GB2217929A - Modular interface for testing printed circuits - Google Patents
Modular interface for testing printed circuits Download PDFInfo
- Publication number
- GB2217929A GB2217929A GB8827791A GB8827791A GB2217929A GB 2217929 A GB2217929 A GB 2217929A GB 8827791 A GB8827791 A GB 8827791A GB 8827791 A GB8827791 A GB 8827791A GB 2217929 A GB2217929 A GB 2217929A
- Authority
- GB
- United Kingdom
- Prior art keywords
- planar
- electrical contacts
- interface
- printed circuit
- elements
- 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.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/28—Testing of electronic circuits, e.g. by signal tracer
- G01R31/2801—Testing of printed circuits, backplanes, motherboards, hybrid circuits or carriers for multichip packages [MCP]
- G01R31/2806—Apparatus therefor, e.g. test stations, drivers, analysers, conveyors
- G01R31/2808—Holding, conveying or contacting devices, e.g. test adapters, edge connectors, extender boards
-
- 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
- G01R1/07364—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 with provisions for altering position, number or connection of probe tips; Adapting to differences in pitch
Abstract
A modular interface for establishing electrical contact between a printed circuit and apparatus for testing the printed circuit comprises a pair of spaced planar members (1, 2) each of electrically non-conductive material with electrically conductive pins (9) extending therethrough. Corresponding pairs of electrically conductive pins (9) are interconnected by electrical conductors (10). To enable the electrical conductors (10) to be connected to the electrically conductive pins, the planar member (1) comprises frame containing a plurality of planar elements (6) each of which can be moved out of the plane of the planar member (1) to enable the electrical connections to be made. <IMAGE>
Description
INTERFACE FOR TESTING PRINTED CIRCUITS
The present invention relates to interfaces for testing printed circuits and to a method of forming such an interface.
Apparatus for testing printed circuit boards is known which comprises a bed or matrix of closely-spaced electrically conductive spring-loaded pins or probes (hereinafter called "pins") selected ones of which are electrically connectable to selected positions on a printed circuit to be tested and computer means for controlling the supply of electrical current to the selected pins according to a predetermined sequence and for comparing whether or not a circuit is established between different ones of the selected pins, and hence between different selected positions on the printed circuit being tested, with a test pattern held in memory.
With such apparatus, when a number of identical printed circuits are to be tested either the selected positions on the printed circuits to be tested are programmed into the testing apparatus or a first master" printed circuit is connected at selected positions thereon to selected ones of said pins, electrical current is supplied to the selected pins according to a predetermined sequence and a test pattern of "circuit" or "no circuits between different ones of the selected pins is stored in memory.
Thereafter the printed circuits can be rapidly tested.
The selected positions on a printed circuit board with which said selected pins are required to be electrically connected may, for example, correspond to plated-through holes in the printed circuit in which components are mounted and such selected positions do not usually correspond exactly with the positions of the pins in said bed. In consequence it is normally necessary to provide an interface for electrically connecting circuits to be tested with selected ones of said pins. Such an interface usually comprises a pair of planar members of electrically non-conductive material which are spaced apart by spacers extending therebetween.Electrical contacts, such as electrically conductive pins, are inserted through one of said planar members at selected positions thereon corresponding to selected points on the printed circuit to be tested and the other planar member has electrical contacts, such as electrically conductive pins, inserted therethrough at selected positions thereon corresponding to selected ones of said spring-loaded pins in said bed. The electrical contacts of the one planar member are electrically connected to the corresponding electrical contacts of the other planar member by electrical conductors which extend therebetween.To enable the electrical conductors to be connected between the corresponding electrical contacts of the planar members, one planar member is normally hinged at one end and said electrical conductors are normally folded adjacent said hinge so that each electrical conductor extends from its electrical contact on one planar member along the one planar member towards said hinge and then back along the other planar member to its corresponding electrical contact on the other planar member. In a typical interface there may be between one and two thousand electrical conductors.As a result, the electrical conductors, particularly the electrical conductors connecting those electrical contacts furthest from the hinge, are relatively long and the electrical conductors are closely packed, particularly in the region of the hinge, so that even when shielded electrical conductors are used transient signals are induced which can corrupt the test signals.
There is, accordingly, a need for an interface for use in testing printed circuits in which the lengths of the electrical conductors can be kept to a minimum to reduce the likelihood of transient voltages being induced and so reduce corruption of the test signals.
The present invention provides an interface for establishing electrical contact between selected points on a printed circuit and selected electrical contacts of apparatus for testing the printed circuit, the interface comprising a pair of spaced planar members of electrically non-conductive material one of which has electrical contacts extending therethrough at selected positions thereon corresponding to said selected points on the printed circuit and the other of which has electrical contacts extending therethrough at selected positions thereon corresponding to said selected electrical contacts of said testing apparatus, and electrical conductors connecting the corresponding electrical contacts of said planar members, at least one of said planar members comprising a plurality of planar elements each of which can be moved out of the plane of the planar member to enable said electrical conductors to be connected between the electrical contacts of the planar element and the corresponding electrical contacts of the other planar member.
Preferably, said planar elements are in the form of strips or slats which are arranged in parallel side-byside relationship to form said at least one planar member.
It will be readily understood that with the interface of the present invention, the electrical conductors need be of a length only sufficient to enable said planar elements to be moved out of the plane of the one planar member sufficiently to enable the electrical conductors to be connected between the electrical contacts of the moved planar element and the corresponding electrical contacts of the other planar member, and that accordingly the length of each of the electrical conductors can be kept to a minimum. In addition the electrical conductors do not all become bunched in one area, as they do adjacent the hinge in conventional interfaces.
Said planar elements may be mounted in a frame, e.g., a square or rectangular frame having opposed frame portions between which end portions of said planar elements are received and which are connected together to retain the planar elements. One of said frame portions may have locating pins or pegs thereon which engage corresponding apertures in said end portions of said planar elements. The other of said frame portions may comprise the bottom wall of a box-like enclosure having side and end walls upstanding from the bottom wall, the top of the enclosure being closed by said other planar member.
The invention also provides in combination with an interface according to the invention, an adaptor plate having slot-like apertures therein corresponding to said planar elements. Said planar elements may each have a rebate around the periphery thereof of substantially the thickness of the adaptor plate and in which the adaptor plate is received, whereby that surface of each planar element which, when the interface is in use, is directed towards the electrical contacts of the testing apparatus is in the plane of the lower surface of the adaptor plate.
For use with testing apparatus of the kind wherein vacuum pressure is used to draw the interface into tight electrical contact with said bed and the printed circuit to be tested into tight electrical contact with the interface, the adaptor plate may be adapted to make sealing engagement with sealing means of the testing apparatus and may itself comprise sealing means for sealing each of said planar elements, e.g., may comprise an endless seal surrounding each said aperture therein and adapted to cooperate with the rebate of the corresponding planar element.
As stated hereinbefore, in a typical interface there may be between one and two thousand, and in extreme cases up to five thousand, electrical contacts in one of said planar members for contacting selected spring-loaded pins in said bed of the testing apparatus. The planar members are usually formed from glass fibre reinforced plastics material.The spring pressure exerted by each selected spring-loaded pin in said bed on said planar member is usually about 6.7 ounces (189 grams) with the result that the total load imposed by the spring-loaded pins on said planar member is considerable and can cause deflection or distortion of said planar member such as to result in insufficient electrical contact between some of the electrical contacts of said planar member and the corresponding spring-loaded pins in said bed To overcome or mitigate this problem support means can be provided between said planar members which will transmit at least part of said load from said one planar member to the other planar member and so prevent or minimise deflection or distortion of the one planar member.Said support means may comprise pegs or posts mounted on one of the planar members and bearing against the other of the planar members, the support means being provided at locations subject to deformation or deflection and not occupied by the electrical contacts which extend through the planar members. Thus, for example, each of said planar elements of said at least one planar member may be in the form of a strip or slat and may have two pairs of rows of spaced electrical contacts with one pair of said rows extending along each of the longitudinal side margins thereof and the other planar member may have the electrical contacts thereof similarly arranged. Some or all of said planar elements may each have a said support means thereon which is located centrally thereof between the said two pairs of rows of electrical contacts.
The present invention further provides a method of forming an interface for use in testing a printed circuit comprising the steps of providing a pair of spaced planar members of electrically non-conductive material at least one of which comprises a plurality of planar elements each of which can be moved out of the plane of the planar member, inserting electrical contacts through each of said planar members at selected positions thereon, moving a said planar element out of the plane of the one planar member, connecting electrical conductors between the electrical contacts of the moved planar element and corresponding electrical contacts of the other planar member, and replacing the moved planar element in the plane of the one planar member.
The invention will be more particularly described with reference to the accompanying diagrammatic drawings, in which:
Fig. 1 is an exploded perspective view of an interface according to the present invention, and
Fig. 2 is a detail perspective view illustrating supports for one of the planar members of the interface.
Referring to the drawings it will be seen that the interface illustrated therein comprises a pair of spaced planar members 1, 2 of electrically non-conductive material which are mounted in a box-like sheet metal housing 3 and are spaced apart by pillars 4 extending upwardly from a locating frame 5.
material which are mounted in a box-like sheet metal housing 3 and are spaced apart by pillars 4 extending upwardly from a locating frame 5.
The planar member 1 comprises a plurality of planar elements 6 which are supported at their ends on a recessed portion 7 of a flange 8 at the bottom of the housing 3 and are located by the locating frame 5 which is supported on the flange 8 and has locating pegs (not shown) thereon which engage corresponding apertures in the ends of the planar elements 6. The locating frame 5 is secured, e.g., bolted, to the flange 8 and the planar member 2 is secured, e.g., bolted, to the pillars 4.
Planar elements 6 each have electrically conductive pins 9 extending therethrough (shown on one planar element 6 only for clarity) selected ones of which are electrically connected by insulated electrical conductors 10 to corresponding electrically conductive pins (not shown) extending through the planar member 2. The electrically conductive pins 9 are adapted to make electrical contact with electrically conductive springloaded pins 11 extending upwardly from the bed 12 of apparatus 13 for testing printed circuits. The pins 11 in the bed 12 are arranged in pairs in spaced rows as indicated digrammatically by lines 14. The pins 9 of the planar elements 6 are similarly arranged with each planar element 6 having two pairs of rows of pins, one pair along each longitudinal side margin as diagrammatically illustrated by lines 9a in Fig.2.Planar member 2 is adapted to support a printed circuit (not shown) to be tested so that selected electrically conductive pins of the planar member 2 electrically contact selected points of the printed circuit. The selected pins of the planar member 2 are in turn electrically connected to selected pins 11 by way of selected pins 9 and electrical conductors 10.
To prevent deflection or distortion of the planar elements 6 under the load imposed thereon by the springloaded pins 11, some or all of the planar elements 6 are each provided with a support means in the form of a peg or post 20. The peg or post 20 of each planar element 6 is located centrally thereof between said pairs of rows of pins 9 and is adapted to abut the planar member 2.
In the embodiment illustrated a printed circuit to be tested is drawn into tight electrical contact with the planar member 2 and the planar elements 6 are drawn into tight electrical contact with the bed 12 by vacuum pressure. To this end the interface is used in combination with an adaptor plate 15 which is adapted to make sealing engagement with a seal 16 around the bed 12 of the testing apparatus and which has slot-like apertures 17 therein having seals 18 therearound with which the planar elements 6 make sealing engagement.
Preferably the planar elements 6 each have a rebate 19 around the periphery thereof which engages the seal 18 of its corresponding aperture and the element 6 extends into its corresponding aperture 17 so that its lower surface is co-planar with the lower surface of the adaptor plate 15.
To connect the selected pins 9 of the planar elements 6 to the selected pins of the planar member 2, the interface is inverted from the position shown in the drawing and the housing 3 is removed. This leaves the planar elements 6 supported on the frame 5. The planar elements 6 are then each lifted in turn out of the plane of the planar member 1 and turned sufficiently to enable conductors 10 to be connected between selected pins of the planar member 2 and selected pins 9 of the planar element 6. Thus each conductor 10 need be of a length only sufficient to extend between the planar member 2 and the planar element 6. When all of the necessary connections have been made, the planar elements 6 are returned to the plane of the planar member 1 and the housing 3 replaced after which the interface is ready for use.
Claims (16)
1. An interface for establishing electrical contact between selected points on a printed circuit and selected electrical contacts of apparatus for testing the printed circuit, the interface comprising a pair of spaced planar members of electrically non-conductive material one of which has electrical contacts extending therethrough at selected positions thereon corresponding to selected points on the printed circuit and the other of which has electrical contacts extending therethrough at selected positions thereon corresponding to said selected electrical contacts of said testing apparatus, and electrical conductors connecting the corresponding electrical contacts of said planar members, at least one of said planar members comprising a pluralitt of planar elements each of which can be moved out of the plane of the planar member to enable said electrical conductors to be connected between the electrical contacts of the planar element and the corresponding electrical contacts of the other planar member.
2. An interface according to claim 1, wherein said planar elements are in the form of strips or slats which are arranged in parallel side-by-side relationship to form said at least one planar member.
3. An interface according to claim 1 or 2, wherein said planar elements are mounted in a frame.
4. An interface according to claim 3, wherein said frame is a square or rectangular frame having opposed frame portions between which end portions of said planar elements are received and which are connected together to retain the planar elements.
5. An interface according to claim 4, wherein one of said frame portions has locating pins or pegs thereon which engage corresponding apertures in said end portions of said planar elements.
6. An interface according to claim 4 or 5, wherein the other of said frame portions comprises the bottom wall of a box-like enclosure having side and end walls upstanding from said bottom wall, the top of the enclosure being closed by said other planar member.
7. An interface according to any one of the preceding claims, comprising support means between said planar members for preventing distortion or deflection of the planar member the electrical contacts of which make electrical contact with said selected electrical contacts of the testing apparatus.
8. An interface according to claim 7, wherein said support means comprises a peg or post located centrally of some or all of said planar elements.
9. An interface according to any one of the preceding claims, in combination with an adaptor plate having slotlike apertures therein corresponding to said planar elements.
10. A combination according to claim 9, wherein said planar elements each have a rebate around the periphery thereof of substantially the thickness of the adaptor plate and in which the adaptor plate is received, whereby that surface of each planar element which, when the interface is in use, is directed towards the electrical contacts of the testing apparatus is in the plane of the lower surface of the adaptor plate.
11. A combination according to claim 9 or 10, wherein the adaptor plate comprises sealing means for sealing each of said planar elements.
12. A combination according to claims 10 and 11, wherein said sealing means comprises an endless seal surrounding each said aperture in the adaptor plate and adapted to cooperate with the rebate of the corresponding planar element.
13. A combination according to any one of claims 9 to 12, wherein said adaptor plate is adapted when in use, to make sealing engagement with sealing means of the testing apparatus.
14. A method of forming an interface for use in testing a printed circuit comprising the steps of providing a pair of spaced planar members of electrically non-conductive material at least one of which comprises a plurality of planar elements each of which can be moved out of the plane of the planar member, inserting electrical contacts through each of said planar members at selected positions thereon, moving a said planar element out of the plane of the one planar member, connecting electrical conductors between the electrical contacts of the moved planar element and corresponding electrical contacts of the other planar member, and replacing the moved planar element in the plane of the one planar member.
15. An interface for establishing electrical contact between selected points on a printed circuit and selected contacts of apparatus for testing the printed circuit, the interface being substantially as herein described with reference to the accompanying drawings.
16. A method of forming an interface for use in testing a printed circuit, substantially as herein described with reference to the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB888810093A GB8810093D0 (en) | 1988-04-28 | 1988-04-28 | Interface for testing printed circuits |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8827791D0 GB8827791D0 (en) | 1988-12-29 |
| GB2217929A true GB2217929A (en) | 1989-11-01 |
Family
ID=10636043
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB888810093A Pending GB8810093D0 (en) | 1988-04-28 | 1988-04-28 | Interface for testing printed circuits |
| GB8827791A Withdrawn GB2217929A (en) | 1988-04-28 | 1988-11-28 | Modular interface for testing printed circuits |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB888810093A Pending GB8810093D0 (en) | 1988-04-28 | 1988-04-28 | Interface for testing printed circuits |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB8810093D0 (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2061630A (en) * | 1979-10-17 | 1981-05-13 | Standard Telephones Cables Ltd | Apparatus for testing printed circuit boards |
| GB2085673A (en) * | 1980-10-13 | 1982-04-28 | Riba Prueftechnik Gmbh | Printed circuit board testing device |
| GB2157507A (en) * | 1984-04-11 | 1985-10-23 | Standard Telephones Cables Ltd | Testing apparatus for printed circuit boards |
-
1988
- 1988-04-28 GB GB888810093A patent/GB8810093D0/en active Pending
- 1988-11-28 GB GB8827791A patent/GB2217929A/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2061630A (en) * | 1979-10-17 | 1981-05-13 | Standard Telephones Cables Ltd | Apparatus for testing printed circuit boards |
| GB2085673A (en) * | 1980-10-13 | 1982-04-28 | Riba Prueftechnik Gmbh | Printed circuit board testing device |
| GB2157507A (en) * | 1984-04-11 | 1985-10-23 | Standard Telephones Cables Ltd | Testing apparatus for printed circuit boards |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8827791D0 (en) | 1988-12-29 |
| GB8810093D0 (en) | 1988-06-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |