Apparatus for plating

An apparatus optimum for partially plating such rectangular objects as an IC lead frame obtained by subjecting thin metal pieces to press working and etching. The apparatus is characterized in that a support carriage aligns and supports the plurality of objects to be plated in advance, positioning means align the objects as regards the plating tank the lead wire as a cathode is contacted at the same time with the upper side of each object to be plated and the whole of the plural number of objects to be plated is masked, thereby performing plating by jetting the plating liquid onto respective portions to be plated.

BACKGROUND OF THE INVENTION 
The present invention concerns an apparatus for partially plating a portion 
of a rectangular object by jetting the plating liquid. 
Although there are many apparatuses proposed and practiced for partial 
plating, particularly those for efficiently conducting partial plating of 
such objects as an IC lead frame comprising a thin metal piece of a 
predetermined size, apparatus for handling several objects such as an IC 
lead frame comprising a thin metal piece of a rectangular shape subjected 
to press working and etching to obtain a predetermined, comparatively 
small size is not available in the art as far as the inventors of this 
invention are aware. The reason for this is that it is difficult to 
process such a plural number of rectangular objects simultaneously, and it 
is difficult to improve the processing efficiency of such an apparatus 
compared to other apparatuses used for other methods of processing, for 
instance partially processing a long piece of coiled material by rewinding 
such a coil and partially plating the portion intended for plating while 
it is being transferred, and cutting the thus plated object into 
predetermined sizes and shapes. 
SUMMARY OF THE INVENTION 
When plating a rectangular object as mentioned above, such as an IC lead 
frame obtained by press working and etching a thin metal piece, it is 
usually necessary to plate the portion to be plated with gold or other 
precious metal. It is much more efficient to process a plural number (for 
instance 10 to 20) of sheets in one batch rather than individually. 
For this purpose, it is desirable to align and support a plural number of 
objects on the carriage in advance, and to determine the descended 
position of the objects to be plated as regards the plating tanks and to 
contact the lead wire which is used as a cathode over the upper side of 
the objects to be plated in such a way as to use it as a mask, thereby 
facilitating an easy and sure plating processing of a plural number of 
objects such as partial silver plating. 
It is an object of the present invention to provide an apparatus useful for 
conducting the plating as above mentioned. The present invention is now 
explained in detail reference being made to the appended drawings. The 
above and other objects and features of the present invention will be 
understood in further detail when viewed in the light of the attached 
drawing wherein FIGS. 1 to 15 illustrate embodiments thereof and the 
following description.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In referring to the structure of the present invention, the reference 
number 1 (FIG. 1) denotes a plating apparatus comprising mainly a plating 
tank 2, a support carriage 3 (FIG. 2) and a pressure means 4. An apparatus 
commonly known as "Sparger" is used for the plating tank 2. More 
concretely, the apparatus has a first mask 6 provided with jet apertures 5 
as shown in FIG. 6, a nozzle 7 which also acts as an anode, and a 
projection pin 8 on the upper surface to be used as a positioning means as 
described hereinafter. The first mask 6 is provided with a plural number 
of the jet apertures 5, the number of which corresponds to the number of 
the portions to be plated on the objects 19 to which reference will be 
made later. 
The support carriage 3 (FIG. 7) mainly comprises a carrier base 11 movable 
along over a pair of rails 10 which extends above the plating tank 2 and a 
rack base 12 suspended from said carrier base 11. As is evident from the 
details shown in FIG. 7, a standing bar 13 positioned on the carrier base 
11 is provided with a spring 14 and a mobile bush 15 at the top thereof, 
and said rack base 12 is suspended from the carrier base 11 in a fashion 
to allow free descent and return to the original position via fixed plate 
16 fixed to said mobile bush 15 and a suspension bar 17. The reference 
numeral 18 denotes a holder for the objects to be plated to receive both 
ends of said objects 19, while 20 denotes a guide provided with aperture 
21 to act as a positioning means. 
The object to be plated 19 in this instance is an IC lead frame A 
comprising a thin metal piece subjected to press working and etching as 
shown in FIG. 9. Such IC lead frame usually requires plating using 
precious metal to be performed at the portion B. 
In the apparatus in accordance with the present invention the carriage 3 
for supporting objects to be plated plays an extremely significant role, 
and therefore a detailed description of said carriage is given herein 
below reference being made to FIG. 7 as well as to FIG. 8. 
As mentioned before, it is much more efficient to process a plural number 
(for instance 10 to 20) of sheets in one batch rather than individually. 
Therefore, it is necessary to align a plural number of objects 
horizontally in advance, and as the plating operation is conducted over a 
line comprising various pre-treatments (such as washing with water, 
degreasing, activation, strike plating, etc.), the plating process proper, 
and post-treatment (washing with water, washing with hot water, drying, 
etc.), it is also necessary to transfer the objects which are aligned and 
supported horizontally and also to facilitate change of the position of 
the objects vertically up to the height of the surfaces at various steps. 
The carriage 3 shown in FIGS. 7 and 8 can comply with such a need. More 
concretely, the support carriage 3 comprises a carrier base 11 and a rack 
base 12 wherein the rack base 12 is supported in a suspended position, and 
a plurality of holders 18 are fixed to the rack base 12 in such a way that 
their positioning is freely adjustable. By installing the positioning 
means 20 (FIG. 7) on the rack base 12, its applicability is improved 
greatly and the carriage 3 may be used throughout the entire steps of the 
plating line with a greater ease in use and manufacture, thereby improving 
the design freedom of the apparatus for the whole plating line. Such a 
carriage is shown in FIGS. 7 and 8. 
As mentioned above, the carrier base 11 is provided movably on a pair of 
rails 10 (FIG. 7), has sliders 40 to engage respectively with the rails 10 
on the lower surface of the frame shaped carrier base 11, and is further 
provided with standing bars 13 on the upper surface thereof. The reference 
numeral 14 denotes a spring provided outside the standing bar 13, the 
lower end of which abuts against the upper surface of the carrier base 11, 
and the upper end abuts against the mobile bush 15 encircling the upper 
portion of the standing bar 13. The mobile bush 15 is prevented from 
becoming loose from the standing bar 13 by the stopper ring 41 (FIG. 8). 
The rack base 12 is suspended from the carrier base 11 as above described 
and becomes lowered following the pressure applied from another source, 
and it elevates and returns automatically when the pressure is removed. In 
other words, the rack base 12 shaped like a frame has opposing sides 12a 
connected to said mobile bush 15 via the bush plates 16, 16a and the 
suspension bar 17. The rack base 12 is suspended between two carrier bases 
11 and below said carrier bases 11 so that the length of the suspension 
bar 17 is longer by the distance l than the standing bar 13. The rack base 
12 has cross bars [three in the drawing] 12b upon which are to be fixed 
holders 18 for objects to be plated. Each holder 18 comprises sectioned 
pieces instead of one long piece, and a plurality of these sections are to 
be fixed to the cross bars 12b. They are provided with concave portions of 
a size and shape adapted to receive the end portions of the objects 19. In 
the embodiment illustrated, there is shown a holder which is to be 
attached by placing the same on the center cross bar upon which are formed 
concave portions on the opposing two sides. On the other hand, the holder 
to be attached to the two cross bars on both sides of the center cross bar 
has a concave portion only on one of the opposing sides. These holders 18 
are to be fixed upon the cross bars 12b by screws 42 individually, and the 
fine adjustment for their positions may be made by giving the hole 43 for 
screws, a size somewhat bigger than that of the screw 42. [See FIG. 8]. 
This fine adjustment is suitably conducted depending on such conditions as 
the degree of parallelism of the holders 18, the degree of opposing 
distance, etc. the position of the opening 5 in the first mask 6 of the 
plating tank 2 mentioned hereinbefore, and other conditions. For this 
reason there is provided a clearance between the holders 18 and 18, and 
other holders also are attached with such a clearance therebetween. 
The reference numeral 20 is a guide for "positioning means for descent" 
provided on the rack base 12. In other words, there is formed a through 
hole 44 on the cross bar 12b of the rack base 12 through which is inserted 
and fixed a guide 20, the opening 21 thereof being adapted to engage with 
a pin 8 extendingly provided on the upper surface of the plating tank 2 
mentioned above. [See FIG. 6]. 
The pressure means 4 comprises mainly of a pressure member 22 and its case 
23 (FIG. 5). The pressure member 22 is attached to the lower end of the 
rod 24a of the pressure cylinder 24 (FIG. 1), and is provided with the 
second mask 25 which freely contacts the upper surface of the objects 19 
(FIG. 6). The reference numeral 26 denotes the guide bar. The second mask 
25 is preferably made of a material having soft elasticity. The case 23 
encircles the side surface of the pressure member 22 and is engaged with a 
pressure member 22 by a screw 28 which goes through the orifice 27. 
Accordingly, the case is movable in respect of the pressure member 22 in a 
vertical direction by the length of the orifice 27. Between two sides of 
the case 23 is extended a lead wire 29 in the shape of a belt which 
functions as a cathode below said second mask 25. The position of the lead 
wire 29 at which it is attached to the case 23 is movable and is such that 
the lead wire may be attached at an optimum position on the upper surface 
of the objects 19 to be plated in respect of the case 23. The reference 
numeral 30 denotes a screw to attach the lead wire 29. On the outer side 
of the case 23 is provided a means to position the means 8 with respect to 
the plating tank 2, which in the embodiment shown is a bush 32 provided 
with an opening 31. 
The operation of the apparatus is now explained. In the state where the 
support carriage 3 is positioned above the plating tank 2, the pressure 
cylinder 24 positioned further above is activated. The pressure member 22 
attached to the lower end of the rod 24a descends and the case 23 is 
lowered because it is suspended from the pressure member 22. The support 
carriage 3 then is lowered, or more concretely the pressure member 22 
abuts the rack base 12 and presses it down. At this time, the lead wire 29 
contacts the upper surface of the object 19, and if the object 19 is 
unsuitably supported by the holders 18 for the objects to be plated, then 
the position of the object 19 is corrected to be suitable in respect of 
the holder 18. 
At the lowest position of movement, the projecting pin 8 becomes engaged 
with the means for positioning 20 and 32 as shown in FIG. 6, thereby 
positioning the objects to be plated 19 to be in suitable positions in 
respect of the jet holes 5 of the first mask 6. With the upper surface of 
the plurality of the objects 19, the lead wire 29 contacts and the second 
mask 25 abuts the non-contacting portions of the lead wire 29 with its 
soft elasticity acting properly. In this state, the plating liquid is 
jetted from the nozzle 7 which also acts as an anode and performs partial 
plating on the lower surface of the object 19 which is exposed through the 
jet hole 5, for instance silver plating. 
Upon completion of the plating process, the pressure cylinder 24 acts to 
raise the pressure member 22. The bottom of the second mask 25 first 
detaches itself from the upper surface of the object to be plated 19, and 
then the lead wire becomes detached therefrom. Accordingly, the object 19 
moves attached to the second mask 25 and does not become free from the 
holder 18. As these pressure means 4 are raised, the rack base 12 returns 
to its original position or ascends, and is sent to the next plating step, 
for instance silver peeling, over the rail 10. At this time, another 
support carriage which has gone through the pre-treatment, for instance 
washing with water, is transferred to a position directly above the 
plating tank 2 to repeat the above mentioned operation. 
The modified example of the support carriage 3 is now explained reference 
being made to FIGS. 10 to 15 wherein only the rack base and its 
accessories are shown while the carrier base and others are not shown. 
The carriage, or more concretely its rack base generally, comprises a fixed 
holder and a mobile holder to support the objects to be plated, and there 
is provided a continuous step portion in the longitudinal direction on the 
fixed holder, while there is provided a concave portion with a step on the 
mobile holder to improve the multi-use of the rack base in supporting 
objects with different widths and lengths. 
The structure of the carriage is now explained; the reference numeral 50 
denotes a rack base shaped like a frame comprising a pair of opposing 
sides 51a, 51b and three cross bars 52a, 52b and 52c. One of the cross 
bars, the bar at the center 52b in the embodiment shown, is provided with 
a fixed holder 53, while the other cross bars, those on both sides, 52a 
and 52c, in the embodiment shown are provided with plurality of mobile 
holders 54. 
The fixed holder 53 may be constructed by joining a plural number of 
sections over the cross bar 52b, or alternately one long piece may be 
placed over the cross bar 52b. If one long piece of fixed holder 53 is to 
be used, the cross bar 52b itself may be formed as a fixed holder 53 
instead of placing it on the cross bar 52b. On the fixed holder 53 is 
formed a support step 55 continuing in the longitudinal direction on the 
opposing side 56 (FIG. 13). 57 denotes a sloping guide for facilitating 
the setting of the object 19 to be plated. 
The plural number of mobile holders 54 are identically shaped and 
structured, and the following description is given in respect of one 
mobile holder 54. The mobile holder 54 (FIG. 11) is provided movably in 
respect of its position in the longitudinal direction of the objects 19 
over the cross bars 52a and 52c. For facilitating the change of positions, 
the mobile holder 54 has an orifice 58 through which are inserted two 
stopper screws 59 screwed to the lower ends of the cross bars 52a and 52c. 
When these screws 59 are removed, the mobile holder 54 may be freely 
replaced with other type. 
The mobile holder 54 further forms a concave portion 62 provided with a 
support step 61 on the opposing sides 60. It is possible to shape the 
concave portion 62 like a bow instead of a triangle as shown in the 
drawing. The reference numeral 63 is for a sloping guide for facilitating 
setting of the objects 19 to be plated. 
The operation of the holder is now explained. In order to align and set a 
plurality of objects 19 on the rack base, one end 64 of the object 19 may 
be positioned on the support step 55 and the other end 65 on the support 
step 61. One end of the object 19 is received by the elevated portion 66 
(FIG. 13) and the horizontal portion 67 of the support step 55 while the 
other end 65 is received by the elevated portion 68 and the horizontal 
portion 69 (FIG. 12). Looking at this structure from above (FIG. 11), the 
corner 70 of the other end 65 is snugly inserted into a triangular concave 
portion 62. This triangular concave portion 62 can receive objects 19 
having different lengths and widths, and if the two stopper screws 59 are 
somewhat loosened and the mobile holder 54 is moved in the direction of 
the length of the objects 19, 71 utilizing the orifice 58, still more 
suitable support for various objects 19, 71 may be obtained. If there is 
formed a second orifice 72 in the direction of X at the positions where 
the opposing sides 51a, 51 b cross the cross bars 52a, 52b and 52c, 
adjustment both for the above mentioned orifice 58 and the second orifice 
72 becomes possible. 
Another embodiment of the present invention is shown in FIGS. 14 and 15. 
This embodiment provides the mobile holder 54 is supported movably in the 
direction of the width Y of the objects 19, 71 to be plated. In other 
words, two slits 74 are formed on the cross bar 73, and stopper screws 75 
passing through the orifice 58 of the holder 54 and said slits 74 are 
used. According to this embodiment, the mobile holder 54 may be moved in 
the direction of the width Y in addition to that of the length X of the 
objects 19, 71. When the holder 54 is moved in the direction of the width 
Y, the one end of the objects 19, 71 may be supported at an arbitrary 
position along the support step 55 which is continuously provided in the 
direction of the length of the fixed holder 53, thereby facilitating 
positioning of the objects 19, 71 against the plating tank 2 as shown in 
FIGS. 1 and 6 at desired positions in the horizontal direction. 
As has been explained above, the present invention comprises the plating 
tank having positioning means and having nozzles jetting the plating 
liquid over the portion to be plated on the object to be plated; 
A support carriage provided with a carrier base is engaged movably with a 
pair of rails which extend above the plating tank, and a rack base having 
a holder for objects to be plated is suspended and supported from the 
carrier base in a manner to allow ascent and descent freely; 
A pressure means is provided with a pressure member having a mask on its 
bottom which freely contacts the upper surface of the objects to be plated 
and being attached to the lower end of the rod of the pressure cylinder, 
and with a case which encloses the side of the pressure member and is 
attached thereto with its length in the vertical direction made to be 
movable, the case having a positioning means provided on the outer side to 
cooperate with the positioning means of the plating tank, and a lead wire 
intended as a cathode extends below said mask between the two outer sides 
of the case with its position variable. Thus, it is quite easy to align 
the position by the object to be plated as regards the plating tank, and 
to speedily conduct the plating, particularly partial plating by jetting 
the plating liquid, as the lead wire as a cathode is contacted with the 
upper surface of the object to be plated and as the whole object is 
pressed downwardly by the mask. Any irregularities in the alignment and 
support of the plurality of objects to be plated may be suitably corrected 
by the mask provided in the pressure member and the lead wire provided in 
the case. As the mask ascends before the lead wire, the latter acts to 
hold down the objects to be plated and prevents them from ascending with 
the mask, it is quite useful for the plating process where a plurality of 
rectangular shaped objects to be plated are processed at one time. 
In addition to the above mentioned advantages, the support carriage may be 
used to keep the descending distance for the holder long as well as to 
cause the same to abut against the first mask in the plating tank, and to 
cause the same to enter into the plating tank, if necessary. Thus, the 
diverse utility of the apparatus results in the plating line where various 
types of plating tanks are combined, thereby increasing the design freedom 
for the apparatuses for the whole plating line and also facilitating 
easier use because of the fine adjustment made possible for positioning of 
the holders. 
When the rack base for the support carriage is constructed as shown in 
FIGS. 10 to 15, the fixed holder can support one end of the objects having 
different sizes and widths while the mobile holder can support the corner 
portions of the other end of the objects having different widths and/or 
lengths in the concave portion. Thus, the apparatus can support 
diversified types and shapes of objects to be plated, and can easily 
adjust the position of the objects as against the plating tanks, or more 
directly the jet holes on the first mask, thereby greatly enhancing the 
utility value of the apparatus.