Plug-type connector module carrying a printed circuit board

The invention pertains to a plastic plug-type connector module which carr a printed circuit board made of ceramic. A plurality of plug members each have a rear projecting end soldered to a contact member made from a spring material, and have another portion embedded by injection molding in an insulating carrier body. The contact members in turn make contact with edge contact surfaces of the printed circuit board. In order to simplify the manufacture and to achieve soldering guaranteeing reliable contact, part of a perforated band from which the contact member is cut off is left in place. This part is also used to solder the contact member to the plug member. In order to align the surface of the printed circuit board as exactly as possible parallel to a first, flat surface of the module, there are provided molded locally limited elevations with different heights on a second flat surface which carries the printed circuit board. The height is determined after measurement of the distance between the first and second surfaces in such a way as to achieve compensation. The printed circuit board is glued to the second surface.

BACKGROUND OF THE INVENTION 
The present invention pertains to a plug-type connector module carrying a 
printed circuit board and, in particular, a plug-type connector having a 
plurality of plug elements which are connected to a printed circuit board 
mounted thereon. 
Plug-type connector modules are used, for example, in the electronic fuel 
injection systems of automobiles, where the mixture enrichment during 
start, warm-up and acceleration is controlled electronically. The air-fuel 
ratio is influenced by means of a start flap. A second actuator on the 
throttle valve provides for the correct charging. A so-called throttle 
valve potentiometer which is connected with the throttle valve shaft by 
means of a coupling is used to indicate the position and the movement of 
the throttle valve. The printed circuit board of the plug-type connector 
module essentially consists of a potentiometer with a resistor strip 
located between two terminals and a parallel collector strip, both of 
which are contacted with a sliding contact. The voltage is supplied and 
the tapped voltage is transmitted to the electronic system by means of a 
plug-type connection. A device of this general type for detecting the 
operation of a throttle valve of a carbureator is described in West 
Germany patent publication DE-PS No. 3,029,321. A throttle valve which is 
connected with the sliding contact of a potentiometer is located in the 
suction channel of the carbureator. The tapped voltage is sent via an 
amplifier to two scanning and interception circuits which in turn are 
connected with an operation amplifier comparator. The output voltage is an 
indicator of the angular velocity of the throttle valve. When the throttle 
valve stops or rotates in the plug-type connector module-site direction, 
the output voltage of the comparator disappears. 
A throttle valve potentiometer is already known which consists of a plastic 
insulating body which carries a ceramic plate with a resistor strip and 
with a collector strip as an applied printed circuit. A plug connector 
part is injection molded in the insulating body. This part consists of a 
projecting plug member and a rear contact member which serves the purpose 
of electrically connecting the plug member with the printed circuit. The 
plug member is a flat plug or a round plug made of dimensionally stable 
material. However, the contact member consists of a relatively soft spring 
material. One of the ends of the contact member is welded to the flat 
plug, from which the material of the insulating body is injection-molded 
around it. The other end of the contact member fits into perforations of 
the ceramic substrate and is soldered there by hand to edge contact 
points. When a round plug is used, the contact member is inserted into a 
centric cavity of the round plug, soldered at the free end and 
subsequently ground off, which is relatively labor-intensive. The contact 
member also has an arc-shaped deformation in order to better compensate 
the differences in the expansion of the material under the effect of 
temperature variations. Since the contact member consists of a relatively 
soft spring material, difficulties can arise due to unintended bending of 
the contact member during the injection-molding process. The manual 
soldering of the contact member to the edge contact points in the 
perforations is a source of contact uncertainty which is manifested in a 
higher failure rate. 
The insulating body consists of a base with a flat first surface. From this 
surface rises a table mountain-like carrier part on whose second surface 
the printed circuit is disposed. The second surface or the printed circuit 
should lie as exactly parallel to the first surface as possible. However, 
since the insulating body is made of plastic, it is subject to the 
ordinary technological shrinkage tolerances which are dependent on the 
shape of the body. Measurements have shown that the deviations amount to 
more than 100 um (microns). In addition, the ceramic plate of the printed 
circuit is not perfectly flat either. However, the tolerances here are 
only about 10 um. The printed circuit is held in place on the carrier part 
by an adhesive. This adhesive has the property of contracting due to 
shrinkage, such that mechanical stress is generated in the printed 
circuit. It should be borne in mind in this connection that the range of 
application can extend to as high as 150.degree. C. Since the second 
surface is not exactly parallel to the first surface, and since the 
surface of the printed surface is aligned to the first surface, it may 
occur that the printed circuit fits snugly on the carrier part in one area 
of the first surface, while in another area it may have a gap in excess of 
100 um. Even though this is compensated by a thicker adhesive layer, the 
adhesive mass does not harden but must follow the temperature variations. 
It can also happen that the adhesive mass is squeezed out and causes 
contamination in the areas where the printed circuit fits the carrier part 
snugly. 
A soldered tab for printed circuits whose end is shaped as a clamp is 
already known from West Germany patent publication DE-OS No. 2,849,610. At 
the edge this clamp is pushed onto the printed circuit. Part of the clamp 
carries a solder globule which melts under the action of heat and 
establishes electrical connection between the solder tab and the edge 
contact point of the printed circuit. The solder tabs are attached to a 
one-piece perforated band. After the solder tabs are soldered, the sliding 
contact is cut. A conductor can subsequently be soldered to the 
perforations. 
SUMMARY OF THE INVENTION 
The object of the present invention is to provide an improved plug-type 
connector module in the form useful for a throttle valve potentiometer or 
the like. The connector module can be used with round plugs or flat plugs 
and is designed to provide for simple but reliable soldering for both the 
contact member/plug member point and the contact member/printed circuit 
point, using a simple ceramic substrate for a printed circuit board 
without edge-contacting perforations. 
In accordance with the above object, there is provided an apparatus, and 
method of making same, comprising a plug-type connector module. An 
insulating carrier body has a first lower surface, and a parallel upper 
surface for carrying a printed circuit board, for example a board 
containing elements of a potentiometer. There are a plurality of plug 
connection parts, each having a front plug member with at least a portion 
embedded within the body and a lower prong portion extending out of the 
bottom of the body; and a flexible contact member which connects at one 
end to the plug member and at the other end to the printed circuit board. 
The contact members are formed on a band which has a base portion with an 
opening (or perforation) at one end of each such base member. Upon 
assembly, each contact member is cut from the band so as to provide at one 
end the part containing an opening, or hole, the hole being adapted of a 
size as to accommodate the upper end of the front plug member which is 
soldered there to the contact member.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
An insulating carrier body is designated by 1 in FIGS. 1 and 2. The carrier 
body has an oblong, e.g., substantially rectangular base 16 on whose top 
side there are provided a table mountain-like carrier part 20 and, 
approximately opposite on the lower side, an extension 27. A recess 23 is 
also provided on the lower side which serves as a support for a shaft. One 
elongated hole 18, 19 is provided in each of the four corners of the base 
16, which holes are used for adjusting and subsequently fastening the 
insulating carrier body. 
A printed circuit board 2 in the form of a rectangular ceramic plate, 
having a strip resistor 10 applied thereon, e.g., by the screen printing 
method, is disposed on the carrier part 20. Both ends of the strip 
resistor 10 are connected with edge contact surfaces 9 through conductor 
strips 12 extending along the edge of the printed circuit board. These 
conductor strips consist of conducting silver and they are also applied by 
screen printing. Parallel to the strip resistor 10 extends a collector 
strip 11. To prepare it, a strip of conducting silver is first applied, 
after which it is topped by a strip resistor preferably from the same 
resistor paste from which the strip resistor 10 was prepared. Since the 
conducting silver strip and the superjacent resistor strip are connected 
with each other electrically over the entire length, a collector strip 11 
with a low ohmic resistance is thus obtained. This method was selected to 
prepare the collector strip in order to provide a longer life element, 
since the silver strip by itself is not as abrasion-resistant as the strip 
resistor. The corresponding sliding contact which establishes an 
electrical connection between the strip resistor 10 and the collector 
strip 11 is not shown in the Figures. The collector strip itself is 
connected electrically with an edge contact surface 32 via conductor 
strips and a protective resistor. 
As is apparent from FIG. 2, the strip resistor 10 consists of two sections, 
the narrower section having at least partly a subjacent silver strip at 
its end in the vicinity of the conductor strips. The broader section which 
is the actual resistor section extends only over a relatively narrow 
angular segment relative to the axis of the shaft as the fulcrum point of 
the sliding contact, which said axis is located in the recess 23, so that 
exact setting and adjustment are necessary. 
The printed circuit 2 is positioned exactly on the surface of the table 
mountain-like carrier part 20 by means of an adjusting pin 22 molded to 
the carrier part and which reaches through a round hole 33 in the printed 
circuit 2 (see also FIG. 3). On the side of the carrier part 20 opposing 
the adjusting pin 22 there are provided edge stops 30 projecting at the 
edge (see also FIG. 7), on which the printed circuit board 2 rests. The 
exact position of the printed circuit board 2 is thus defined. 
Three round plug members 3 are also embedded by injection molding during 
the manufacture of the insulating carrier body. These plug members 3 are 
prepared from a round stock by turning. The embedding by injection molding 
is carried out together with the shaping of the entire insulating carrier 
body in such a way that the thick section projects at the bottom from the 
molded extension 27. As is apparent from FIG. 4, the rectangular extension 
27 has projecting lugs 29 at each side, by means of which the socket 
holding the plug members can be snapped on and held in position. 
A recessed chamber 24 is positioned on the top side of the base 16 in the 
carrier part 20 above the extension 27. A section of the plug member 3 
which is thinner than the thick section on the extension extends into this 
chamber. This thinner section is bent and led out through a hole 26 in the 
wall (FIG. 4). The end 31 of this thinner section tapers further compared 
with the thinner section, so that it can be easily introduced into a 
perforation 7 of band 6. 
The band 6, made of spring material with the cut-out contact members 5, is 
shown in FIG. 3 in a perspective view. The free end 13 of each contact 
member 5 has either a symmetrical or, as is shown in FIG. 5, an 
asymmetrical contour relative to the mid-plane of the clamp contour. The 
printed circuit board 2 is pushed into the free ends 13 of the contact 
members 5, clamped and soldered in the solder bath, so that the contact 
members 5 are connected with the edge contact surfaces 9, 32 of the 
circuit board 2 electrically and mechanically. After soldering, the 
contact members 5 are cut off from the band 6 by hand in such a way that a 
part 8 of the band 6 is left with one perforation 7. The perforation 7 is 
located exactly in line with the contact member 5. After the contact 
members 5 have been cut off, the contact members are provided with an 
arc-shaped deformation 15. This deformation serves to compensate the 
differences in the expansion of the material during broad temperature 
variations. It is also within the invention to provide the arc-shaped 
deformation 15 before the contact members are cut off. 
For assembly, the perforations 7 of the contact members 5 are simply pushed 
over the ends 31 of the plug members 3, the printed circuit board 2 is 
then mounted on the surface 36 of the carrier part, whereby the side of 
the printed circuit board on which the edge of the contact surfaces 9, 32 
are located come to rest at the edge stop 30. In addition, the mounting is 
carried out in such a way that the hole 33 receives the adjusting pin 22. 
The contact members 5 are finally soldered to the plug members 3 without 
difficulties, because the contact members 5 and the ends 31 of the plug 
members project from the hole 26 in the outside wall 25 of the chamber. 
Another example of a plug-type connector module is shown in FIGS. 5 and 6. 
In contrast to the first embodiment in which a round plug member 3 is 
used, a flat plug member 4 is used in this embodiment. This plug member 4 
is embedded in one piece in the insulating carrier body 14 by injection 
molding. FIG. 6 shows a section through the insulating carrier body 14 
after the injection molding and before the rear part of the plug member 4, 
provided with predetermined bending points, is bent and before the printed 
circuit board 2 is mounted. The shapes of the base 17 and the carrier part 
21 correspond to the other example. The recess 23 is also provided. Unlike 
the first embodiment, the extension 28 on the lower side of the base fits 
a receiving socket. However, snap-in fastening is provided here as well. 
To install the plug-type connector module as a potentiometer for a 
carburetor setting, it is necessary for the surface of the printed circuit 
board 2 to be as parallel as possible to the surface designated by 35 in 
FIGS. 1, 7 and 8. Deviations by up to 80 um are tolerated. Due to the 
differences in the shrinkage of the plastic, the deviations at the surface 
of the carrier part 20 are far greater than 150 um during the manufacture 
of the insulating carrier body. An adhesive mass 40 (FIG. 9) which remains 
elastic instead of hardening is used to fix the printed circuit board 2 on 
the carrier part 20. This adhesive mass has the property of pulling the 
printed circuit board to itself due to its intrinsic shrinkage, so that 
the mechanical stresses are generated in the ceramic plate. This ensures 
reliable contact. In order to compensate the above-mentioned variations, 
the distance between the first surface 35 and the second surface 36 on the 
carrier part is measured optically in various points on the surface. The 
distance is selected to be somewhat smaller than the nominal distance. The 
difference is compensated by a plurality of elevations which have 
different heights, corresponding to the shrinkage. Experiments have shown 
that the optimum value of the height is about 0.1 um. Such molded-on 
elevations are designated by 37 and 38 in FIG. 7. They have a round 
wart-like shape. Since these elevations are in an insert of the injection 
mold, their height can easily be determined later. Instead of the 
wart-like shape, the elevations 39 may also be in the form of short webs, 
as is shown in FIG. 8. 
On a greatly enlarged scale, FIG. 9 shows the unevenness of the second 
surface 36 and the different heights of the elevations 37 and 38 which 
compensate it. 
The molding of the elevations 37, 38 and 39 has the advantage that the 
adhesive mass 40 is distributed evenly under the ceramic plate and is not 
squeezed out on the sides on pressure, so that contamination is also 
avoided in this manner. If there were no elevations, it should be 
necessary to apply a much stronger force for pressing and positioning the 
ceramic plate. Due to the fact that there are elevations, the adhesive 
mass is able to flow easily into the spaces between the elevations during 
pressing, so that a much weaker pressing force is needed. This also 
diminishes the risk of mechanical damage to the ceramic plate, e.g., in 
the form of hairline cracks. Furthermore, the presence of the elevations 
also makes it possible to use an adhesive mass which is not particularly 
stable in volume, i.e., which undergoes greater shrinkage, because the 
plate is ultimately supported by the elevations and is held by the 
adhesive mass.