Temperature Stabilizer For Integrated Circuits

Abstract

A self-regulating heater for integrated circuits and the like is removably carried in a connector assembly. The connector assembly includes a housing which on one side is adapted to receive an integrated circuit unit or the like and which on the other side removably receives in a force fit a base plug which in turn is adapted to be plugged into a circuit board. The heater includes a heating element composed of material having a positive temperature coefficient of resistance. Contacts are provided on the heating element which are in resilient spring connection with heater terminals mounted in the base plug. By reaction the heating element is pressed against a heater plate also carried within the connector assembly. A rim of the heater plate is supported upon the margin of an opening or window in the housing so that an integrated circuit unit or the like mounted on the housing is placed in heat-exchange relationship with the heater plate whereby the temperature of the integrated circuit unit or the like is stabilized. Interchange may readily be made between various heater elements to provide desired changes in the regulated temperature.

Description

Integrated circuit performance is prone to be undesirably affected by ambient temperature variation. It has been the practice heretofore to build temperature-regulating devices within the cavities of integrated circuit units. This unduly burdened such units. Moreover, changes in controlled temperature could not be accomplished in any simple manner.

By means of the present invention a temperature stabilizer is provided which is not a permanent part of the integrated circuit unit which it serves. Repeated connections and disconnections of an integrated circuit with a circuit board may readily be accomplished without involving complications in making heater connections. Changes in heaters may also be easily made.

Referring to the drawings,

FIG. 1 is an exploded view in perspective of parts of the stabilizer, an integrated circuit unit being shown at the extreme left;

FIG. 2 is an inside face view of the base plug shown at the extreme right of FIG. 1;

FIG. 3 is a longitudinal section taken on line 3-3 of FIG. 2;

FIG. 4 is a plan view of the base plug without its electrical connectors;

FIG. 5 is a front elevation of FIG. 4;

FIG. 6 is a cross section taken on line 6-6 of FIG. 4;

FIG. 7 is a plan view of the outside face of a housing;

FIG. 8 is a cross section taken on line 8-8 of FIG. 7;

FIG. 9 is a front elevation of FIG. 7;

FIG. 10 is a left end view of FIGS. 7 and 9;

FIG. 11 is a longitudinal section taken on line 11-11 of FIG. 7;

FIG. 12 is a plan view of a heating element including its contacts;

FIG. 13 is a front elevation of FIG. 12;

FIG. 14 is a right end view of FIG. 12;

FIG. 15 is a plan view of the heating element of FIGS. 12--14 nested in a dished heater plate to form a complete heater;

FIG. 16 is a cross section on line 16-16 of FIG. 15, the dished heater plate being shown in longitudinal section;

FIG. 17 is a face view of an assembly of the housing on the base and illustrating the exposure of the heater plate;

FIG. 18 is a front elevation of FIG. 17;

FIG. 19 is a cross section (except for heater assembly TR) on line 19-19 of FIG. 17, parts being shown in elevation, and showing in addition the application of an integrated circuit unit, the temperature of which is regulated; and

FIG. 20 is an enlarged view of an individual spring terminal and jack, showing in solid lines the shape in which it is manufactured and in phantom its sprung shape as assembled with the base.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings. The drawings are considerably enlarged over the sizes of the actually very small parts.

Referring to FIG. 1, there is shown at the extreme left a conventional so-called 14-pin dual in-line integrated circuit unit C. This has opposite lines of terminal pins 1. At the extreme right of FIG. 1 is shown a base plug P composed of a body 2 of insulating material from which extend two heater terminals 3 and fourteen operating terminals 5, further details of which will be described below. The number of operating terminals is arbitrary.

At H is shown a housing composed of insulating material and formed for removable force-fit assembly with the body 2 of plug P. Housing H has an opening or window 7 defined by flanges 43 and flanked by rows of openings 9 for receiving the pins 1 of the integrated circuit unit. Within the body 2 is a heater element R composed of a bar 11 of semiconductive material having the above-mentioned PTC anomaly. It has terminal contacts 13 soldered thereto. Between the heater R and the housing H is located a heater plate T having a dished portion 15 for the reception of the heater. It is flanged as shown at 17. The dished portion 15 of the heater plate fits into the window 7 of the housing H. Its flanged portion 17 rests upon the inside margins of the window 7. Upon assembly under force-fit of the housing H with body 2 of the plug P, the heater R becomes nested in the dish 15 of the heater plate T. This nested assembly becomes a heater unit sandwiched between the housing H and the body 2. The dished portion 15 of the plate T becomes exposed in the window 7 and the heater R becomes connected with the heater terminals. The friction provided by the force-fit is sufficient to prevent separation under action of springs 23 but not enough to prevent manual separation when desired.

FIGS. 2--6 illustrate details of the plug P. It has a flat wall 19 through which the heater terminals 3 extend, as shown in FIGS. 2 and 3. To insure a secure connection heater terminals 3 may be staked to body 2. The insides of these terminals are located in a pocket 21 and on shoulders 22 support light compression springs 23. The longitudinal sidewalls 25 of the pocket 21 are formed exteriorly with ribs 26 notched as shown at 27 (FIGS. 4--6). The walls 25 are formed with flared recesses 29 connected with the notches 27. The notches as described are for the reception of spring clips 31, such as illustrated in greatly enlarged form in FIG. 20. Each springy strip is composed of conductive material such as copper. Its unsprung V-shape is as indicated in solid lines in FIG. 20. This V-shape is adapted to have its side portions sprung together as shown by the phantom lines 33 in FIG. 20. The sides are formed with loops 30 and flared ends 32. When sprung together each such operating terminal will then have a neck portion 35 thereof for springing placement in a notch 27. This holds each terminal part 5 in place and produces a jack portion 37 in each notch 27 in addition to forming a terminal 5. In FIGS. 4--6 the body portion 2 of the plug P is shown without any terminal or jack parts in place, whereas in FIGS. 1--3 the terminals 5 and jacks 37 are shown in assembled position.

Referring to FIGS. 7--11, details of the housing H are illustrated. It has sidewalls 36 the insides of which fit flush with the outsides of the walls 25 and the outside edges of the jacks 37, thus preventing escape of the spring terminal and jack parts 5 and 37. The housing H also has end walls 39 which frictionally fit into notches 41 at the ends of body 2. The sidewalls 36 of housing H are inwardly flanged as shown at 43 to form the window 7. The openings 9 are located in these flanges and are flared on their outsides as at 44 so as to form entry guides for the rows of pins 1 of the integrated circuit unit C.

In FIGS. 12--14 are shown details of the heater element R. This comprises the bar 11 composed of semiconductive material having the PTC anomaly, such as doped barium titanate (BaTiO.sub.3), barium strontium titanate (BaSrTiO.sub.3), barium lead titanate (BaPbTiO.sub.3) or the like. Each material provides a self-regulated temperature under the constant voltage of the heater circuit of the circuit board. The barium lead titanate provides the highest temperature of the three noted. Each contact 13 is formed with a contact pad 45 on one face and an extending side strip 47. These are soldered to the bar 11. The contacts 45 are near the ends of the bar 11 for contact with the conductive springs 23 of the heater terminals 3. The contacts 45 and side strips 47 supply voltage across the bar, which due to the PTC anomaly maintains a substantially constant temperature.

Shown in FIGS. 15 and 16 is the heater plate T composed of black anodized aluminum which provides it with an insulated surface. The bar 11 is adhered in the dished part 15 by suitable means such as epoxy resin. The flanged portions 17 engage the inside margins of the window as illustrated in FIGS. 17--19. The contact pads 45 engage the springs to maintain this engagement and to deliver heating voltage and current from the heating circuit in the circuit board. Thus, the bar 11 will become resistance heated to and maintain substantially a constant temperature because of its PTC anomaly.

As shown in FIGS. 17 and 18 when the housing H and the base plug P are assembled in force-fit frictional engagement, the heater assembly TR becomes pressed by the springs 23 so that the flat dished portion 15 of the heater plate is resiliently located and presented in the window 7. As seen in FIG. 19 housing H, upon assembly, locks heater assembly TR against base plug P. The assembly also places the openings 9 for the reception of the integrated circuit pins 1 over the internal jacks 37 forming parts of the exterior terminals 5. Then when, as shown in FIG. 19, the integrated circuit unit C is plugged in, its inner face 49 will engage the exposed part 15 of heater plate T as the pins 1 engage the jacks 37. In FIG. 19 is diagrammatically shown the integrated circuit connections 51 between opposite pins 1. One pin 1 shown in one jack 37 is illustrated by dotted lines in FIG. 19. Others have not been illustrated to avoid confusion in the longitudinal section.

It is to be understood that the assembled device as shown in FIG. 18 may be plugged into and out of an appropriate circuit board. If desired, the base P when plugged into the board may be permanently soldered into place. In either case the device may still be disassembled for substitution of one heater or another having the desired regulated temperature characteristic. The circuit board may be either of the operational type or test type. In the former case, the device prevents temperature variations in the connected integrated circuitry caused by ambient temperature changes. In the latter case the device may be used for so-called "burning-in" of newly manufactured integrated circuits, which means subjecting them for a period of time to a certain temperature to stabilize them. The device may also be used as a heat test socket for testing circuit parameters of various integrated circuits.

It is to be understood that, while the separability of the housing and plug parts H and P for substitution of heaters is a desirable feature, if separability is not desired, they may be permanently joined as with a suitable adhesive, or by integral molding around the heater assembly.

It may be remarked that the heating element exhibits moderate conductivity at temperatures below its stabilized temperature. As the temperature approaches the stabilized temperature, the conductivity of element 11 decreases rapidly. The application of a substantially fixed voltage to the heater results in fast warmup with no temperature override. This is due to the marked conductivity change in the control temperature. For example, in one form of the device, warming up from -55.degree. C. ambient, the device will draw about 6 watts for 30 seconds at 24 volts. It will stabilize in about 21/2 minutes, reducing its power requirement to about 11/2 watts steady-state at -55.degree. C. The device adjusts its steady-state requirement as dissipation conditions change. Steady-state power, for instance, decreases linearly with increasing ambient to about 0.3 watts at 60.degree. C. ambient.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims

I claim:

1. A temperature stabilizer for circuit devices having conductive leads, comprising plug means, a PTC anomaly heater in the plug means, said heater having an exposed heating surface, said plug means including heater terminals extending therefrom, said heater terminals being connected to said heater, springs electrically and removably connecting the heater terminals with said heater, means for removably mounting circuit devices including jacks in the plug means, additional terminals connected to said jacks respectively and extending from the plug means, said jacks being arranged adjacent to the exposed heating surface for the reception of circuit device leads and to removably place a circuit device having said leads in heat-exchange relationship with the exposed portions of said heater.

2. A temperature stabilizer for pin-type integrated circuits, comprising a plug element, an enclosing housing connected therewith forming an assembly, said housing formed with a window therein, a PTC anomaly heater located in the assembly and having a heating surface disposed at said window, heater terminals extending from said plug element and electrically connected with said heater, jacks located in the assembly, operating terminals extending from said jacks respectively to the exterior of the plug element, said housing having openings for receiving and directing pins of an integrated circuit into said jacks, whereby an integrated circuit may be brought into heat-exchange relationship with said portions of the heater exposed in said window.

3. A temperature stabilizer according to claim 2 wherein there is a separable connection between the housing and the plug element whereby they may be separated and reassembled for effecting heater substitutions.

4. A temperature stabilizer according to claim 3 wherein the connections between said heater terminals and the heater are in the forms of springs which bias the heater toward said window.

5. A temperature stabilizer according to claim 4 wherein the heater is in the form of a bar of said PTC anomaly material nested in a heater plate having a heater surface fitting within said window and flanges internally engaging the margins of the window under pressure from said springs.

6. A temperature stabilizer for multiple-pin, dual in-line integrated circuits, comprising a hollow rectangular plug element, a rectangular housing connected therewith, said housing forming a rectangular window, a PTC anomaly heater located between the housing and the plug element and having a rectangular heated surface extending through said window, heater terminals extending from said plug element, springs electrically connecting the heater terminals with said heater, rows of jacks located between the housing and the plug dually aligned on opposite sides of the heater, operating terminals extending from said jacks and dually aligned on the exterior of the plug element, said housing having dually aligned openings on opposite sides of said heated surface for guiding pins of an integrated circuit into said jacks, whereby an integrated circuit may be brought into heat-exchange relationship with said exposed portions of the heater.

7. A temperature stabilizer according to claim 6 wherein there is an openable force-fit between the housing and the plug whereby they may be separated and reassembled for effecting heater substitutions.

8. A temperature stabilizer according to claim 7 wherein the heater is in the form of a dished plate with a bar of said PTC anomaly nested therein, said heater plate having flange means seating behind the margin of said window under pressure from said springs.

9. A temperature stabilizer for integrated circuits, comprising an insulating base, heater terminals and operating terminals extending from said insulating base for plugging into a circuit board, an insulating body connected with said base, said operating terminals being formed within the body as jacks, a PTC heater element within the body, said heater element having contacts engaged through springs with said heater terminals, said body having a window, a dished and flanged heater plate having at least a part of its dished portion extending through said window and its flanged portion engaging the inside margin of the window, said heater element being nested in said dished portion of the heater plate, said body having openings aligned with said jacks for the reception of pins of an integrated circuit and their direction into said jacks, said heater plate being in close heat-exchange relationship with the integrated circuit when its pins are applied to the jacks through said openings.

10. A temperature stabilizer made according to claim 9 wherein the base, the body and the heater element are separable for replacement of the heater element.