Note: Descriptions are shown in the official language in which they were submitted.
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ELECTRICAL~Y SHIELDING
Field of the Invention
This invention relates to electrically shielding, and
more particularly, in preferred embodlments, to the coaxlal
~hielding of sprlng pins.
Backaround of the Invention
The desirablllty of shleldlng elements of electrlcal
clrcults, ln approprlate lnstances, ls well known. Coaxially
shlelded ~prlng plns for u6e ln connectlon wlth prlnted circuit
boards ("PCB~") are known.
Su-marY of the Invention
I have discovered that coaxlal 6hieldlng may be
provlded, reliably, at low expense and consi6tently wlth hlgh
~hlelded element denslty, by provldlng an lnsulator base having
shlelded element and groundlng element mountlng holes, the lnner
wall of a grounding element mountlng hole belng ln conductlve
electrlcal communlcatlon with a shield around a shlelded element
mountlng hole and spaced therefrom by lnsulatlng materlal.
Accordlng to a broad aspect of the lnventlon there ls
0 provlded an electrlcally shleldlng devlce which comprises~
a base,
said base belng formed of in~ulating materlal and havlng
thereln
a shleldJng hole and
a shleld connectlng hole,
. sald ~hleldlng hole havlng posltioned thereln
a metalllc shleld therearound,
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an insulator wlthin ~aid shield, and
an element hole in said insulator, and
said shield connecting hole having positioned therein an
electrically conductive layer, said layer being in electrical
communication with said shield.
According to another broad aspect of the invention there
i8 provided the method of fabricating a æhielding device which
comprlses forming an lnsulatlng base, provlding thereln a flrst
hole and a second hole, coating said base over said holes with a
layer of conductlve materlal, placing in said first hole an
insulatlng material with a third hole therethrough, and
electrlcally interconnecting the coatlngs in said first and second
holes.
In preferred embodlments, the insulator base is a
unltary ~tructure molded from polyphenylene sulfide reinforced
with glass and containing a multlpllcity of spring pin mountlng
holes orlented ln pairs, one sprlng pln mountlng hole of each palr
belng spaced by a polytetrafluoroethylene lnsulatlng annulus from
an electroless nlckel ghleld around the annulus, the other sprlng
pin mountlng hole of each palr belng conductlvely connected to the
~hleld by a contlnuum of the electroless nlckel.
In another aspect of the inventlon, I have dlscovered
that such a coaxlal shleldlng devlce may be provlded by formlng an
ln~ulatlng base containlng a palr of holes therethrough, platlng
the base wlth metal, removlng the metal from top and bottom
surfaces of the base, and formlng ln one of the holes an annulus
of lnsulatlng materlal. In a preferred embodlment a bllnd slot ls
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provided between the two holes before plating.
Preferred E~bodiment
Following is a description of preferred embodiments of
the device and method of the invention.
Drawing~
There is shown in:
Flgure 1 an lsometric view of a broken-away portion
showing one shleld portion of the preferred embodiment of the
device.
Flgure 2 a correspondlng lsometric view illustrating an
earlier stage ln the preferred embodlment of the method.
Flgure 3 a dlagrammatlc plan vlew of a broken away
portlon of the devlce.
Flgure 4 a plan vlew on a smaller scale of an
arrangement of sald devices.
Figure 5 a sectional view taken at 5-5 of Figure 3.
Figure 6 a correspondlng sectlonal vlew showlng a second
devlce cooperatlng wlth a flrst in order to ~ecure therebetween a
sprlng pln.
8tructure
There i~ shown ln Flgure 3 an enlarged plan vlew, and ln
Flgure 1 an lsometrlc vlew, of a portlon of one of the devlce~,
indlcated generally at 10, of the lnventlon. In use, elght of
these devlce~ 10, the lnner and outer walls 12 and 14 of whlch are
coaxlally arcuate (O.D. 10 lnches) are abutted to form an
arrangement annular ln horlzontal cro~s-sectlon, as shown in plan
vlew ln Flgure 4.
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71~
Referring to Figures 2 and 5, each devlce 10 has a base
16 formed by lnjection molding of glass-filled (40%) polyphenylene
sulfide (sold by Phillips Chemlcal Company under the trademark
RYTON R-4). ~xtending through base 16 are cylindrically annular
layers 18, 20 of dull (for better adhesion) electroless nlckel.
The layer extends ln a continuum along the floor 22 and sides 24,
26 of bllnd slot 27 and therefrom in portlons 28, 30 of
counterbore 32 and cylindrlcal portion 34 wlthin hole 36. Annular
ca~t tetrafluoroethylene lnsulator 38 ca~tlng materlal ~sold by
DuPont under the trademark TEFZEL) iB wlthln electroless nlckel
layer 18, 20 and fill~ slot 27. Hole 40 wlth counterbores 42 is
provlded ln lnsulator 38.
As ~hown in Flgure 6, two unlt~ 10 are brought together
wlth sprlng plns indlcated generally at 43 held therebetween ln
one set of counterbores 32, 42 for each sprlng pln. (Counterbores
32, 42 are provided at each end of holes 36, 40 80 that the ring
44 made up of unlts 10 may be used with either surface up, to
permlt moldlng a slngle base 16 even though two configurations of
base 16 are needed, for example alternatlng around the annulus,
one belng a mlrror lmage of the other. The rlng 44 may be held
together and down on a PCB (not shown) by screws (not ~hown), and
permlts easlly releasably connectlon therethrough wlth another PCB
(not shown).
OPeration
Current passlng through sprlng plns 43 ln lnsulator 38
18 electrically shlelded by electrodless nickel completely
therearound, the latter belng electrlcally connected wlth the
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ad~acent ground spring pin through a continuing layer of
electroless nickel. Hole 36, in which the ground spring pin is
located, thus is a shield connecting hole, in that the layer of
nickel electrically connects the pin in it to the shield of the
adjacent shielded pln.
Hethod
The device is made by first molding the base 16, giving
it an overall thickness about 0.020 inches greater than ultimately
wanted. The entire piece is then given a coating of dull
electroless nickel, which extends over top, bottom and throughout
the large and snall hole, counterbore, and slot as ~hown ln the
uncoated piece ~hown ln Figure 2. About 0.010 inch thlckness ls
then removed ~rom top and bottom, removlng wlth lt the nlckel
coating thereover. Bushing 38 is then cast.
Other E-bodi~ents
Other embodlments wlll occur to those skllled ln the
art.
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