Apparatus for use in making a selectively vapor deposition coated tubular article

Method and apparatus for use in selectively vapor deposition coating the interior surface of a tubular article, the apparatus including a plurality of axially aligned spaced apart masks, the periphery of the masks being complimentary with the tubular article, and a vapor deposition coating means positioned between the masks for depositing a electrically conductive coating onto the unmasked area of the interior of the tubular article.

BACKGROUND OF THE INVENTION 
Discussion of Pertinent Prior Disclosures 
Interconnect sleeves for electrical connection have long been known and 
used. An example of an electrical interconnect is R. J. T. Clabburn, U.S. 
Pat. No. 3,898,389, which discloses an electrical interconnect device, the 
surface of which has been coated with a thin metallic layer. 
As the popularity for electrical interconnect sleeves has increased so has 
the need for low cost interconnect sleeves. Applicants herein have 
developed a method and an apparatus for use in making a low cost 
interconnect sleeve having a electrically conductive coating which is 
tenaciously bonded to the interior surface of same. 
In the past there have been many methods and apparatuses for applying 
conductive coatings to selected areas of articles. For example, J. J. 
Torok, U.S. Pat. No. 2,953,483 generally discloses a method and apparatus 
for vapor deposition coating the surface of an article by confining the 
article within a chamber, vaporizing the coating and electrically charging 
the coating and spraying the article with the coating on the unmasked 
portions. Torok uses a hood for application to the surface of the article. 
Torok relies upon direct contact of the mask with the article to effect 
his coating. 
Another method and apparatus for vapor deposition coatings is found in 
Deverse et al., U.S. Pat. No. 3,699,917 wherein solder is deposited onto 
the terminals of semi-conductor wafers by heating and evaporating solder 
on a single source. The solder is applied by a plurality of wire rings 
arranged in a plurality of wafer carrying tiers by exposing the evaporant 
approximately one-sixth (1/6) of each cycle and then cooling the solder by 
radiation. Trim tabs between the source and dome assure uniform 
distribution of solder on all wafers, regardless of tier location. Thus, 
the solder source rotates applying a uniform distribution (coating) of 
solder to the wafer (article). 
Another method for selectively coating articles is found in R. J. Al, U.S. 
Pat. No. 3,565,644 wherein selected portions of an article are masked and 
then fusing pulverulent particles to the surface of the article which are 
applied by a powder coating method. The article is exposed to elevated 
temperatures for a prolonged period of time to thermally fuse the coating 
in place. One embodiment, shown in FIG. 3, illustrates coating a pipe 
fitting with a powder coating. The fittings are connected by tandem by 
nipples having chamfered ends, flat sheets of cork are cut to size and 
wrapped around each nipple and secured thereto by means of adhesive or a 
wire wrapped around each sheet covering the exterior surface of the 
nipples. The exterior surface of the fittings are coated with purverulent 
coating particles after elevating the temperature. 
Nakken, U.S. Pat. No. 2,891,880 discloses a vacuum deposition process for 
producing film resistors. A helical resistance ribbon is applied to the 
surface of a tubular insulating material by use of a bimetallic helical 
mask wherein different co-efficients of expansion of the metals are used 
to hold the mask onto the insulator. It will be noticed that the interior 
walls are necessarily in contact at all times with the mask. This method 
of producing resistor rings is particularly dependent upon the precise 
contact of the tubular article with the mask. In this manner, the coatings 
applied to the tubular article are the precise thickness required. 
Although it has long been known to apply coatings to an article through a 
vapor deposition process as illustrated by the above, no one heretofore 
has discovered a method and apparatus for selectively coating the interior 
surface of tubular interconnect articles. Applicants here, have developed 
a novel method and apparatus which may be utilized in making cost 
efficient, selectively coated tubular interconnect articles as set forth 
above and as will be appreciated more fully hereinafter. 
DESCRIPTION OF THE INVENTION 
Summary of the Invention 
An apparatus for use in selectively vapor deposition coating the interior 
surface of a tubular article having a longitudinal axis. The apparatus 
comprises a pair of axially aligned spaced apart electrically insulated 
masks having opposed masking surfaces; each masking surface being 
generally planar and generally perpendicular to the longitudinal axis of 
the tubular article. The periphery of the masks are complimentary with the 
tubular article. Support means may be used to axially align and space 
apart the masks. The apparatus includes a vapor deposition coating means 
for applying an electrically conductive coating on the interior surface of 
the tubular article. The coating means may be connected to the opposed 
surfaces of the masks and positioned axially therebetween. Alternatively, 
the coating means may be wound around the support means. In an alternative 
embodiment of the apparatus, the masks may be modified so that a 
non-uniform coating may be deposited on the interior surface of the 
article. 
A method for vapor deposition coating a selected area of the interior of a 
tubular article which may be corona pre-treated. The steps comprise: 
providing a tubular article having a longitudinal axis; inserting masks 
and vapor deposition coating means within the article, the masks having 
opposed axially aligned spaced apart planar surfaces which are generally 
perpendicular to the longitudinal axis, the coating means being disposed 
axially between the opposed surfaces; evacuating the interior of the 
article between the masks; and activating the coating means to deposit, in 
a radial fashion, a generally uniform coating on the selected area between 
the opposed masking surfaces. 
It will be appreciated that an article made by the above described method 
using either of the planar mask or modified mask as will be more fully 
described hereinafter is also part of the applicants' invention. 
Objects of this Invention 
It is the primary object of this invention to provide method and apparatus 
for making cost efficient selectively coated tubular articles. 
It is another object of this invention to provide method and apparatus for 
making selectively coated tubular interconnect articles having a uniform 
coating. 
It is another object of this invention to provide method and apparatus for 
making selectively coated tubular interconnect articles having a 
non-uniform coating. 
It is a further object of this invention to provide method and apparatus 
for making selectively coated heat recoverable tubular articles wherein 
the coating adheres tenaciously to the interior surface before and after 
recovery.

DETAILED DESCRIPTION OF THE INVENTION 
With reference to the drawings, wherein like reference characters designate 
like or corresponding parts throughout the several views and referring 
particularly to FIG. 1, there is shown an apparatus in accordance with 
this invention generally designated by the numeral 10 for use in 
selectively coating tubular articles. 
The apparatus 10, includes a plurality of axially aligned, spaced apart 
masks 12. The masks are electrically insulated to prevent electrical 
discontinuity during the coating of the article. The masks are preferably 
cylindrical. However, as long as the masks ae complimentary with the 
tubular article, any shape is satisfactory, e.g. if the tubular article is 
rectangular, the masks should be rectangular. 
In an alternative embodiment, the masks may be made of a machinable 
insulating material, wherein at least one of the masks include a 
peripheral zone which is machined along dotted lines 14, as shown in FIGS. 
1 and 2. When the masks are machined in this manner, a non-uniform coating 
may be deposited on the tubular article 13, as shown in FIG. 5 and as will 
be more fully appreciated hereinafter. Applicants have found machinable 
porcelain or other ceramic materials to be especially well-suited for this 
purpose. 
In the embodiment of the apparatus 10 shown in FIG. 1, a vapor deposition 
coating means 18 is located between the masks 14 and wound about the 
internal support means 16. Applicants have found that a suitable coating 
means comprises an electrically conductive wire, such as a tungsten wire, 
coated (or wicked) with an evaporant such as silver, gold, copper, 
aluminum or the like. Further, applicants suggest using a relatively thin 
coating of evaporant. Particularly, applicants have found that an 
evaporant coating of 1000.degree. A is suitable for the purposes and 
objects of his invention as will be more fully appreciated hereinafter. 
It will be appreciated that a support means is not necessarily needed as 
long as the masks are axially aligned and spaced apart. Alternatively, the 
apparatus may include external support means (not shown) for spacing 
apart, axially aligning and supporting the masks when held in a vertical 
position as shown in FIG. 3. 
Applicants, preferably, helically wind the wire having the evaporant 
between the masks so that a relatively uniform distribution of evaporant 
is sprayed onto the interior surface of the tubular article between masks 
12. Of course, it may not always be desirable for the tubular article to 
have a relatively uniform coating. In those circumstances the mask may be 
machined at the peripheral zone as shown by the dotted lines 14 to define 
a frusto-conical or truncated paraboloid shape. The resultant masking 
surface 12 causes an uneven (or non-uniform) coating to be applied to the 
adjacent interior surface of the tubular article as shown and explained 
more fully by FIG. 5 and the accompanying description. 
The above described spraying process is known as vapor deposition. The 
conductive wire is wicked with evaporant and charged with a high 
electrical current (usually between 20-80 amps at 12 volts). The evaporant 
flashes from the wire to the unmasked area of the interior surface of the 
tubular article. As can be seen in the figures, the coating means is 
connected to a power supply 20 by electrically conductive conduit means 
22. Tungsten wire is particularly suitable as the wire structure of the 
coating means because it is able to withstand high current. However, other 
suitable wire structures are of course known, for example nichrome wire. 
FIG. 2 shows an alternative embodiment of the apparatus in accordance with 
this invention generally designated by the numeral 24, which includes 
masks 14 and a wire structure 26 between the masks. The wire structure 26, 
serves the dual function of spacing apart the masks and as a vapor 
deposition coating means defining an integral support and coating means. 
In this embodiment, the wire should be of a relatively heavy gauge. 
Applicants have found tungsten wire having a diameter between 0.010 to 
0.050 inches is preferable. 
Additionally, it is possible to utilize wire, such as tungsten, with three 
relatively thin strands wrapped together for the integral support and 
coating means embodiment. The wire is preferably helically wound to 
generate the same type of generally uniform spraying (flashing) as 
described previously. Structure 26 functions in a manner similar to the 
previously discussed coating means 18 and is shown similarly connected to 
a power source 20 through electrically conductive conduit means 22. 
With particular reference to FIG. 3, there is shown a plurality of 
apparatus 24 inside a vacuum chamber 28. The apparatus 24 are connected in 
parallel to power source 20 by electrically conductive conduit means 30. 
It will, of course, be appreciated that apparatus 10 could similarly be 
placed inside vacuum chamber 28. Tubular articles, such as 13 may be 
placed over each apparatus 10 or 24, respectively, prior to placement in 
the vacuum chamber. The vacuum chamber 28 may then be sealed and 
activated. The chamber is pumped until atmospheric conditions inside the 
chamber reach at least 1.times.10.sup.-5 torr. The power source may then 
be activated, preferably between 20-80 amps at 12 volts. The evaporant 
flashes to the tubular article 13. The vacuum may then be de-activated and 
the apparatus with the selectively coated tubular articles unloaded. 
With particular reference to FIGS. 4 and 5, there is shown selectively 
coated tubular articles 32 and 38. In FIG. 4 there is seen tubular article 
32 having an interior surface 34 which has been coated with an evaporant 
36 through method described above. It will be appreciated that mask 14 
need not be in contact with interior wall 34 to yield a selective, 
generally uniform coating 36. 
In FIG. 5 there is shown another tubular article 38 which has been coated 
with the apparatus having the peripheral zone machined along lines 14 as 
shown defining a frusto-conical or truncated paraboloid shape, depending 
upon the type of mask used. As can be seen interior wall 40 of the tubular 
article 38 includes a non-uniform, progressively thinning coating wherein 
the central portion of the coating 42 is uniform and generally thicker 
than the progressively thinning outer portion 44. 
It will of course be appreciated that the tubular article may be used as a 
heat-recoverable interconnect device. In said case, the tubular article 
should be made of a heat-recoverable material wherein substrates may be 
placed inside the article, and heat applied to form a conductive 
interconnect joint. The friction of the substrates against the interior 
coated surface of the article tends to wear off the coating. In order to 
minimize this effect, applicants have found a means for tenaciously 
bonding the coating to the interior of the tubular article. 
The article 13 may be exposed to corona discharge treatment which 
encourages micropitting immediately prior to coating. When the interior of 
the tubular article 13 is micropitted, the surface area exposed to the 
spray is increased and irregular, thereby providing a better surface for 
adhering the coating to the interior of the tubular article. Moderate 
levels of corona pre-treatment sufficient to cause micropitting without 
creating undue electrical charge build-up are preferred. Additionally, 
when the article is placed in the vacuum chamber and the pressure lowered 
to the preferred condition, further micro-pitting is encouraged. 
Additionally, the interior of the tubular article 13 is cleaned during the 
vacuum process before coating. 
The machining of the masks together with the ability to selectively coat 
without the need for direct contact of the masks to the interior surface 
of the tubular article allows applicant to apply the above described 
non-uniform coating. Thus, in addition to providing a useful apparatus for 
making cost effective selectively coated tubular articles, applicants 
provide a structure which is also useful in the making of cost effective 
selectively coated tubular interconnect articles wherein the coating is 
tenaciously bonded to the article. 
It will of course be appreciated that a selectively coated tubular article 
may be made by the following steps: providing a tubular article having a 
longitudinal axis, inserting a vapor deposition coating means and masks 
within the article, the masks having opposed axially aligned spaced apart 
planar surfaces which are generally perpendicular to the longitudinal 
axis, the coating means is disposed axially between opposed mask surfaces; 
evacuating the space in the interior surface of the tubular article 
between the masking surface; and activating the coating means by 
electrical means. 
Alternatively, a non-uniform coating may be deposited on the selected area 
of the tubular article where the masks include a peripheral zone which is 
non-perpendicular and outwardly diverging from the longitudinal axis of 
the tubular article as at the lines 14. When tenacious adherence of the 
coating is desired, the tubular article may be pre-treated with a corona 
discharge under either of the above methods. Further, the article may be 
heat recoverable under either of the above described methods when that 
type of article is desired. 
While the instant invention has been described by reference to what is 
believed to be the most practical embodiments, it is understood that the 
invention may embody other specific forms not departing from the spirit of 
the central characteristics of the invention. It should be understood that 
there are other embodiments which possess the qualities and 
characteristics which would generally function in the same manner and 
should be considered within the scope of this invention. The present 
embodiments therefore should be considered in all respects as illustrative 
and not restrictive, the scope of the invention being limited solely to 
the appended claims rather than the foregoing description and all 
equivalents thereto being intended to be embraced therein.