U.S. patent number 3,778,755 [Application Number 05/304,090] was granted by the patent office on 1973-12-11 for self-staking wire grip terminal.
This patent grant is currently assigned to Berg Electronics, Inc.. Invention is credited to Richard L. Marks.
United States Patent |
3,778,755 |
Marks |
December 11, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
SELF-STAKING WIRE GRIP TERMINAL
Abstract
A wire grip circuit board terminal having a cylindrical body, a
circumferential flange on one end and collapsable fingers on the
other end. The collapsable fingers permit staking of the terminals
to circuit boards of different thicknesses. The terminals are
staked to circuit boards without the necessity of special staking
tooling for collapsing the fingers. The ends of the fingers grip
wires inserted into the terminals.
Inventors: |
Marks; Richard L.
(Mechanicsburg, PA) |
Assignee: |
Berg Electronics, Inc. (New
Cumberland, PA)
|
Family
ID: |
23175006 |
Appl.
No.: |
05/304,090 |
Filed: |
November 6, 1972 |
Current U.S.
Class: |
439/853; 411/38;
439/877 |
Current CPC
Class: |
H01R
12/58 (20130101) |
Current International
Class: |
H05K
3/32 (20060101); H01r 009/08 () |
Field of
Search: |
;339/217R,217S,217PS,217JP,22R,22A,22C,22L,22T,219R,219F,258R
;29/203,625,626 ;85/71,37 ;24/94,73D,95,96,213,219 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Champion; Marvin A.
Assistant Examiner: Hafer; Robert A.
Claims
What I claim as my invention is:
1. A circuit board eyelet adapted to be staked in a circuit board
hole comprising a hollow generally cylindrical body, flange means
at one end of the body having a central longitudinal axis, and a
plurality of spaced staking fingers extending away from the other
end of the body with the free ends of the fingers grouped together
in converging relation adjacent the axis of the eyelet, each finger
including a sharp outer bend located between the body and the
finger ends defining an apex facing generally inwardly toward said
axis and a sharp inner bend defining an apex facing generally
outwardly away from said axis located between the body and the
outer bend, whereby during staking the portions of the fingers
between the body and the outer bends are pivoted away from said
axis and into contact with the adjacent edge of the circuit board
hole, the ends of the fingers forming means for receiving and
holding a lead inserted through the eyelet body.
2. A circuit board eyelet as in claim 1 wherein each finger
includes a first flat portion extending from the body to said inner
bend, a second flat portion extending from the inner bend to the
outer bend and a third flat portion extending form the outer bend
to the end of the finger.
3. A circuit board eyelet as in claim 2 wherein in each finger the
outer bend is located further from a line extending from the tip of
the finger to the junction between the finger and the body than the
inner bend.
4. A circuit board eyelet as in claim 3 wherein the width of each
finger at the inner bend is less than the width of the finger at
the outer bend.
5. A circuit board eyelet comprising a generally cylindrical body
having a central longitudinal axis, an outwardly extending flange
at one end of the body, and a plurality of collapsable fingers
extending from the other end of the body, each finger including a
sharp outer bend located approximately midway along the length
thereof defining an apex facing generally inwardly toward said axis
and a sharp inner bend located approximately midway along the
portion thereof between said body and said outer bend defining an
apex facing generally outwardly, away from said axis, said outer
bend being located further from a line extending from the tip of
the finger to the junction between the finger and the body than
said inner bend whereby upon axial collapse of the eyelet
positioned in the circuit board hole said legs first collapse about
said outer bend to move said leg portions outwardly against the
circuit board hole to confine the eyelet in the hole.
6. A circuit board eyelet as in claim 5 wherein said eyelet
includes a set of wire grip fingers extending from outer edges of
said flange into the opening at one end of the body, the ends of
such fingers being spaced closely together to receive and hold a
lead inserted into the body.
Description
Wire grip circuit board eyelets of the type shown in U.S. Pat. Nos.
3,368,188 and 3,504,328 are well known in the art. These terminals
include a cylindrical body, a circumferential flange at the upper
end of the body and a circumferential flange member at the bottom
of the body. The eyelets are inserted in holes formed through the
thickness of the circuit board with the circumferential flange
member extending outwardly of the board and are staked to the board
by generally conical flaring tooling engageable with the
circumferential flange member to flare it outwardly of the body
about the lower corner of the circuit board hole. This staking
operation is illustrated in U.S. Pat. Nos. 3,538,581, 3,571,924 and
3,574,935. All of the patents relating to the evelets per se and to
staking of the eyelets to circuit boards are assigned to the
assigner of the present invention. The circuit board eyelets may
include wire grip fingers located generally within the thickness of
the circuit board. U.S. Pat. No. 3,156,517 discloses a solder well
terminal staked to a circuit board with wire grip fingers located
in the well to one side of the circuit board.
The invention relates to an improved self staking wire grip
terminal similar to the cylindrical circuit board eyelets of the
type illustrated in U.S. Pat. Nos. 3,368,188 and 3,504,328. The
eyelet includes a flange for engaging the top of the circuit board,
a cylindrical body portion which fits into a circuit board hole,
and a number of collapsable fingers extending downwardly from the
body beyond the circuit board. During staking the circuit board is
held against an upper flat staking surface so that the upper eyelet
flanges are sandwiched between the surface and the top of the
circuit board. A lower flat staking surface is then moved toward
the upper surface so that it engages the free ends of the fingers.
As the surfaces close the fingers buckle outwardly of the circuit
board hole to engage the lower corner of the hole so that the
eyelet is confined in the hole by the upper flange and the
outwardly bent portion of the fingers. After staking the free ends
of the fingers are close to each other and serve to hold a lead
inserted into the eyelet in place prior to and during a soldering
operation. If desired, additional wire grip fingers may be provided
at the upper flange so that the eyelet includes two sets of wire
grip fingers. After staking, leads are inserted in the eyelets and
are held by the fingers. The circuit board may then be soldered to
form electrical connections between the leads and circuit pads on
the board.
During staking the eyelet fingers are deformed to attach the eyelet
to the circuit board without the necessity of the conventional
conical staking heads. This means that eyelets can be staked to a
circuit board with improved reliability. In production, circuit
board holes are formed through circuit boards with a relatively
large tolerance concerning their location on the board. The
conventional conical staking tooling is provided on the staking
plate in alignment with the design or intended location of each
circuit board hole. In actuality the circuit board hole may be
shifted laterally on the board an appreciable distance from the
design location. This means that during staking the lower
cylindrical flange member is offset with respect to the staking
tool and that the member is imperfectly deformed during staking.
Eyelets staked in this manner are so imperfectly attached to the
circuit board that they must be replaced. This problem is
eliminated with the present circuit board eyelet because the
specialized staking tooling is not required.
The collapsable legs of the present eyelet enable the eyelet to be
staked to circuit boards of different thicknesses without impairing
the physical connection between the eyelet and the board. Also the
wire grip ends of the fingers serve to retain leads in the eyelet
without regard to the thickness of the board. This advantage is
important since the thickness of mass produced circuit boards
varies appreciably.
Other objects and features of the invention will become apparent as
the description proceeds, especially when taken in conjunction with
the accompanying drawings illustrating the invention, of which
there are two sheets.
IN THE DRAWINGS
FIG. 1 is a side view of a terminal strip illustrating a number of
eyelets according to the invention;
FIG. 2 is a view similar to that of FIG. 1 illustrating an
individual eyelet held by the strip;
FIG. 3 is a view taken along line 3--3 of FIG. 2;
FIG. 4 is a partially broken away view illustrating a terminal in a
circuit board hole between a pair of staking surfaces;
FIGS. 5 and 6 are views similar to FIG. 4 illustrating the staking
operation;
FIGS. 7, 8 and 9 are similar to FIGS. 4, 5 and 6 but illustrate the
staking operation on a circuit board of greater thickness than that
of FIG. 4;
FIGS. 10, 11 and 12 are also similar to FIGS. 4, 5 and 6 but
illustrates the staking of an eyelet on a circuit board having a
thickness less than the circuit board of FIG. 4;
FIG. 13 is a view of the top of the eyelet taken along line 13--13
of FIG. 6;
FIG. 14 is a sectional view taken through a staked eyelet
illustrating a lead held therein by the ends of the staked
fingers;
FIG. 15 is a view similar to that of FIG. 14 illustrating an
embodiment of the invention in which the upper flange includes a
number of wire grip fingers; and
FIG. 16 is a view taken along line 16--16 of FIG. 15 without the
lead illustrating the upper wire grip fingers.
Circuit board eyelets 10 illustrated in FIG. 1 are preferably stamp
formed from thin sheet metal stock and may be secured at regular
intervals to a thin carrier strip 12 by severable connecting
portions 14. Each eyelet includes a cylindrical body 16 with a
flange 18 on the end thereof adjacent the strip 12. As illustrated
in FIGS. 3 and 13, flange 18 includes five tabs 20 arranged around
the end of body 16. Portion 14 connecting the eyelet to the strip
12 is an extension of one of the tabs 20. A longitudinal seam 22
extends along the side of the body 16 away from tab 14. The body 16
need not be cylindrical but may have a prismatic or other cross
section.
Four collapsable fingers 24 extend from the end of the body 16 away
from flange 18 with the free ends or finger tips 26 gripped closely
together around the longitudinal axis of the terminal. The tips of
the fingers may be slightly spaced from each other, as illustrated
in FIG. 1 or may actually touch each other, as illustrated in FIG.
3. The body 16 is cut away between adjacent fingers at 28 to
facilitate bending of the fingers during staking of the
terminal.
As illustrated at FIGS. 2 and 4, the fingers each include three
generally flat sections 30, 32 and 34 interconnected by an inwardly
directed or inner sharp bend 36 and an outwardly directed or outer
sharp bend 38. Flat section 30 extends from body 16 to inner bend
36, flat section 32 extends from inner bend 36 to outer bend 38 and
flat section 34 extends from an outer bend 38 to finger tip 26.
Outer bend 38 is located approximately midway along the length of
the finger and the inner bend 36 is located approximately midway
along the length of the portion of finger extending between the
body and the outer bend. Outer bend 38 is positioned to the outside
of the axis of the finger and is further away from the axis than
the inner bend 36. The axis of the finger is defined by a line
extending from finger tip 26 to the junction between section 30 and
body 16.
As illustrated best in FIG. 4, the width of the fingers 24 varies
along the length thereof. The width remains constant from body 16
along flat portion 30 and approximately one half of flat portion
32. The width of the lower part of portion 32 increases to a
maximum width just above bend 38. This width is maintained through
approximately one half of portion 34 with the width of the free end
of portion 34 decreasing to relatively narrow tips 26. This
decrease in width permits close positioning of the tips adjacent
each other in surrounding relationship to the longitudinal axis of
the terminal.
Terminals 10 as described may be fitted within circuit board holes
40 formed through the thickness of circuit board 42, as illustrated
best in FIG. 4. The flat upper flange 18 rests flush upon printed
circuit pad 44 with the terminal body 16 within the hole and
fingers 24 extending down from the body and out of the bottom of
the hole. A circuit pad may be provided at the bottom of the hole.
After the terminals 10 are positioned in holes 40 in the circuit
board, the board is held against a flat upper staking plate 46 so
that the flanges 18 are confined against the top of the circuit
board. Staking is accomplished by raising a flat lower staking
plate 48 up against the projecting ends of fingers 24 to collapse
the same, as illustrated in FIGS. 5 and 6, and thereby stake the
terminals to the circuit board.
In FIG. 4, staking surface 48 is below terminal tips 26. As the
plate is raised it engages the tips and forces the same toward each
other to assure that the tips engage each other and prevent further
lateral movement of the tips. After the tips have been brought
together, continued upward movement of plate 48 collapses the
fingers 24 about outer corners 38. The outer corners bend because
they are located outwardly of the finger axes. The inner corners 36
do not bend. With the collapse of the fingers resulting from
bending at corners 38, the flat portions 30 and 32 are pivoted
outwardly of the hole 40 about their juncture with terminal body
16.
Outward pivotal movement continues until the fingers engage the
bottom corner of the hole 50 as illustrated in FIG. 5. The
thickness of circuit board 42 is such that this engagement occurs
at inner corner 36. After engagement between the fingers and corner
50, further upward movement of staking plate 48 collapses the
portions of the fingers below the circuit board, as shown in FIG. 6
which illustrates the terminal fully staked to the circuit board.
Staking plates 46 and 48 are then opened to permit removal of the
circuit board 42 with staked terminals 20 thereon. Leads 52 may be
inserted into the staked terminals as illustrated in FIG. 14. The
leads force apart the wire grip ends of the fingers. The ends of
the fingers securely hold the leads in place for a subsequent
soldering operation. The soldering operation fills the eyelet
bodies with solder to form a reliable electrical connection between
the leads and the printed circuit pad on the circuit board. Eyelets
10 are particularly adapted for wave soldering in which case the
bottom surface of the circuit board is exposed to a wave of molten
solder which flows into the eyelet through openings between the
fingers, up through the eyelet body and on to the circuit board pad
at the top of the circuit board to form the desired solder joint.
The fingers hold the lead in place and prevent lead movement during
soldering.
The lower staking surface 48 is flat and does not require
specialized tooling for staking the terminals. This means that the
staking operation is carried out as desired and is not affected by
off-center circuit board holes. Also the cost of staking tooling is
appreciably reduced by eliminating the necessity of providing
tooling in the lower plate for each individual eyelet in the
circuit board. The tolerance for positioning circuit board holes
may be decreased to permit location of a hole in a greater area on
the circuit board without affecting the reliability of the staking
operation. This represents a saving in circuit board costs.
The staking steps shown in FIGS. 4, 5 and 6 illustrate the staking
of an eyelet 10 to a circuit board 42 having a nominal thickness
for the eyelet. The eyelet may also be staked to circuit boards
having a thickness less than that of the nominal thickness circuit
board or to circuit boards having a thickness greater than that of
the nominal thickness circuit board. FIGS. 7, 8 and 9 illustrate
staking of an eyelet 10 to a circuit board 54 having a thickness
greater than that of circuit baord 42. FIGS. 10, 11 and 12
illustrate staking of the same eyelet to a circuit board 56 having
a thickness less than the thickness of circuit board 42.
Referring now to FIGS. 7, 8 and 9, a terminal 10 is positioned in a
circuit board hole 58 extending through board 54 with the upper
flange 18 held flush on the top of the board by upper staking plate
46. The lower flat staking plate 48 is raised to bring the finger
tips 26 together. Further raising of the plate collapses the
fingers 24 about outer bends 38 in a manner similar to the collapse
during the initial staking of an eyelet 10 to circuit board 42. As
flat portions 30 and 32 of each finger are bent outwardly away from
body 16, portion 32 engages the lower corner 60 of hole 58. Further
upward movement of staking plate 48 results in a collapse of the
exposed portions of fingers 24. The staking operation is completed
when the lower staking plate reaches the position of FIG. 9 and the
portions of fingers 24 projecting outwardly of hole 58 are
collapsed as illustrated. As in the staking operations illustrated
in FIGS. 4 through 6 and FIGS. 10 through 12, the fingers are held
tightly against the bottom corner of the circuit board hole during
the final collapse of the exposed finger portions. After the
staking tooling has opened and the board and terminals are removed
from the staking apparatus, leads may be inserted into the terminal
between the wire grip ends of the fingers prior to the soldering
operation of the type previously described.
FIGS. 10, 11 and 12 illustrate staking a terminal 10 to a circuit
board having a thickness less than that of circuit board 32. The
staking operation is essentially the same as that previously
described with the exception that during the initial staking step
flat portion 30 is brought into engagement with the lower corner 62
of circuit board hole 64. Further upward movement of the lower
staking plate collapses the fingers about the corner 62, as
illustrated, in essentially the same manner as shown in FIGS. 6 and
9. Again leads may be inserted into the staked eyelets on board 56
prior to a soldering operation.
During staking of a terminal 10 to any of circuit boards 42, 54 and
56 the outward bending of the legs brings the narrow width portion
of the legs 24 into contact with the lower corner of the circuit
board hole. This contact between the lower corner of the hole and
the minimum width portion of the legs assures that the legs bend
about the corner at the contact point to securely hold the eyelet
to the circuit board. The legs are weakened at the contact point
because of the reduced width in order to assure the desired bending
at the lower hole corner during staking.
The movement of the staking tooling 46 and 48 in staking eyelets 10
to circuit board 42, 54 and 56 is identical. Thus, on a production
run it is not necessary to alter the adjustment of the staking
tooling to accomodate circuit boards of different thicknesses.
FIGS. 15 and 16 illustrate a further embodiment of the invention in
which the upper flange 18 engages reverse bend wire grip fingers 66
which form extensions of tabs 20 bent back on top of the tabs and
extending over the interior of body 16. These fingers provide
additional wire grip support for retaining a lead 70 in the eyelet.
It is frequently desirable to secure a lead in place against
possible lateral movement during soldering. This is assured by
providing the spaced pair of wire grip fingers. With the exception
of the additional wire grip fingers 66, the eyelet 68 of FIGS. 15
and 16 is identical to eyelet 10.
Circuit board holes are conventionally formed by either a drilling
or a punching operation. In both these operations it is difficult
to accurately control the diameter of the hole. The variation in
circuit board hole diameter mades it difficult to stake
conventional eyelets to circuit boards. Eyelets of the type
disclosed herein represent an improvement over conventional eyelets
in this regard since the staking legs 24 bend outwardly of the hole
until they engage the edge of the hole. Thus, a tight staked joint
is formed between the eyelet and the circuit board without regard
to the diameter of the individual hole. The tight physical
connection between the eyelet and the circuit board improves the
subsequently formed solder connection.
While I have illustrated and described preferred embodiments of my
invention, it is understood that these are capable of modification,
and I therefore do not wish to be limited to the precise details
set forth, but desire to avail myself of such changes and
alterations as fall within the purview of the following claims.
* * * * *