Universal fixtureless test equipment

• US 5,781,021 A
• Filed: 10/30/1996
• Issued: 07/14/1998
• Est. Priority Date: 01/11/1994
• Status: Expired due to Fees

• Current Assignee: Key Solutions Incorporated
• Original Assignee: Key Solutions Incorporated
• Inventors: Ilani, Avner
• Primary Examiner(s): Karlsen, Ernest F.
• Assistant Examiner(s): Phung, Anh
• Application Number:
  US08/740,514
• Time in Patent Office: 622 Days
• Field of Search: 324/754, 324/765, 324/755, 324/758, 324/761
• US Class Current: 324/755.08
• CPC Class Codes: G01R 1/07385 using switching of signals between probe tips and test bed, i.e. the standard contact matrix which in its turn connects to the tester
• CPC Class Codes: G01R 31/2808 Holding, conveying or contacting devices, e.g. test adapters, edge connectors, extender boards probe, multiprobe, probe manipulator or probe fixture G01R1/067

Abstract

A universal, fixtureless automatic test equipment is provided, capable of accessing opposite surfaces of any workpiece, simultaneously, for functionality testing. The workpiece can be freely placed anywhere on the test area, regardless of orientation, without the need for pre-test registration, alignment, or any kind of securing means. The test area of a universal fixtureless automatic test equipment, according to the teachings of the present invention, is made up of Independent Test Modules (ITMs). A test area may be configured from any number of ITMs, as desired. The ITMs can be individually selected for testing various functions of a respective section of a workpiece under test, and for independent electrical functioning. A typical ITM is made up of a plurality of semiconductor dies. Dies are similarly structured with matrices of selectable memorized bidirectional switching cells. Each switching cell is connected to a terminal-pad on the surface of the die. The terminal-pads extend to a test mattress of highly dense, compressible micronic bumps by means of a Adapter/Pitch Translator. These bumps function as independent test electrodes and are dimensioned to provide two positive features: to guarantee that each tested element on a workpiece corresponds with at least two of the test electrodes, and that the test electrodes are dimensioned to prevent shortages between adjacent pairs of tested elements.

Claims

1. A test equipment including at least one test area for testing the functionality of a workpiece placed in an arbitrary position and orientation on the test area, for contacting conductive elements of said workpiece, regardless of pitch and configurations of the conductive elements of the workpiece, the test area comprising:

(a) a base plate;

(b) at least one test module mounted on said base plate, said test module having compressible means on a surface facing said base plate, such that when mounting said test module on said test plate, said compressible means lies between said test module and said base plate, said test module including;

(1) at least one semiconductor die, said die including integrated electronic circuitry including an array of selectable memorized switching cells, each said switching cell terminated by a conductive terminal pad, said conductive terminal pad functioning as an input/output contact, said terminal pads matrixed on a surface of said semiconductor die, such die having said electronic circuitry integrated in the remainder area unoccupied by said pads, said terminal pads having bumps of conductive material at ends of said terminal pads;

(2) a plurality of conductors for use as test electrodes, arrayed in a parallel manner such as to produce a 3-dimensional multi-electrode adapter/pitch translator, having first and second conductive cross-section surfaces, first ends of said electrodes on first surface of said adapter/pitch translator being matrixed and pitched to correspond to said bumped terminal pads of said semiconductor die, second ends of said electrodes on said second surface of said adapter/pitch translator being pitched and matrixed such as to guarantee that each conductive element of the workpiece will be contacted by at least one test electrode for any arbitrary positioning angle of the workpiece on the test area; and

,

(3) said bumped semiconductor die, being flipped and permanently mounted on a corresponding conductive cross-section surface of said adapter/pitch translator such that each bumped pad of said die is in direct contact with a corresponding test electrode of said adapter/pitch translator,

whereby each test electrode is connected to a selectable memorized switching cell of the semiconductor die.

2. The test equipment of claim 1, said second ends of said test electrodes facing said workpiece further comprising bumps of compressible conductive polymer material.

3. The test equipment of claim 1, further comprising a compressible non-conductive cushion filled with micronic conductive particles, said cushion placed on said second cross section surface of said adapter/pitch translator facing the workpiece,

said cushion having bumps on said second surface facing the workpiece, said bumps having density and pitch corresponding to density and pitch of said second cross section surface of adapter/pitch translator facing said cushion, such that each test electrode is connected to a respective conductive test bump by a few conductive particles of said cushion,

compressibility of said cushion assisting said test bumps to gently tolerate fine variations in heights of said contacted conductive elements on the workpiece.

4. The test equipment of claim 1, wherein said bumps of the test area touching the workpiece are formed by precise printing process.

5. The test equipment of claim 1, wherein said bumps of the test area touching the workpiece are formed by laser etching process.

6. The test equipment of claim 1, wherein density and pitch of test electrodes at surface facing the workpiece is scaled such as to provide a continuous uniform mattress of test electrodes through design of new adapter/pitch translator'"'"'s, thereby providing for universal usage in accordance with technological advancements needs.

7. The test equipment of claim 1, said test module comprising a plurality of semiconductor dies, each semiconductor die having a controlled powering device for autonomous ON/OFF activation and functioning for test, such that different combinations of semiconductor dies belonging to different test modules can be selected according to test needs, leaving the not relevant remaining test modules unactivated.

8. The test equipment of claim 1, said test module further comprising a shielding cover bracketing said plurality of semiconductor dies mounted on said adapter/pitch translator, outer surface of said shielding cover facing said base plate having said compressible means between the outer surface of said cover and said base plate.

9. A test equipment as in claim 1, the test area comprising a plurality of said test modules mounted on said base plate having compressible means between each said test module and said base plate, such that when pressing said test plate with said modules toward the workpiece, said compressible means of each said test module are individually compressed, allowing each said module to accommodate variations in height of each corresponding section of the workpiece.

10. The test equipment as in claim 1, further comprising a second congruent test area, substantially parallel to the test area, the test equipment for simultaneous functionality testing of both surfaces of a workpiece placed in an arbitrary position and orientation with respect to the test area and said second test area, for contacting the conductive elements of the workpiece, regardless of pitch and configurations of the conductive elements of the workpiece.

11. The test equipment of claim 10, wherein said test electrodes have a density such as to guarantee that each conductive element on both surfaces of the workpiece will be contacted for any arbitrary position and orientation of the workpiece on the test area,

thereby eliminating the need for setup preparations such as modification of the test area, fixturing, mechanical adjustments, alignment, and registration, of the workpiece.

12. A test equipment as in claim 1, wherein said test electrodes of said adapter/pitch translator are pitched and matrixed such as to guarantee that each conductive element of the workpiece will be contacted by at least two said test electrodes for any arbitrary position and orientation of the workpiece on the test area.

13. A test equipment as in claim 12, guaranteeing two said test electrodes contacting each conductive element on the workpiece, further comprising guaranteeing a third test electrode contacting conductive element, whereby enabling precise measurements of impedance and resistance of that section of said element between said at least two said electrodes and said third test electrode.

14. A test equipment as in claim 12, wherein, for a workpiece including a floating conductive element on the workpiece, said at least two said electrodes contact said floating conductive element on the workpiece, whereby enabling location verification of said floating conductive element, said location verification including closing a test circuit connected between said at two said electrodes.

15. A test equipment as in claim 12, further comprising an electrical test circuit for connection to said at least two said test electrodes contacting said conductive element on the workpiece, whereby enabling verification of contact reliability, thereby enabling elimination of false detection of open-circuited elements.

16. The test equipment of claim 1, the workpiece including multi-element nets having multiple conductive elements, wherein

said switching cells are structured such as to enable a test signal to enter through one conductive element of a multi-element net on the workpiece, as input to the workpiece,

said test signal conducted simultaneously through remaining conductive elements of the net as outputs, to a multi-line data-out-buss leading to a central control unit,

thereby enabling a one-shot reporting of continuity status between said input conductive element of said net as input, and said remaining conductive elements of the net as parallel outputs.

17. A test equipment as in claim 1, the workpiece including multi-element nets having multiple conductive elements, wherein

said switching cells are structured such to enable simultaneously testing more than one multi-element net,

including a test signal entering simultaneously through different conductive elements of different nets on the workpiece, as inputs,

being conducted out through the remaining conductive elements of the respective net, as independent outputs, to a multi-line data-out-buss leading to a central control unit,

thereby enabling a one-shot reporting of continuity status between each of said input conductive elements of said nets and the respective remaining conductive elements of said nets as independent groups of parallel outputs.

18. A test equipment as in claim 1, said switching cells structured such to enable simultaneous testing multi-duplicates of an electronic circuit printed in step-and-repeat manner on the workpiece, wherein,

for each said duplicate electronic circuit, a test signal entering simultaneously through different conductive elements of different nets on the workpiece as inputs, can be conducted through the remaining conductive elements of the respective net, as independent outputs, to a multi-line data-out-buss leading to a central control unit,

thereby enabling a one-shot reporting of continuity status between each of the input conductive elements of said nets and the respective remaining conductive elements of said nets as independent groups of parallel outputs.

19. A test equipment as in claim 1, the test module further comprising the capability of probing conductive filaments extending from a package of a component mounted on the workpiece,

thereby enabling in-circuit testing of the functionality of said component.

20. A test equipment as in claim 1, said semiconductor die further comprising an in-circuit ON/OFF powering device.

21. A test equipment as in claim 1, wherein said adapter/pitch translator includes metallic sheets shaped as comb-teeth, said metallic sheets insulated by non-conductive material.