deposit will meet
the requirement for minimum thickness, other portions of the
deposit must have excess thickness that wastefully consumes the
plating ions of the electrolyte. Since the exterior of the
receptacle is relatively near the external anode, the deposit is
15 thicker than the deposit on the receptacle interior. For
exampie, the deposit has a -thickness of l.1 microns at a depth
of 0.05 centimeters and a thickness of 0.51 microns at a depth of
0. 36 centimeters . Deposit on the exterior of the receptacle is
not subjected to wear removal. There-fore, any plating in excess
20 of a flash, i.e., approximately 0.13 micr~ns in thickness, is
wasted consumption. Masking, i.e., covering, -the receptacle
exterior during ,s lating will eliminate the exterior deposit.
~lowever, masking requires an operation prior to plating and is
not conducive to a mass production process. Further, masking
25 does not eliminate wasteful consumption of a tapered deposit on
the interior of the receptacle. Upon removal oF the masking, an
9703 -1 CAN -19-
abrupt, nnt tapered, edge of the platincJ would be observed
where the plating had met the rnasking.
In the receptacle 15 of the presen-t invention, shown in
Figure 12, the terminal is stamped and formed from a base metal
5 of copper or its alloy. A layer of nickel or its alloy is plated
over all surfaces of -the terminal, includin~3 -the shearecl edges
produced during the stamping and forming operations. lJsing
the apparatus as described in conjunction with Figures I ~hrough
10, the interior is plated with an outer layer 76 of a precious or
10 semi--precious metal such as gold, platinum, palladium or silver,
or the alloys thereof, such as cobalt-gold. For example, an
outer layer of plating in the form of cobalt-gold of relatively
even thickness is deposi ted aiong the length extending from the
end of the receptacle to a distance of 0. 51 centimeters toward
15 the innermost depth of the interior. An abrupt and s-teep -taper
is at the edges of the piating. There is an absence of
cobalt-gold, of equal or greater thickness, on the receptacle
exterior. The even thickness and abrup-t tapered edges are
characteristics of the plating deposit achieved by selective
20 plating according to -the invention. The !ength of the plating
deposit substantially is equal to the length of the anode
extension probe 31 that extends within the receptacle interior.
At the terminal end of the probe 31, the charge and current
densities abruptly cease, causing an abrupt tapered edge of the
25 plating deposit. The charge and current densities also cease at
the chalTlfered end of the receptacle, causing an abrupt tapered
9703-1 CAN -20-
5~
edcJe of the plating deposit. There is no need for masking the
receptacle exterior, and the plating deposit does not have -the
non-tapered edge that would result from mashing. Further, the
plating deposi t is substantially free of stress cracks and
5 occiusions, and has a grain strllcture characteristic of plating
deposit .
Figure 21 shows a receptacle 15' plated, using the
apparatus as described in conjunction with Figures 13 through
20. The plating deposit 76' on the interior surface of 15' has
10 the same characteristics as the plating 76 on terminal 15 as
shown in Figure 12.
The invention has been described by way of examples only.
Other forms of the invention are to be covered by -the spirit and
scope of the claims. The receptacles 15 and 15' are only
15 exemplary of the many forms of electrical recept3cles, the
internal surfaces of which are capable of being plated by the
apparatus of the invention.
9703-1 CAN -21-
