GB2038567A - A device for making temporary electrical connections to an electrical assembly - Google Patents
A device for making temporary electrical connections to an electrical assembly Download PDFInfo
- Publication number
- GB2038567A GB2038567A GB7850126A GB7850126A GB2038567A GB 2038567 A GB2038567 A GB 2038567A GB 7850126 A GB7850126 A GB 7850126A GB 7850126 A GB7850126 A GB 7850126A GB 2038567 A GB2038567 A GB 2038567A
- Authority
- GB
- United Kingdom
- Prior art keywords
- chamber
- electrical assembly
- electrical
- probes
- support
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000000523 sample Substances 0.000 claims abstract description 47
- 239000012528 membrane Substances 0.000 claims abstract description 30
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 244000043261 Hevea brasiliensis Species 0.000 claims description 2
- 229920003052 natural elastomer Polymers 0.000 claims description 2
- 229920001194 natural rubber Polymers 0.000 claims description 2
- 239000000463 material Substances 0.000 claims 1
- 230000000712 assembly Effects 0.000 description 4
- 238000000429 assembly Methods 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 238000007789 sealing Methods 0.000 description 4
- 229920001971 elastomer Polymers 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000000284 resting effect Effects 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000010948 rhodium Substances 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 229920002050 silicone resin Polymers 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/02—General constructional details
- G01R1/06—Measuring leads; Measuring probes
- G01R1/067—Measuring probes
- G01R1/073—Multiple probes
- G01R1/07307—Multiple probes with individual probe elements, e.g. needles, cantilever beams or bump contacts, fixed in relation to each other, e.g. bed of nails fixture or probe card
- G01R1/07314—Multiple probes with individual probe elements, e.g. needles, cantilever beams or bump contacts, fixed in relation to each other, e.g. bed of nails fixture or probe card the body of the probe being perpendicular to test object, e.g. bed of nails or probe with bump contacts on a rigid support
- G01R1/07328—Multiple probes with individual probe elements, e.g. needles, cantilever beams or bump contacts, fixed in relation to each other, e.g. bed of nails fixture or probe card the body of the probe being perpendicular to test object, e.g. bed of nails or probe with bump contacts on a rigid support for testing printed circuit boards
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
Abstract
A device for making temporary electrical connections to an electrical assembly 1, e.g. a printed circuit board, comprises an insulating support 4 for the assembly 1 and a chamber 15 closed by an elastic membrane 17. On evacuating the chamber 15 the membrane 17 forces the assembly 1 towards electrical probes 10 which extend through perforations 5 in the support 4 to make the temporary electrical connections with contact areas 3 of the assembly 1. <IMAGE>
Description
SPECIFICATION
A device for making temporary electrical connections to electrical assemblies and a method of making such connections
This invention relates to a device for making temporary electrical connections to an electrical assembly, particularly but not exclusively for connecting a printed circuit assembly to a test system and further relates to a method of making such connections.
A known device of this kind comprises a jig unit in the form of a chamber with an upper face comprising an aperture. The electrical assembly is located over the aperture to close the chamber. Within the jig unit and protruding above the aperture there is mounted a plurality of conductive probes which may be, for example, connected to a test system. The jig unit is connected to a vacuum pump so that when the pressure is suddenly reduced in the jig unit the electrical assembly seals the chamber. As the pressure outside the chamber is greater than that inside it the electrical assembly is forced towards the conductive probes which engage electrical contact areas on the underside of the electrical assembly.
The contact areas are in turn electrically connected to circuit components on the upper side of the electrical assembly. Thus a temporary electrical connection is made between the electrical assembly and the test system until the pressure in the chamber is raised to its initial value when the electrical assembly adopts its original position. The electrical assembly may then be exchanged for another similar electrical assembly which is to be tested.
With such a device it is necessary that the electrical assembly is capable of sealing the jig unit effectively. Thus, any apertures in the electrical assembly must be closed before the jig unit can be evacuated and consequently any apertures designed to accommodate locating pins in the jig unit must themselves be sealed by the locating pins. In addition, in order to facilitate the sealing of the edges of the aperture the circuit components may not be located near the edge of the electrical assembly. The pressure in the jig unit must be reduced suddenly to effect the sealing of the chamber and because of the inevitable leak of pressure at the edges of the electrical assembly and through any apertures in the electrical assembly it is necessary to use a high power vacuum pump to maintain an adequately reduced pressure in the jig unit.
When an electrical assembly is mounted on such a device and the pressure in the jig unit is reduced the magnitude of the force exerted on the electrical assembly differs from point to point due to the uneven distribution of the probes. This tends to cause a flexing of the electrical assembly which may suffer permanent deformation.
Although each jig unit may be used any number of times in conjunction with electrical assemblies comprising identical distributions of circuit components a different jig unit capable of maintaining a reduced pressure must be used for each different electrical assembly.
In the event that a connection between a probe and the test system is found to be broken access must be gained to the interior of the jig unit to rectify the fault. Access is difficult as the jig unit is made in such a way as to be able to maintain a reduced pressure.
According to a first aspect of the present invention there is provided a device for making temporary electrical connections to an electrical assembly, comprising an elastic membrane which forms at least a part of one wall of a chamber, an insulating support for the electrical assembly, means for mounting the support below the membrane, and conductive probes which co-operate with perforations in the support such that when the pressure in the chamber is changed the membrane forces the electrical assembly towards the probes which extend through the perforations to make temporary electrical connections with contact areas of the electrical assembly.
In a device in accordance with the invention the electrical assembly does not seal any part of the chamber. Consequently the electrical assembly may comprise apertures not only for accommodating locating pins but for any other purpose, for example to accommodate cirrcuit components from other electrical assemblies which eventually may be mounted above or below it. The apertures for the locating pins do not need to be sealed by the pins. Additionally as the edges of the electrical assembly do not play any part in the sealing of the chamber the circuit components may be located near the edge of the electrical assembly and so the surface area of the electrical assembly may be employed more efficiently.
Because the electrical assembly is not required to seal the chamber a device in accordance with the invention is more readily capable of maintaining a reduced pressure than known devices. Consequently a sufficiently low pressure can be maintained within the chamber using a low power vacuum pump.
In one form of a device in accordance with the invention a jig unit is formed by the support and a further member which has a face in which the probes are rigidly mounted and mutually insulated, said support is resiliently mounted on said face, said member comprising an electrical connector having electrical connections to said probes.
In a first type of a device in accordance with the invention the jig unit comprising the support is mounted outside the chamber below the elastic membrane so that when the pressure in the chamber is increased the elas tic membrane forces the electrical assembly towards the probes to make the electrical connections with the contact areas of the electrical assembly. In a second type of device the chamber comprises sealable access means for permitting the jig unit comprising the support, to be mounted within the chamber below the membrane such that when the chamber is sealed and the pressure in the chamber is reduced the membrane forces the electrical assembly towards the probes which connect with the contact areas of the electrical assembly, the support being removable from said chamber.Preferably, the elastic membrane forming at least a part of one wall of the chamber constitutes a lid of the chamber to which access is facilitated.
The jig unit may be used any number of times in conjunction with electrical assemblies comprising identical distributions of circuit components. A different jig unit is used for each different electrical assembly. The jig unit itself does not need to be able to maintain a reduced pressure and so the probes and electrical connections thereto may be readily accessible. When the jig unit is not subjected to the reduced pressure in the chamber it is preferable that the upper end of each probe is situated within a perforation in the support so that each probe does not protrude above the support. In this way the jig unit affords protection to the probes when it is not in use.
According to a further aspect of the invention there is provided a method of making temporary electrical connections to an electrical assembly including the steps of
mounting the electrical assembly on an insulating support having perforations to cooperate with conductive probes, and
changing the pressure in the chamber so that an elastic membrane forming at least a part of one wall of the chamber forces the electrical assembly towards the probes which extend through the perforations to make the temporary electrical connections with contact areas of the electrical assembly.
Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is a cross-sectional view of a device for making temporary electrical connections to an electrical assembly in accordance with the invention;
Figure 2 is a cross-sectional view of a device of Fig. 1 taken on the line ll-ll' of Fig.
1 and
Figure 3 is a cross-sectional view of a further device in accordance with the invention.
The electrical assembly to which temporary connections are to be made is a printed circuit board 1 which has components 2 mounted on one side.
The components 2 are electrically connected to contact areas in tthe form of contact pads 3 on the other side of the printed circuit board 1.
The device of Figs. 1 and 2 includes an insulating support 4 on which the printed circuit board 1 is to be mounted. The support 4 is in the form of a flat plate having perforations 5 and may be made of, for example, a silicone resin bonded fibre. The printed circuit board 1 is held in position by means of locating pins 6 on the support 4 which cooperate with appropriately shaped slots in the printed circuit board 1.
For the sake of clarity the Figures show the printed circuit board 1 at some distance above the support 4. In practice the printed circuit board 1 is resting on the support 4.
When the printed circuit board 1 is in position the contact pads 3 are located directly above the perforations 5. The support 4 is resiliently mounted on a member, which may be in the form of a box 7. The resilient mounting may be effected, for example, by means of coil springs 9 around guide posts between the support 4 and the box 7. There may be, for example, four springs 9 situated at the corners of a rectangular support 4. The box 7 has a face 8 in which conductive probes 10 are rigidly mounted and mutually insulated. The probes 10 may be resiliently retractable so that when pressure is app!ied to the portion 1 Ob of the probe 10 it will retract into the portion 1 Oa and when the pressure is removed it will return to its original position.
The probes 10 which may be made of, for example, steel plated with rhodium, are mounted so that they co-operate with the perforations 5 but so that in the undisturbed position the upper end of each probe 10 is situated within a perforation 5 and does not protrude above the support 4. In this way the support 4 protects the probes 10 when the device is not in use. The probes 10 are electrically connected by means of a multiwire cable 1 3 to a connector 11 situated in the wall 14 of the box 7. The box 7 with the conductive probes 10 and the connector 11, together with the support 4 constitute a jig unit 1 2 which may be inserted into a chamber 15.
The chamber 1 5 has an elastic membrane 17, which may be made of natural rubber and which is mounted in a clamping frame 1 8 which entirely surrounds the rubber membrane 1 7. The membrane 1 7 and clamping frame 1 8 together form a lid 20 which has a hinge 1 9 along one wall of the chamber 1 5.
When the lid is raised the jig unit 1 2 can be easily removed from or inserted into the chamber 1 5. When the lid 20 closes the chamber 1 5 a reduced pressure may be maintained in the chamber 1 5 using a vacuum pump 21 connected to the chamber.
When the jig unit 1 2 is inserted into the chamber 1 5 the electrical connector 11 in the box 7 mates with a complimentary electrical connector 1 6 in a wall of the chamber 1 5.
The connector 1 6 may be connected to a test system which may be, for example, an automatic test system 22 for applying various electrical tests to the components 2 of the printed circuit board 1.
When a printed circuit board 1 is to be tested the lid 20 of the chamber 1 5 is raised and the jig unit 1 2 is inserted into the chamber and a connection is made between the connectors 11 and 1 6. The printed circuit board 1 is then mounted on the support 4 and is held in position by means of the locating pins 6.The lid 20 is then closed to seal the chamber 1 5 and the pressure in the chamber 1 5 is reduced, for example in a gradual manner, by means of the vacuum pump 21 so that a difference in pressure is established across the membrane 1 7. The elastic membrane 1 7 is deformed so as to reduce the volume of the chamber 1 5. As the pressure is further reduced the deformation of the membrane 1 7 continues and eventually the membrane 1 7 forces the printed circuit board 1 towards the probes 10. The support 4 is forced towards the face 8 of the box 7 so that the probes 10 extend through the perforations 5 to contact the contact pads 3 of the printed circuit board 1.The printed circuit board remains in a flat attitude because of the nature of the support 4 on which it is located and an equal force tends to be applied to each of the probes 10. The probes 10 may be resiliently retractable so that any excess force applied to the printed circuit board 1 would cause the probes 10 to retract while a good electrical contact is maintained between the probes 10 and the pads 3. Thus the components 2 on the printed circuit board 1 become connected to the automatic test system 22.
Various electrical tests may be applied to the components 2, for example, to check the resistance of a component 2 by applying a potential difference across a component 2 and measuring the consequential current flow through it. When all of the required tests have been completed the pressure in the chamber 1 5 may be raised to its original value, and so the rubber membrane 1 7 returns to its undisturbed position as does the support 4, the
printed circuit board 1 and the probes 10.
The lid 20 is then raised and the printed circuit board 1 exchanged for a similar board which is to be tested.
When a further printed circuit board having a different configuration of components and contact pads is to be tested the jig unit 1 2 is replaced by a similarly constructed jig unit but with the probes located appropriately for the further printed circuit board. tn this way each type of printed circuit board to be tested will
require a different jig unit. However the
probes of a jig unit not being used are protected by the insulating support.
A further embodiment of a device in accordance with the invention is shown in Fig. 3.
In this modification the jig unit 1 2 is mounted outside a chamber 35 below the elastic membrane 1 7 of the chamber 35. The chamber 35 contains a fluid which may be liquid or gas. After mounting the printed circuit board 1 on the jig unit 1 2 the fluid pressure in the chamber 35 is increased, for example, in a gradual manner, by means of a pressure pump 31, so that a difference in pressure is established across the membrane 1 7. The elastic membrane 1 7 is thus deformed to force the printed circuit board 1 towards the probes 10 which extend through the perforations 5 in the support 4 to make the temporary electrical connections with the contact areas 3 of the printed circuit board 1, as has been described in the previous embodiment.
It should be noted that it is not necessary to have a separate jig unit for each printed circuit board, having a different configuration of components and contact pads as a jig unit comprising a matrix of conductive probes may be used. In this way the distribution of conductive probes is such that when making temporary electrical connections to a printed circuit board some of the probes may be redundant. These redundant probes, however, will be eniployed when temporary electrical connections are to be made to a different printed circuit board for good electrical contact the end of the probe which contacts the contact pad of the printed circuit board may take on different forms. In one form this end may be pointed, in another it may be castellated.
Claims (9)
1. A device for making temporary electrical connections to an electrical assembly, comprising an elastic membrane which forms at least a part of one wall of a chamber, an insulating support for the electrical assembly, means for mounting the support within the chamber and below the membrane, and conductive probes which co-operate with perforations in the support such that when the pressure in the chamber is changed the membrane forces the electrical assembly towards the probes which extend through the perforations to make the temporary electrical connections with contact areas of the electrical assembly.
2. A device as claimed in Claim 1, in which a jig unit is formed by the support and a further member which has a face in which the probes are rigidly mounted and mutually
insulated, said support is resiliently mounted on said face, said member comprising an electrical connector having electrical connections to said probes.
3. A device as claimed in Claim 1 or
Claim 2, in which the chamber comprises
sealable access means for permitting the sup
port to be mounted within the chamber below the membrane such that when the chamber is sealed and the pressure in the chamber is reduced the membrane forces the electrical assembly towards the probes which connect with the contact areas of the electrical assembly, the support being removable from said chamber.
4. A device as claimed in Claim 3, in which the sealable access means is a lid of the chamber, the lid comprising the elastic membrane.
5. A device as claimed in any of the preceding Claims, in which the material of the elastic membrane is natural rubber.
6. A device as claimed in any of the preceding Claims, in which the support comprises location pins to co-operate with appropriate slots in the electrical assembly.
7. A method of making temporary electrical connections to an electrical assembly including the steps of
mounting the electrical assembly on an insulating support having perforations to cooperate with conductive probes, and
changing the pressure in the chamber so that an elastic membrane forming at least a part of one wall of the chamber forces the electrical assembly towards the probes which extend through the perforations to make the temporary electrical connections with contact areas of the electrical assembly.
8. A device for making temporary electrical connections to an electrical assembly substantially as herein described with reference to the accompanying drawings.
9. A method of making temporary electrical connections to an electrical assembly substantially as herein described with reference to the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7850126A GB2038567B (en) | 1978-12-28 | 1978-12-28 | Device for making temporary electrical connections to an electrical assembly |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7850126A GB2038567B (en) | 1978-12-28 | 1978-12-28 | Device for making temporary electrical connections to an electrical assembly |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2038567A true GB2038567A (en) | 1980-07-23 |
| GB2038567B GB2038567B (en) | 1982-12-01 |
Family
ID=10501966
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7850126A Expired GB2038567B (en) | 1978-12-28 | 1978-12-28 | Device for making temporary electrical connections to an electrical assembly |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2038567B (en) |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2490350A1 (en) * | 1980-09-12 | 1982-03-19 | Thomson Csf | Vacuum type connector for PCB and test appts. - uses sheet glued onto frame forming cover placed around circuit |
| US4463310A (en) * | 1980-07-11 | 1984-07-31 | Rca Corporation | Apparatus for detecting the presence of components on a printed circuit board |
| GB2146849A (en) * | 1983-09-17 | 1985-04-24 | Marconi Instruments Ltd | Electrical test probe head assembly |
| FR2559588A1 (en) * | 1984-02-14 | 1985-08-16 | Inf Milit Spatiale Aero | Element for testing the electric connections of a printed circuit board, device and test methods using such an element |
| US4536051A (en) * | 1981-10-21 | 1985-08-20 | Marconi Instruments Limited | Electrical interface arrangements |
| US4551675A (en) * | 1983-12-19 | 1985-11-05 | Ncr Corporation | Apparatus for testing printed circuit boards |
| US4769596A (en) * | 1985-04-23 | 1988-09-06 | Faucett Dale L | Printed circuit board tester |
| EP0427883A1 (en) * | 1986-10-11 | 1991-05-22 | Microelectronics and Computer Technology Corporation | Zero insertion force electrical connector |
| EP0950901A3 (en) * | 1998-04-14 | 2002-09-11 | ABB PATENT GmbH | Test device for an electronic apparatus, especially an overload relay |
| CN118818266A (en) * | 2024-09-12 | 2024-10-22 | 上海聚跃车电检测技术有限公司 | A SOT chip high temperature working life detection device |
-
1978
- 1978-12-28 GB GB7850126A patent/GB2038567B/en not_active Expired
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4463310A (en) * | 1980-07-11 | 1984-07-31 | Rca Corporation | Apparatus for detecting the presence of components on a printed circuit board |
| FR2490350A1 (en) * | 1980-09-12 | 1982-03-19 | Thomson Csf | Vacuum type connector for PCB and test appts. - uses sheet glued onto frame forming cover placed around circuit |
| US4536051A (en) * | 1981-10-21 | 1985-08-20 | Marconi Instruments Limited | Electrical interface arrangements |
| GB2146849A (en) * | 1983-09-17 | 1985-04-24 | Marconi Instruments Ltd | Electrical test probe head assembly |
| US4551675A (en) * | 1983-12-19 | 1985-11-05 | Ncr Corporation | Apparatus for testing printed circuit boards |
| FR2559588A1 (en) * | 1984-02-14 | 1985-08-16 | Inf Milit Spatiale Aero | Element for testing the electric connections of a printed circuit board, device and test methods using such an element |
| US4769596A (en) * | 1985-04-23 | 1988-09-06 | Faucett Dale L | Printed circuit board tester |
| EP0427883A1 (en) * | 1986-10-11 | 1991-05-22 | Microelectronics and Computer Technology Corporation | Zero insertion force electrical connector |
| EP0950901A3 (en) * | 1998-04-14 | 2002-09-11 | ABB PATENT GmbH | Test device for an electronic apparatus, especially an overload relay |
| CN118818266A (en) * | 2024-09-12 | 2024-10-22 | 上海聚跃车电检测技术有限公司 | A SOT chip high temperature working life detection device |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2038567B (en) | 1982-12-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |