High density disposable printed circuit inter-board connector

A connector frame for use in the connection of electrical circuit assemblies having pins integrally connected therewith. The connector frame is a body of electrically non-conductive, thermally conductive material having one or more apertures bored through the body, said apertures being through-plated with an electrically-conductive material having a lower melting point than any of the surrounding materials. Said body also includes at least one separate aperture in which is disposed an electrically-conductive, heat-generating wire, said wire having the capacity to generate sufficient heat to melt the electrically-conductive material disposed in the apertures to form a strong electrical and mechanical bond between the pins of the electrical circuit assemblies.

TECHNICAL FIELD OF THE INVENTION 
The present invention relates to a disposable connector frame for use in 
detachably connecting a pair of electronic assemblies. 
BACKGROUND OF THE INVENTION 
Current methods of printed circuit inter-board connection utilize 
connectors which do not always provide a reliable electrical and strong 
mechanical bond due to the nature of a removable or reusable connection. 
Some prior art printed circuit board connectors often require that a large 
amount of force be exerted to connect the printed circuit boards either 
directly or through interconnecting blocks. After connection has been 
formed, the holding force of these types of printed circuit board 
connectors often makes the printed circuit boards difficult to disconnect. 
To achieve a higher degree of reliability in prior art reuseable 
connectors, a scraping action to cut through oxide buildup to form a 
positive electrical connection is required. Miniaturization of components 
is sometimes limited in the prior art due to the force and scraping action 
requirements, so the number of pins on the printed circuit boards which 
may be effectively interconnected is correspondingly limited. 
The present invention overcomes the above-enumerated problems and other 
shortcomings associated with current printed circuit board connection 
devices by providing a semi-permanent connector which forms a strong 
mechanical and electrical bond without the need of high insertion force or 
scraping action. 
SUMMARY OF THE INVENTION 
The present invention relates to a connector frame for use in the 
connection of printed circuit boards or other electronic assemblies having 
pins integrally connected therewith, the connector frame comprising a body 
of electrically non-conductive material having one or more apertures bored 
through said body, the placement of said apertures corresponding to the 
placement of the pins on the printed circuit boards, such that said pins 
are aligned with said apertures and bonded together with a low melting 
point solder heated from a heater wire. 
The present invention also relates to a connector frame for use in the 
connection of printed circuit boards and when in use disposed between a 
pair of printed circuit boards, said printed circuit boards having pins 
integrally connected therewith, said connector frame comprising a body of 
electrically non-conductive, thermally conductive material having one or 
more apertures bored through said body, said apertures being 
through-plated with an electrically conductive material having a lower 
melting point than any of the surrounding materials; the placement of said 
apertures corresponding to the placement of said pins on said printed 
circuit boards, such that said pins are aligned with and inserted into 
said apertures. Said body also includes an electrically conductive, 
heat-generating wire, said wire when energized having the capacity to 
generate sufficient heat to melt the electrically conductive material 
disposed in the apertures such that, in use, the pins are electrically and 
mechanically connected between the circuit boards by said melting 
electrically conductive material. When said wire is deenergized, said 
electrically conductive material cools and solidifies forming a 
semi-permanent electrical and mechanical bond. 
The present invention also relates to a disposable connector frame for use 
in the interconnection of printed circuit boards and when in use disposed 
between a pair of printed circuit boards, said printed circuit boards 
having one or more pins integrally connected therewith, said connector 
frame comprising a body of electrically non-conductive, thermally 
conductive, and inexpensive material, such as plastic or nylon, having one 
or more apertures bored through said body in a substantially vertical 
direction in axial alignment with the pins connected to said circuit 
boards. Said vertically disposed apertures being filled with an 
electrically conductive material having a lower melting point than any of 
the surrounding materials, such as solder and the centers of said 
apertures are drilled out to form vertical holes having an approximate 
diameter less than said apertures but greater than said pins. Each of said 
pins has a length extending through slightly less than one-half the length 
of said vertically disposed holes, such that the vertically aligned pins 
of each circuit board do not meet within the vertically disposed holes. 
Said body also includes at least one aperture in which is disposed an 
electrically conductive, heat-generating wire, said wire having the 
capacity to generate sufficient heat to melt the electrically conductive 
material disposed in the substantially vertical apertures, but does not 
interconnect with said vertically disposed apertures. 
An advantage of one embodiment of the present invention is that it is a 
zero-insertion-force connector, so the printed circuit boards are easily 
connected. 
Another advantage of one embodiment of the present invention is that it 
forms a strong electrical and mechanical bond between sandwiched printed 
circuit boards. 
Yet another advantage of one embodiment of the present invention is that no 
scraping action to cut through oxide buildup such as may be required in 
the use of current printed circuit board connectors is mandated. 
Still another advantage of one embodiment of the present invention is its 
capacity to be miniaturized to a great degree, thus allowing compatability 
with other miniaturized electrical components. 
Still another advantage of one embodiment of the present invention is its 
low cost, such that the connector may be disposable in nature. 
Still another advantage of one embodiment of the present invention is that 
connected printed circuit boards may be easily disconnected. 
The above described features and advantages, along with various other 
advantages and features of novelty, are pointed out with particularity in 
the claims annexed hereto and forming a part hereof. However, for a better 
understanding of the invention, its advantages, and objects attained by 
its use, reference should be had to the drawings which form a further part 
hereof and to the accompanying descriptive matter in which there is 
illustrated and described a preferred embodiment of the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION 
In the following detailed description of the preferred embodiment, 
reference is made to the accompanying drawings which form a part hereof, 
and in which is shown by way of illustration a specific embodiment in 
which the invention may be practiced. This embodiment is described in 
sufficient detail to enable those skilled in the art to practice the 
invention and it is to be understood that other embodiments may be 
utilized and that structural changes may be made without departing from 
the scope of the present invention. The following detailed description is, 
therefore, not be taken in a limiting sense, and the scope of the present 
invention is defined by the appended claims. 
Referring now to the drawings, there is illustrated in FIGS. 1 and 2 an 
embodiment of a connector frame 20 in accordance with the principles of 
the present invention. The body 32 of the connector block or frame 20 is 
made of an electrically non-conducting material such as nylon or plastic 
and is either cut from a bulk material or molded. In molding, the 
apertures 30 and 40 could be pre-cast or could be bored after molding. 
The connector frame 20 is depicted as being able to detachably connect two 
printed circuit boards, upper printed circuit board (PCB) 22 and lower 
printed circuit board (PCB) 24. Both upper PCB 22 and lower PCB 24 possess 
a number of pins disposed in a generally perpendicular direction to the 
substantially flat surfaces of PCBs 22 and 24 and integrally connected 
therewith; said pins hereinafter referred to as upper pins 26 and lower 
pins 28, respectively. These upper and lower pins 26,28 are in alignment 
with each other in a substantially vertical direction (perpendicular to 
the surfaces of the PCBs 22, 24 and the connector frame 20), as well as in 
substantially vertical alignment with apertures 30 bored through the body 
32 of the connector frame 20. Those skilled in the art will readily 
recognize that the PCB pins may be at angles other than perpendicular, 
such as edge connector pins protruding substantially parallel to the 
planar surfaces of the PCB's. Also, the interconnection can be made to a 
backplane or to smaller components or component carriers such as from PCB 
to backplane, PCB mother board to PCB daughter board, PCB to chip carrier, 
PCB to chip, etc. 
Apertures 30 are through-plated or filled with an electrically conductive 
material having a lower melting point than any of the surrounding 
materials; in the preferred embodiment, this material is a low-temperature 
solder such as indalloy #8. Through-plating in the preferred embodiment is 
performed by boring the apertures 30, filling said apertures with molton 
solder, then boring out the centers of the soldered holes after the solder 
solidifies, such that a coating of solder remains disposed on the walls 34 
of apertures 30. Through-plating may be performed in an alternate 
embodiment by boring the apertures 30 and inserting therein drawn solder 
having a flux filled interior sized to be slightly larger than the pins 26 
and 28. The flux flows upon application heat and opens the centers of the 
solder to form holes for accepting the pins 26 and 28. The flux serves the 
additional purpose of aiding the solder connection process as is 
well-known in the art. 
The length of apertures 30 is such that when connector frame 20 is pressed 
between upper PCB 22 and lower PCB 24, upper pins 26 and lower pins 28 
each extend into apertures 30, so that the ends 36 and 38 of the pins 26 
and 28 do not meet. This requirement ensures a strong mechanical bond 
since the surfaces of PCB's 22 and 24 are pressed and held firmly against 
the connector block 20. Those skilled in the art will recognize that the 
pins may be allowed to meet or the pins may be partially inserted at a 
cost of giving up mechanical rigidity. 
A horizontal aperture 40 disposed at a substantially 90 degree angle to 
vertical apertures 30, is also bored in the connector frame 20 of the 
preferred embodiment of the invention. Contained within and running 
through this horizontal aperture 40 is an electrically conductive, 
heat-generating wire 42, which in the preferred embodiment is formed of a 
material such as NiChrome. The wire 42 of the preferred embodiment is 
electrically insulated from both the upper and lower pins 26 and 28, as 
well as from vertical apertures 30 in which said pins 26 and 28 are 
disposed, such that the connector block 20 is heated when current is 
passed through wire 42. Heat generated by the wire 42 is conducted through 
the body 32 of the connector frame 20 in sufficient degree to melt the 
low-temperature solder disposed upon the walls 34 of vertical apertures 
30. 
Melting of the low-temperature solder within vertical apertures 30 causes 
an electrically conducting conduit to be formed between upper and lower 
pins 26 and 28, thus establishing an electrical contact between PCBs 22 
and 24. The current is removed from wire 42 and the molten solder is then 
allowed to cool, such that the electrical conduit remains. When 
disconnection of PCBs 22 and 24 is desired, current may again be 
established in the NiChrome wire 42 of the preferred embodiment, such that 
heat generated by said wire 42 will again melt the solder disposed in 
vertical apertures 30. After said solder is molten, PCBs 22 and 24 may be 
easily pulled apart. Connector frame 20 may then be discarded, a feasible 
option since the cost per unit for the construction of connector frame 20 
is very low. 
Dimensions of elements contained in the preferred embodiment of the 
invention are very small; for example, upper and lower pins 26 and 28, 
formed in the preferred embodiment of a high conductive metal such as 
beryllium copper, may be approximately 4 mils in diameter. The inertia 
diameters of the vertical apertures 30 after soldering has occurred may be 
5 mils, while the outer diameters of the apertures 30 may be 10 mil, such 
that a 5 mil in diameter coating of solder would be disposed on the walls 
of the vertical apertures 30. By selecting the aforementioned dimensions, 
a staggered spacing of 10 mil holes would allow up to 1000 holes per inch 
on a single connector. The NiChrome wire 42 could be selected on the 
current required to heat 1000 holes per inch. The size of the NiChrome 
wire would vary based on the current capacity and heat generation 
requirements. Those skilled in the art will readily recognize that a wide 
variation in the size and spacing of the holes is possible without 
deviating from the spirit and scope of the present invention as described 
in the appended claims. 
In use, the connector frame 20 is pressed between PCBs 22 and 24, such that 
pins 26 and 28 are disposed in solder-coated vertical apertures 30. 
Electrical current is then established in the NiChrome wire 42, which 
generates enough heat to melt the solder disposed on walls 34 of apertures 
30. Melting of the solder causes an electrically conductive conduit to be 
formed between pins 26 and 28, thus establishing an electrical contact 
between PCBs 22 and 24. The molten solder is then allowed to cool, such 
that the electrical contact remains. This electrical contact may be 
maintained for as long as is desired, until disconnection of PCBs 22 and 
24 is warranted. When disconnection of PCBs 22 and 24 is desired, an 
electrical current is again established in the NiChrome wire 42, such that 
the heat generated by said wire 42 will again melt the solder. After the 
solder is molten, PCBs 22 and 24 may be easily pulled apart, and the 
connector frame 20 may be discarded. 
Those skilled in the art will readily recognize a wide variety of 
variations on the preferred embodiment of the present invention which do 
not depart from the spirit and scope of the present invention. For 
example, the connector block may be bored with holes aligned at right 
angles to allow the interconnection of circuit boards meeting at right 
angles. A wide variety of angular interconnections is possible by varying 
the angles of the apertures in connector block 20. 
Connector block 20 itself need not be rectangular in shape but may in fact 
be of fewer or many sides such as an octagon allowing interconnection of a 
plurality of circuit boards. In an octagonal application, four bore holes 
could be made all of which meet at the center of the octagon-shaped 
connector block. The four bore holes could then all be filled with a low 
temperature solder allowing the interconnection of eight pins from eight 
different circuits. The pins 26 and 28 of circuit boards 22 and 24 
respectively need not be perpendicular to the surface of the circuit 
boards but may in fact be attached to the edges to allow the circuit 
boards to be inserted into multi-shaped connector blocks 20. The apertures 
34 need not be bored circular in shape but may in fact be carved or molded 
in a wide variety of shapes. The through-plating of the holes 34 may be 
accomplished by a wide variety of plating mechanisms such as 
electroplating, electrolessplating or sputtering. The plating of holes 34 
need not be complete in that a partial plating of the holes could be 
sufficient to form an electrical bond between pins 26 and 28. 
An alternate method of constructing the present invention is shown in FIG. 
3 in which a two-piece connector block 32 is comprised of an upper 
connector block piece 32a and a lower connector block piece 32b. Grooves 
50 having a V-shape or other cross-sectional shape are etched or milled 
into connector block 32. The groove 50 are placed on the connector block 
pieces 32a and 32b in a corresponding relationship. The solder sections 34 
having interior holes 30 may be placed in the grooves 50 before the 
grooved blocks 32a and 32b are fastened together by conventional means 
along the direction indicated by the arrows in FIG. 3. The solder sections 
34 may be constructed according to techniques previously described such as 
hollow cylinders of solder, through-plating, electroplating and the like. 
The NiChrome heating wire 42 may be placed in either or both of the 
connector block pieces 32a and 32b for heating during assembly and removal 
of the connector block 32. 
The heater wire 42 may be constructed as an integral non-removable portion 
of the connector blocks previously described or it could be constructed to 
be removable or replaceable. A replaceable heater wire may be advantageous 
where the possibility exists that an integrated connector wire 42 could be 
damaged or broken during the heating process. In this fashion, a connector 
block could not be removed with a break in the heater wire 42. By using a 
replaceable heater wire 42 placed in aperture of the connector block 32, 
the danger of a broken heater wire making the connector block 
non-removable can be eliminated. 
The NiChrome heater wire 42 need not necessarily be formed perpendicular to 
the holes 34 to melt the low temperature solder. The electrically 
conducting wire may be snaked in any particular fashion throughout the 
connector block as long as a sufficient heat is imparted to each 
through-plated hole 34 to allow the low temperature solder to melt. The 
heater wire 42 may be made a permanent part of connector block 20 or may 
be inserted only when required for heating. 
While the present invention has been described in connection with the 
preferred embodiment thereof, it will be understood that many 
modifications will be readily apparent to those of ordinary skill in the 
art, and this application is intended to cover any adaptations or 
variations thereof. Therefore, it is manifestly intended that this 
invention be limited only by the scope of the claims and the equivalents 
thereof.