Module 08 Fixture I

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HP3070 Tester

Transcript of Module 08 Fixture I

Agilent 3070 User Fundamentals

Module 8: Fixture ITable of ContentsThe Test Development Process ............................................................................................... 2 The Test Fixture ...................................................................................................................... 3 The Test Probe................................................................................................................. 3 The Personality Pin.......................................................................................................... 4 The connection process.................................................................................................... 4 Simplate Fixture (above left) ........................................................................................... 5 Simplate Express Fixture (above right) ........................................................................... 5 Issues ....................................................................................................................................... 6 Fixture Electronics........................................................................................................... 7 TestJet Probe ........................................................................................................................... 8 Agilent IPG Test Consultant & the Fixture ........................................................................... 10 The Individual Parts of the Fixture Generation Software.............................................. 11 Board Placement ............................................................................................................ 11 Probe Select ................................................................................................................... 13 Allocating Power Supply resources............................................................................... 15 Module Pin Assignment ........................................................................................................ 17 Module Pin Assignments Inputs & Outputs................................................................. 18 Fixture Tooling...................................................................................................................... 19 Extra Personality Pins.................................................................................................... 20 Fixture Tooling Outputs ................................................................................................ 21 The Files for the Fixture Builder ........................................................................................... 22 Bank Row Column ................................................................................................................ 24 Fixture Verification ............................................................................................................... 25 Running Test Consultant Multiple times............................................................................... 28 Re-running Fixturing Software BEFORE a fixture is built ........................................... 28 Rerunning Fixturing Software AFTER a fixture is built ............................................... 29 Examine the fixture/details file .................................................................................. 30 Glossary................................................................................................................................. 31 Appendix ............................................................................................................................... 32 fixture/fixture.o details....................................................................................................... 32 fixture/summary - after Board Placement .................................................................. 33 fixture/details.............................................................................................................. 33 fixture/summary - after Probe Select ......................................................................... 33 fixture/fixture.o output - after Module Pin Assignment ............................ 34

Fixture I 8 - 1

Agilent Technologies

Test Development FlowchartProcess1 2

Filesboard

ToolsCAMCAD Translator BT-BASIC Board Consultant Part Description Editor Digital Setup Editor IPG Test Consultant PushButton Debug

Translate CAD Describe board & system

board_xy config Custom libraries

3 4 5 6

Generate Test & Fixture files Build & Verify test Fixture Turn-On / Debug all Tests Release to Production & Long Term Support

testability.rpt Fixture Files Individual Test Files testplan

ECO

Generates

Modify1

3070 User Fundamentals Module 8: Fixturing

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The Test Development ProcessDuring previous modules, you: Created the config file, Translated the CAD into a board description, Completed the board description using Agilents Board Consultant, Part Description Editor, Digital Setup Editor, Generated and evaluated the testability.rpt, Generated the fixture and test files using Agilent IPG Test Consultant. Regenerated and reevaluated the testability.rpt

Now, the development continues with an overview of fixture types, the fixture files, the parts of the fixture and fixture verification. Later in the class, the Agilent Fixture Consultant will be examined. For now, it will be skipped so you can concentrate on a general overview of the entire fixture process.

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Agilent 3070 User Fundamentals

The FixturesTooling Pin Vacuum Gasket

Personality Pins

Simplate ExpressPins

Alignment Plate

SimplateBoard Support Plate Probe Plate3070 User Fundamentals Module 8: Fixturing

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The Test FixtureThe goal of fixturing is to connect the testhead resources to the PC board with the minimum of impedance, reactance or inconvenience. There are two basic fixture types: Simplate Simplate Express

During this class the focus is on the Simplate Express or short wire fixture. The Simplate or long-wire fixture is also described. Two other fixture types are not described as they are only seldom used. The Express Cassette fixture was used in the EFS Board Handler. The EFS is no longer in production, having been replaced by more modern automated board handling equipment. The XG-50 fixture was used to propagate higher frequency signals. As with the EFS, more modern test techniques have all but made this fixture obsolete.

The Test ProbeThe test probe is a four part assembly. The socket is press-fit into the Probe Plate. The height of the socket is carefully controlled. This ensures the probe can compress more than the fixture, to make sure the probe is not damaged during test. The tail of the socket is a wire wrap post.

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Agilent Technologies The test probe assembly is inserted into the socket during the fixture build process. This probe will last many months but can be replaced easily. The probe assembly consists of three parts. A sleeve, a spring and the probe itself. The spring is mounted inside the sleeve. The probe inserts into the sleeve and attaches to the spring. The probe assembly is then inserted into the socket. Together these are generically referred to as the probe even though it is really the probe assembly and socket. During test, the probe tip lightly scratches the surface of the solder or copper when the fixture compresses. This scratch is usually sufficient to clear away oxidation or surface contamination thus ensuring good electrical contact during test. It is usually not enough to pit the surface. There are dozens of different point types for fixture probes. As with the different probe point types, there are a number of different spring forces, probe lengths, probe diameters, etc. Most people try several variations and qualify one or two types of probes for their applications and environments. NOTE: Caution should be used when cleaning the probes. Any solvent that penetrates between the probe and the spring/sleeve assembly will dry out the lubricants within the sleeve and the probe will fail prematurely.

The Personality PinThe Personality Pin (or P-Pin for short) is used to connect to the testhead resource. It has a plastic top that is press fit into the bottom of the Probe Plate at specific coordinates (defined by the fixture software). The post is simply a wire wrap pin that will hold at least three wires.

The connection process The test Operator loads the board to test onto the fixture. Tooling Pins mounted in the Probe Plate, but extend through the Support Plate ensure a quality alignment. The board rests on a combination of vacuum gaskets around the parameter of the board and spacers or pads scattered evenly around the interior of the board. The system asserts vacuum to the fixture. This creates a vacuum chamber between the printed circuit board and the Probe Plate. Vacuum holds the printed circuit board to the Support Plate. Springs holding the Support Plate to the Probe Plate compress pulling it and the board toward the Probe Plate. The test probes are also spring loaded and they compress as the board pushes them toward the Probe Plate. The board travels to a physical stop. The probes, resisting that travel embed their points into the solder on the test points of the board.

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Agilent 3070 User Fundamentals The 3070 generates a signal. That signal is propagated from its source on a Pin Card, to the fixtures test Pin. Through the fixture wiring to the Probe. Through the probe to the test point on the printed circuit board. The signal travels through pa