Model TR-7 Pneumatic Fixture System INSTRUCTION MANUAL

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1 Model TR-7 Pneumatic Fixture System INSTRUCTION MANUAL CheckSum, LLC th Street NE Arlington, WA Phone (360) FAX (360) Web Site:

2 P/N Revision Copyright CheckSum LLC, all rights reserved Printed in U.S.A. Specifications and operational characteristics of the System are subject to change. CheckSum, LLC cannot take responsibility for any direct or consequential damages arising from use of this manual or the related product.

3 Table of Contents Introduction System Overview 5 Specifications System Configuration 9 System Specifications 12 Installing the Fixture Press Orienting the Fixture Press 17 Interface Cable Connection (TR QC/TR QC) 17 Compressed Air Connection 17 Remote Control Connection 18 Power Connection 18 Installation of Top Plate Stiffener Kit 19 Installation Checkout 19 Customizing the Fixture Kit Positioning the UUT in the Fixture 24 Installing Guide Pins 24 Installing Spring Probes 25 Internal Wiring 29 Pressure Rods 32 Testing Operations Installing the Fixture into the Fixture Press 33 Connecting the Fixture to the Test Electronics 34 Installing the UUT in the Fixture 35 Applying Pressure and Performing the Test 35 Removing the Fixture from the Fixture Press 36 CheckSum Model TR-7 Manual - Page 1

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5 Limited Warranty CheckSum, LLC warrants its fixturing products to be free from defects in material and workmanship under normal use and service for the period of 90 days from date of original product shipment from CheckSum. This warranty extends only to the original purchaser and excludes products or parts that have been subject to misuse, neglect, accident, or abnormal conditions of operations. CheckSum, LLC reserves the right to replace the product in lieu of repair. If the failure has been caused, as determined by CheckSum, by misuse, neglect, accident, or abnormal conditions of operation, repairs will be invoiced at a nominal cost. In such case, an estimate will be submitted before the work is started, if requested. THE FOREGOING WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EX- PRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIED WAR- RANTY OF MERCHANTABILITY, FITNESS, OR ADEQUACY FOR ANY PAR- TICULAR PURPOSE OR USE. CHECKSUM, LLC SHALL NOT BE LIABLE FOR ANY SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, WHETHER IN CONTRACT, TORT, OR OTHERWISE. In the event of a failure of a product during the warranty period: 1. Contact CheckSum for a returned material authorization number (RMA). 2. Pack the product in its original packing material or suitable equivalent and return it postage-paid to CheckSum, LLC. Mark the package clearly with the RMA number. 3. CheckSum will repair the product and return it postage-paid. Repairs are typically completed within one working day of receipt. In the event that expedited repair is necessary, call CheckSum for information. In many cases a replacement product can be provided immediately. CheckSum Model TR-7 Manual - Page 3

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Introduction System Overview The CheckSum Model TR-7 Pneumatic Fixture System provides a means to connect your unit-under-test (UUT), such as a printed

7 Introduction System Overview The CheckSum Model TR-7 Pneumatic Fixture System provides a means to connect your unit-under-test (UUT), such as a printed circuit assembly, via a bed-of-nails to a CheckSum Test System. Figure 1 - Model TR QC Fixture Press (Loading Kit) CheckSum Model TR-7 Manual - Page 5

The Model TR-7 System includes a standard reusable fixture press that provides alignment and pressure for testing. For each UUT, a customized fixture is built using a low-cost replaceable fixture kit.

8 The Model TR-7 System includes a standard reusable fixture press that provides alignment and pressure for testing. For each UUT, a customized fixture is built using a low-cost replaceable fixture kit. The customized fixture is then installed in the fixture press when testing for the particular UUT is necessary. Changing the fixture kit only takes a few minutes for the TR , and under a minute for the TR QC and TR QC. The Model TR can accommodate UUTs of up to 1000 test points. The Model TR QC can accommodate UUTs of up to 3000 test points. Either tests UUTs up to approximately 13.2" by 16". Space for components above the circuit board is approximately 3.5". Figure 2 - Model TR Fixture (Ready to Test ) The CheckSum Model TR-7 Fixture System can be used with various CheckSum Test System electronics such as manufacturing defects analyzer (MDA) systems or functional test systems. CheckSum Model TR-7 Manual - Page 6

9 Model TR The Model TR can accommodate up to 1000 test points. It uses 50-pin ribbon cables to carry the stimulus and measurement signals from the test electronics in the System controller (PC) to 50-pin cable connectors on the back of the Model TR-7 Fixture Kit. Internal to the Fixture, custom wire-wrapped wiring carries the test signals from the rear connectors to the bottom of the spring probe receptacles. Installing a customized fixture kit into the press involves placing the probe-plate/pan assembly into the press, connecting the 50-pin test-point ribbon cables, then installing the polycarbonate pressure plate by putting it into position, then pressing it towards the rear to latch it into place. Model TR QC The Model TR QC is similar in capability to the Model TR , however it has a spring-probe fixture interface that allows you to change fixture kits without the need to connect and disconnect ribbon cables, thereby decreasing fixture-kit interchange time. Each interface block at the rear interface can accommodate up to 200 test points. The fixture press uses spring-probe blocks, and the fixture kit uses lower-cost target (wiring) blocks. Internal to the fixture, the wiring blocks have wire-wrap posts that are wired to the spring probe receptacles. Installing a customized fixture kit into the press involves placing the probe-plate/pan assembly into the press, then pressing it into place, which engages the interface probes. When it is seated, a plate automatically latches it into place. The top polycarbonate plate latches into place by putting it into position, then pressing it towards the rear to latch it into place. Model TR QC The Model TR QC can accommodate up to 3000 test points. It uses 200-point spring-probe transfer blocks to connect the stimulus and measurement signals from the test electronics in the System controller (PC) to the Model TR-7 Fixture Kit. Internal to the Fixture, custom wire-wrapped wiring carries the test signals from the rear transfer blocks to the bottom of the spring probe receptacles. Installing a customized fixture kit into the press involves placing the probe-plate/pan assembly into the press and installing the polycarbonate pressure plate by putting it into position, then pressing it towards the rear to latch it into place. CheckSum Model TR-7 Manual - Page 7

10 Testing To use the system for testing, the UUT is first placed onto the fixture. The UUT is typically positioned by means of guide pins that fit into tooling holes on the UUT. These provide accurate alignment with the spring probes. After the top cover is closed and latched, air pressure presses the UUT onto the spring probes. The UUT is pressed down onto the spring probes with pressure rods installed on the hinged top cover. Air pressure can be controlled manually with a switch on the press, or remotely by the test system with a digital input signal. Capabilities The standard Model TR , TR QC and TR QC provide a working travel of.50". This travel accommodates both single-sided and dual-sided probing, but not dual-level probing. The Model TR-7 Fixture Kit needs to be customized for the particular UUT, or family of UUTs, that it will be used with. This process involves drilling the fixture kit s probe plate for probes and guide pins, installing guide pins to align the UUT, installing spring probes/receptacles, doing internal wiring, and installing pressure rods. This customization process is described in this instruction manual. This manual describes the TR , TR QC, and TR QC Pneumatic Fixture Systems. CheckSum Model TR-7 Manual - Page 8

11 Specifications TR Configuration The Model TR Fixture Press includes the press, power cord, digital control cable, ground wire, and instruction manual. When building a customized test head, order: 1. A Model KIT1000 Fixture Kit which includes a probe plate and pan assembly, interface panel, clear polycarbonate pressure plate, and ten fixed-length pressure rods. 2. For each 50-points wired for the UUT, order one Model FIX-50P-WW 50-pin wire-wrap connector for connection to CheckSum Test System electronics. 3. For each probes, order a Model P-ROD pressure rod. Ten are included with each kit to accommodate UUTs of up to about 200 points. If tapered (pointed) pressure rods are necessary, order the P-ROD-T. CheckSum Model TR-7 Manual - Page 9

12 TR QC Configuration The Model TR QC Fixture Press includes the press, power cord, digital control cable, ground wire, and instruction manual: When initially ordering the Fixture Press, add one FIX-200P-RB Interface Block for each 200-points connected to the Test System. For example, if you have a 600-point system, order three FIX-200P-RB interface blocks with the Fixture Press. Other blocks may be necessary to support functional test or TestJet configurations. Contact CheckSum for the recommended configuration if the system has options beyond standard MDA test. When building a customized test head, order: 1. A KIT1000-QC fixture kit which includes a probe plate and pan assembly, interface panel, clear polycarbonate pressure plate, and ten fixed-length pressure rods. 2. For each 200-points wired on a particular fixture kit, order one Model FIX-200P- WB Wiring Block for wiring to UUT spring probes. 3. For each probes, order a Model P-ROD pressure rod. Ten are included with each kit to accommodate UUTs of up to about 200 points. If tapered (pointed) pressure rods are necessary, order the P-ROD-T. TR QC Configuration The Model TR QC Fixture Press includes the press, power cord, digital control cable, ground wire, and instruction manual: When initially ordering the Fixture Press, add one FIX-200P-RB Interface Block for each 200-points connected to the Test System. For example, if you have a 3000-point system, order fifteen FIX-200P-RB interface blocks with the Fixture Press. Other blocks may be necessary to support functional test or HP TestJet configurations. Contact CheckSum for the recommended configuration if the system has options beyond standard MDA test. When building a customized test head, order: 1. A Model KIT3000-QC which includes a probe plate and pan assembly, interface panel, clear polycarbonate pressure plate, and ten fixed-length pressure rods. 2. For each 200-points wired on a particular fixture kit, order one Model FIX-200P- WB Wiring Block for wiring to UUT spring probes. CheckSum Model TR-7 Manual - Page 10

13 3. For each probes, order a Model P-ROD pressure rod. Ten are included with each kit to accommodate UUTs of up to about 200 points. If tapered (pointed) pressure rods are necessary, order the P-ROD-T. CheckSum Model TR-7 Manual - Page 11

14 Specifications Fixture Press: Weight - TR Weight - TR QC Weight - TR QC Overall Dimensions Air Requirements Air Connection Electrical Connections Manual Control Remote Control ~ 110 lbs (~ 125 lb shipping wt.) ~ 120 lbs (~ 130 lb shipping wt.) ~ 145 lbs (~ 155 lb shipping wt.) 24" W x 24" D x 16" H (28" high with top open) PSI with 40 micron filtering. 100 PSI required with full probe loading. Standard quick-disconnect o 115/230V 50/60Hz Power o RCA jack for digital control o Banana jack for use with probe and/or wrist-strap Three-position switch for up, down, or remote control TTL high to open, TTL low to close. Internal 10 KΩ pull-up. Fixture Kits: Max. UUT Probe Area 13.2" x 16" Working Area Above UUT 3.325" normal (UUT PCB to top cover) Working Area Below Probe Plate 2.92" Probe Plate Top Cover 3 8" G-10 (FR-4) material 1 2" Clear polycarbonate material CheckSum Model TR-7 Manual - Page 12

15 Weight ~ 25 lbs Warranty: 90 days parts and labor limited warranty. CheckSum Model TR-7 Manual - Page 13

16 Ordering Information: Model Description TR Fixture Press, 1000-Point KIT1000 Fixture Kit, 1000-Point FIX-50P-WW 50-pin Interface Connector, 1000-Point P-ROD Pressure Rod (3.325") P-ROD-T Tapered Pressure Rod (3.325") FIX-SUPRT-T Top Plate Stiffener Kit for TR-7 FIX-SUPRT-BP Internal Fixture Kit Support Post (2.935") TR QC Fixture Press, 1000-Point Quick-Change FIX-200P-RB 200-Point Receiver Interface Block (with block, wiring, probes) KIT1000-QC Fixture Kit, 1000-Point Quick Change FIX-200P-WB 200-Point Fixture Kit Wiring Block P-ROD Pressure Rod (3.325") P-ROD-T Tapered Pressure Rod (3.325") FIX-SUPRT-T Top Plate Stiffener Kit for TR-7 FIX-SUPRT-BP Internal Fixture Kit Support Post (2.935") TR QC Fixture Press, 3000-Point KIT3000-QC Fixture Kit, 3000-Point FIX-200P-RB 200-Point Receiver Interface Block (with block, wiring, probes) FIX-200P-WB 200-Point Fixture Kit Wiring Block P-ROD Pressure Rod (3.325") P-ROD-T Tapered Pressure Rod (3.325") FIX-SUPRT-T Top Plate Stiffener Kit for TR-7 FIX-SUPRT-BP Internal Fixture Kit Support Post (2.935") FIX-PROBE mil Standard Spring Probe (specify head style) FIX-RECEP mil Wire-wrap Receptacle (socket) FIX-PROBE mil Standard Spring Probe (specify head style) FIX-RECEP mil Wire-wrap Receptacle (socket) FIX-PROBE mil Standard Spring Probe (specify head style) CheckSum Model TR-7 Manual - Page 14

17 FIX-RECEP mil Receptacle with wire FIX-TOOL-nnn 100-mil Receptacle Installation Tool (standard for TR-7 is FIX-TOOL-150) FIX-PIN-nnn Guide Pin (nnn is diameter in mil - standard is 122, 137, 156, or 183) CheckSum Model TR-7 Manual - Page 15

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19 Installing the Fixture Press Before use, it is necessary to install the Model TR-7 and connect it to its power and control resources. This chapter describes this process. Orienting the Fixture Press The fixture press is quite heavy, so you will not want to move it around on a regular basis. When it does need to be moved, ensure that at least two people do the moving (four is better), using the handles provided for this purpose on the side of the unit. In normal use, the fixture should be oriented on the left of the testing computer. This allows the cables and connections to be routed most neatly, and with easiest access to the controls. Interface Cable Connection (TR QC/TR QC) Connect the 50-pin ribbon cables from the back of the CheckSum test system to the cables at the back of the TR QC. These are labeled to eliminate confusion. If you have questions about how to make the connections, refer to (1) any customized system installation instructions that may have come with your system, (2) the Internal Wiring section of this manual for conventions used, or (3) call CheckSum for assistance. Compressed Air Connection Compressed air is supplied through the Air Supply Input connection on the right side panel. A standard quick-disconnect connection is provided for this purpose. If you would like to use another connection method, the nipple can be removed and you can connect an alternative fitting via a 3/8" threaded pipe connection on the fixture. Standard pressurized air can be used. For most applications, 70 PSI is adequate, although for full rated pressure, 100 PSI is required. This provides approximately 500 pounds UUT pressure. You should not connect supplies with more than 120 PSI to the fixture. A typical regulator with 40 micron filtering is suitable for air preparation. CheckSum Model TR-7 Manual - Page 17

20 Remote Control Connection If you will be controlling the fixture with the switch, no external remote connection is required. If you will be controlling it remotely, a TTL signal needs to be applied to the Digital Control Input RCA-style jack. This input is pulled high with an internal pull-up resistor. A logic low at this input causes pressure to be applied to the UUT. In order for the remote input to be active, the manual control switch on the side of the fixture needs to be in the Remote position. The latch on the front of the fixture press cover must be engaged before pressure can be applied. If you are purchasing the Model TR-7 as part of a test system from CheckSum, you will receive a remote control cable as part of the shipment. For TR-4 MDA Systems, this cable connects from the Aux I/O connector on the back of the controller (with a 15-pin D-Sub connector) to the Digital Control Input on the side of the fixture. For TR-8 MDA Systems or TR-10 MDA/Functional Test Systems, this cable connects from the RCA-type jack on the rear of the System Module (with an RCA-to-RCA cable) to the Digital Control Input on the side of the fixture. Power Connection You should connect power from a standard 110/120V 60-Hz source. It requires less than 0.25A at this voltage. Ensure that the arrows on the power-entry module that indicate V are pointing together. - CAUTION - Before removing the fuse block, ensure that the power cord has been removed from the power-entry module. If you will be using a V source, it is necessary to reconfigure the power supply. To do so, pull out the fuse block on the right side panel (just below the power cord). Replace the fuses with 0.125A fuses, and reinstall the fuse block. Orient the fuse block with the arrows pointing together that indicate V. Finally, ensure that the power switch is off (down, towards "0"), then install the power cord. CheckSum Model TR-7 Manual - Page 18

21 Installing the Top Plate Stiffener Kit For Model TR-7 test fixtures with greater than 500 test points, or concentrations of test points, it may be necessary to install a Top Plate Stiffener Kit (KIT-SUPRT-T) to reduce flex in the clear top cover of a fixture kit. If the top cover flexes appreciably, then the spring probe compression may not be adequate to make proper contact with the UUT. The Top Plate Stiffener Kit consists of (2) metal bars, (6) plastic pressure blocks, and (10) plastic thumb screws - (4) long and (6) short. To install the Top Plate Stiffener Kit, mount the stiffener assemblies to the lid of the TR-7 Fixture Press, perpendicular to the lid handle and in parallel with each other, with the long thumb screws. After installing the Top Plate Stiffener Kit on the TR-7 Fixture Press, and when installing the top cover of the fixture kit on the fixture press, you may need to loosen the thumb screws which hold the pressure blocks and adjust the pressure blocks so that they will not hit any obstacles on the top cover. Installation Checkout To ensure that the press is working properly, turn power on (the power switch should be up - toward "1"). On the TR QC, the platen will move up approximately one-third of an inch when power is turned on. Close the lid and ensure that the latch is fully engaged. Move the Fixture Control switch to the up and down positions and ensure that the platform moves up and down. When the platform is up, disengage the latch handle and ensure that the platform goes down. When it is re-engaged, the platform should go back up after a short delay. Finally, place the Fixture Control back to remote or down, then turn power off until the fixture is ready for use. CheckSum Model TR-7 Manual - Page 19

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Customizing the Fixture Kit Before using the Model TR-7 Fixture System, it is necessary to customize fixtures kits for each particular UUT, or family of UUTs, that you will be testing.

23 Customizing the Fixture Kit Before using the Model TR-7 Fixture System, it is necessary to customize fixtures kits for each particular UUT, or family of UUTs, that you will be testing. Figure 3 shows a KIT1000 with pressure rods installed and two Model FIX-50P-WW connectors. Figure 3 - Model KIT1000 This process can be performed by CheckSum, or local fixturing contractors that specialize in this type of work. CheckSum Model TR-7 Manual - Page 21

24 Alternatively, if you have equipment to do accurate drilling and wire-wrapping, customization can be done in-house. As an option, CheckSum can provide the necessary probes, accessories and special tools for building these fixtures. The steps involved in this process are covered in this chapter. Figure 4, on the following page, shows the Model KIT1000 layout for purposes of building the fixture. The probe plate dimensions are the same for the KIT1000, KIT1000-QC, and KIT3000-QC. CheckSum Model TR-7 Manual - Page 22

25 Figure 4 - Model KIT1000 Fixture Layout CheckSum Model TR-7 Manual - Page 23

26 Positioning the UUT in the Fixture There are several considerations when determining how to position the UUT in the test fixture: If you have potentiometers, jumpers, switches or adjustments that are made from the edge of the UUT, you should attempt to orient the UUT so that these are available from the sides rather than the front or back. For most right-handed people, it is easier from the right edge of the Fixture. Under normal circumstances, the UUT is centered on the fixture kit. However, you may wish to position it near an edge in some cases. For example: 1. You need easy access to the side of the assembly, or 2. You will be putting several UUTs on the same fixture. If your UUT has many probes, you should attempt to center it on the probe plate. This helps equalize the load on the operating mechanism for more precise actuation. Installing Guide Pins Guide pins are used to accurately position the UUT with respect to the spring probes. The guide pins go through tooling holes in the UUT. You should attempt to have at least two guide pins, positioned as far apart as possible, for every UUT. In most cases it is easiest for the operator to install and remove UUTs with only two guide pins. If the UUT is somewhat symmetrical and could be installed incorrectly, it is a good practice to install an additional, smaller guide pin in an unused non-symmetrical hole in the UUT. This can prevent the UUT from being installed incorrectly. Note If your UUT does not have tooling holes, you can use edge-guide brackets or guide pins. However, this is not ideal since alignment can be unreliable. The position of the guide pins is used as a reference for all of the spring probes, so they must be accurately placed. The guide pins should be approximately.003" smaller than the tooling holes in the UUT to allow easy placement of the UUT without binding, but still accurately positioning the UUT. The position and size of the tooling holes is normally CheckSum Model TR-7 Manual - Page 24

27 called out in the drill & trim drawing used for PCB fabrication or in the drill file for the UUT. There are four standard diameters of guide pins available from CheckSum. These can be reduced in size by a lathe if necessary. Since they are made of hardened stainless steel, use of a carbide cutting tool is recommended when turning them down to a different size. CheckSum also can provide a variety of non-standard sizes, contact the factory for size availability. The guide pins should not be installed until after the holes for the spring probes have been located and drilled. Otherwise they get in the way of the drilling process. When using CheckSum Model FIX-GPIN-nnn guide pins, you can use a #18 drill in the probe plate for each guide pin, then press the guide pin into place. Alternatively, you can use an 11/64" drill, slip the guide pin into place, then fasten it from the bottom with a #2-56 screw. Installing Spring Probes In typical manufacturing defects analyzers (MDAs), standard practice is to use one spring probe for each electrical network, even though that network might go to multiple components and pins. When four-terminal measurement capability is available, such as with the CheckSum Models TR-4 and TR-8, it is a good practice to install an extra pin on ground, each power supply, and any other low impedance components that need to be very accurately measured. This allows for external sense of these points. The MDA Instruction Manual has more details about how to choose test points, or you can call CheckSum to discuss this issue with respect to your specific testing needs. In general, though, there are no special requirements when wiring the test head for CheckSum MDA test electronics. Since the test points of CheckSum MDA Systems are all electrically equivalent, any point can be wired to any other point. The maximum current that can be provided by the test systems is in the low ma region, so large wires (greater than # 22-# 28) are not required. Also, no high frequency signals are present so the use of twisted pairs or coax wiring is not necessary. Note If you are wiring power to the UUT for power-on tests or other special requirements, you may need to increase the wire sizes beyond typical wirewrap sizes to accommodate current draws in excess of 100 ma. If you will be installing functional test modules in the fixture (e.g., the Model TR-6-2 Fixture Interface or the Model TR-4-SWO), these can be installed on the bottom of the CheckSum Model TR-7 Manual - Page 25

28 probe plate or on the bottom of the pan. If they are installed to the bottom of the pan, ensure that the securing screws are countersunk so that they do not protrude below the bottom of the sheet metal pan. The fixture is easier to work with if any accessory electronics such as this are attached to the bottom of the probe plate or connector plate. The first step is to assign test point numbers. If you are using CAD conversion to generate your test program, you can use the points assigned in this process. For manual test point assignment, it is easiest to first mark a schematic with sequential numbers showing the test points. This can be used to wire the fixture, then serves as a valuable aid to the programmers and technicians troubleshooting and repairing UUTs. Using this technique also allows the test program to be entered in parallel with fixture construction. Once you have electrically chosen the probe points, you can determine where to physically drill them. It is a good idea to drill all the PCB pad positions, but only install probes where necessary. This allows the flexibility to easily add or move probes as necessary to accommodate design changes or to correct for errors when first choosing probe placement. If you have a drill disk for your boards, but not an NC drill, it may be practical to have a facility with an NC drill (such as a PCB fabrication shop or CheckSum) do the drilling. If not, you can do the drilling yourself, either by drilling through an unloaded PCB or by using 1:1 filmwork of the PCB as a guide. For standard spring probe receptacles, such as those available from CheckSum, a #50 or 1.75mm drill is used. This yields a.068"/.070" hole. If you have any components on the bottom of the board, you can use a milling machine to create openings in the probe plate to provide clearance. The FR-4 (G-10) material, as used in the probe plate, is quite abrasive. Use of carbide drill bits and milling tools helps make the bits last longer. Once the probe board is drilled, you can install the spring probe receptacles (such as the CheckSum FIX-RECEP-100) from the top of the probe plate. To install them, use a small hammer in conjunction with a special tool (e.g., CheckSum FIX-TOOL-150) to tap the receptacles into place. The receptacles should be installed to the depth for proper compression when the UUT is pressed down. Typically, the proper compression length is two-thirds of the total travel for the probes. For example, if you are using a probe with.250" total travel (such as those provided by CheckSum), it should be compressed by about.167" when the UUT is installed. The CheckSum FIX-TOOL-150 installs the receptacles to be.150" from the top of the probe plate. When used with the standard length pressure rods, this provides the proper amount of travel for standard probing with.062"-thick PCBs. CheckSum Model TR-7 Manual - Page 26

29 This spacing also allows the probes, in most instances, to make adequate contact when directly touching the PCB where there are no leads. For optimum height when probing a bare PCB pad, you can install these receptacles at.200" height from the probe plate. Conversely, you can decrease the height of the receptacles if you have longer leads on the PCB. After the receptacles are in place, the spring probes are installed. These can be hand-pressed into the top of the receptacle with light pressure or with a plastic tool. Most probing can be accommodated by crown head style probes. Standard probes use about 5.5 oz. of spring force each, although higher force probes can be used if the probe count is relatively low and lower force probes (e.g., 3.5 oz) can be used in very high probe-count applications. The limiting factor on the total probe load (number of probes times the probe spring force) is the amount of pressure that the system needs to exert to press the UUT on the spring probes. If probe loading is excessive, it can also cause the fixture cover and probe plate to flex, causing improper operation. In high pin-count applications, you can install FIX-SUPRT-BP support posts in the fixture base. These can support the G-10 probe plate towards the middle of its span to minimize flexing. These are installed by drilling a.187 or.190 diameter hole in an unused area near the center of the fixture kit, and installing the post below the probe plate. If excessive top pressure plate flexing occurs, the polycarbonate plate can be reinforced with the FIX-SUPRT-T top plate support kit that can be installed on the fixture press to provide additional support to all top plates installed in the press. CheckSum Model TR-7 Manual - Page 27

30 Dimension A for Fixture UP is 3.7 inches (Fixture is engaged) Dimension A for Fixture DOWN is 4.2 inches (Fixture is disengaged) 0.5" CLEAR POLYCARBONATE TOP PLATE A inch Pressure Rod 0.313" 0.150" Receptacle Set Height 0.375" G-10 PROBE PLATE 0.062" UUT PCB Figure 5 - Fixture Profile (spring probe compressed) CheckSum Model TR-7 Manual - Page 28

31 Internal Wiring Once the receptacles are installed, the Fixture can be internally wired. This is performed by wire-wrapping from the bottom of the spring probe receptacles to the back panel connectors (on the TR ) or wiring blocks (on the TR QC and TR QC). Typically, a wire size of # 22-# 26 gauge is used for this purpose. For the TR , you will need enough 50-pin connectors to accommodate all of the test points wired for the assembly. These are available from CheckSum as part number FIX-50P-WW or available commercially from several connector manufacturers. They are installed into the connector interface plate on the fixture kit, so that the wire-wrap leads are inside the fixture. Install them so that points 1-50 are in the J1 position, in J2, and so on. Fixture kits are shipped from CheckSum with blank covers over the unused connector cutouts. These covers can be cut to be resized or are available in several sizes from CheckSum. The connector pin numbers are shown on the interface panel of the fixture. The pin-out for a typical connector is shown in Figure 6 below Figure 6 - TR Connector Numbering Convention (shown from top front of the Fixture Kit) For the Model TR QC and TR QC, you will need enough 200-point wiring blocks to accommodate all of the test points wired for the assembly. These are available from CheckSum as part number FIX-200P-WB. They are installed into the interface plate on the fixture kit, so that the wire-wrap leads are inside the fixture. Install them so that points are in the A position, in B, and so on. CheckSum Model TR-7 Manual - Page 29

32 Figure 7 shows the block installation convention used by CheckSum for the Model TR QC. L M N P R F G H J K A B C D E Figure 7 - KIT3000-QC Wiring Block Installation Convention (shown from top front of the Fixture Kit) Test-points can be wired starting at block A (1-200), B, C, D, F, G, H, J, L, M, N, P, R, K, and ending at block E. In most installations, other options may be installed in the test system. The convention used by CheckSum is shown in Figure 9. Figure 8 shows the block installation convention used by CheckSum for the Model TR QC. A B C D E Figure 8 - TR QC Wiring Block Installation Convention (shown from top front of the Fixture Kit) Test-points can be wired starting at block A (1-200) and ending at block E (points ). In most installations other options may be installed in the test system. The CheckSum Model TR-7 Manual - Page 30

33 convention used by CheckSum is shown in Figure 9. Module Default Block Connection TR QC TR QC FUNC-2 E151 - E200 E151 - E200 TR-6-1 #1 E101 - E150 E101 - E150 PWR-2 E51 - E100 E51 - E100 DIG #1 K101 - K150 D151 - D200 DIG #2 K151 - K200 D151 - D200 SMT #1 E1 - E50 E1 - E50 SMT #2 E101 - E150 E101 - E150 Figure 9 - TR QC/TR QC Accessory Block Installation Convention Fixture kits are shipped from CheckSum with blank covers over the unused connector cutouts. These covers can be cut to be resized or are available in several sizes from CheckSum. The connector pin numbers are shown on the interface panel of the fixture. The pin-out for a typical connector is shown in Figure 10 as follows Figure 10 - KIT1000-QC/KIT3000-QC Connector Numbering Convention (shown from top front of the Fixture Kit) CheckSum Model TR-7 Manual - Page 31

34 Pressure Rods Once the UUT has been drilled and wired, the pressure rods that press the UUT down onto the spring probes are installed. The fixed-length pressure rods are installed by drilling 3/16" holes in the top polycarbonate cover, then installing the pressure rod with a #10 screw (provided). You should install a minimum of four to six pressure rods. The more probes that you have and the larger the UUT, the more pressure rods you will need. For each 100 probes that are installed, the upward force on the UUT will be about 33 lbs. Typically, one rod is installed for about each probes, depending on the board layout. If the UUT has any switches or adjustments which require access from above, the access holes should be drilled or milled out at this time. In order to maintain the strength of the top cover for high point-count assemblies, the access holes should be no larger than necessary for access. Note In order to ensure proper alignment when drilling or milling the cover plate, there are accurate matching alignment holes near the center edge of the Fixture probe plate and top cover. The location of these.250" diameter holes are shown in Figure 4. CheckSum Model TR-7 Manual - Page 32

35 Testing Operations with the Model TR-7 After the Model TR-7 fixture has been customized, but before it is used, it must be installed in the fixture press, connected to the Test System and the UUT must be installed in it. This section describes how to perform these operations. Installing the Fixture into the Fixture Press To install the fixture into the press, there are two operations: TR First, the probe plate/pan are placed into the press. This is done by simply placing the fixture into the press and allowing it to self-align with the guide pins in the base. 2. The top pressure plate is installed into the fixture. This is done by aligning it with the four latches in the top plate of the fixture press, then sliding it back until it clicks into place. TR QC 1. First, the probe plate/pan are placed into the press. This is done by placing the fixture kit interface plate pivot posts into the holders on the side rails, then pressing the front of the kit down until it latches into place. 2. The top pressure plate is installed into the fixture. This is done by aligning it with the four latches in the top plate of the fixture press, then sliding it back until it clicks into place. TR QC - Caution - When using the TR QC, ensure that fingers are not placed in the transfer probe area at the rear of the fixture press. 1. Turn off power to the fixture press. This allows the fixture press to go to a load/unload position. Rotate the side handle up to lift the rear probe interface block assembly. Then, the probe plate/pan are placed into the press. This is done by simply placing the fixture into the press and allowing it to self-align with the CheckSum Model TR-7 Manual - Page 33

36 guide pins in the base. Then rotate the side handle down to lock down the rear probe interface block assembly. Next, turn power on to the fixture press. This allows the fixture to move from the load/unload position to the neutral position. 2. The pressure plate is installed into the fixture. This is done by aligning it with the four latches in the top plate of the fixture press, then sliding it back until it clicks into place. Connecting the Fixture to the Test Electronics This operation is necessary only for the TR The ribbon cables from the test electronics connect directly to the connector plate of the Model TR-7 fixture kit. Each connector is labeled to show which test point cable should be connected. J1 is connected to points 1-50, J2 to , and so on. Note In order to protect the UUT and Test System from ESD (electrostatic discharge), it is advisable to have the operator wear a wrist strap. Typical ESD wrist-straps with banana plug connectors can be directly connected to the fixture s side panel banana jack. CheckSum Model TR-7 Manual - Page 34

37 Installing the UUT in the Fixture To install the UUT into the completed test fixture, first open the top cover. To do so, grasp the top latch handle in the front and press it back. Once it is unlatched, the top opens with assist from the struts. The UUT is then installed over the guide pins. Once the UUT is in place, the top cover is pressed down until the latch engages, which holds the top cover (and UUT) in place. Note CheckSum provides fixtures and fixture kits for our standard 0.50"-travel version. The TR QC and TR QC Fixture presses with 0.50"-travel have a third guide-pin (on the right side-rail, 4.25" below). Fixture kits that are designed for 0.50" travel have a clearance hole for this guide pin. Applying Pressure and Performing the Test Note Before applying pressure to the UUT, check to ensure that the pressure rods are not going to make contact with the UUT in the wrong places. If this is the case and power is supplied, the press has adequate force to seriously damage the fixture and/or the UUT. If you are manually running the fixture, move the Fixture Control switch to the up position. The fixture will not engage if the latch handle is not closed. If the fixture press is under remote control, ensure that the latch is engaged and the Fixture Control switch is in the Remote position. CheckSum Model TR-7 Manual - Page 35

38 After the test, ensure that the pressure is removed (either remotely or by moving the Fixture Control to the down position), then unlatch the fixture lid and remove the UUT. Removing the Fixture from the Fixture Press Once you are done testing a type of assembly and ready to change to a new type, it is necessary to remove the fixture kit from the press. To do so: 1. TR : Remove the ribbon cables from the back of the test fixture. TR QC: Holding down the front of the fixture kit, pull the latch lever towards you until the fixture releases. TR QC: Turn power off to the fixture press. Rotate the side handle to the fully-up position. 2. Remove the probe plate/pan assembly from the press. This is done by simply lifting it out using the two handles provided. 3. Use the fixture storage kit or install the four storage/shipping posts into the probe plate by threading them into the 1/4"-20 tapped holes near the corners of the probe plate. 4. Remove the top pressure plate by pulling it towards you until it unlatches, then let it down until it is free from the top latches so it can be completely removed. 5. Place the pressure plate on the fixture storage kit or secure the pressure plate to the probe plate by screwing 1/4"-20 screws through the pressure plate holes and into the storage/shipping posts on the pan assembly. By using this storage method, the spring probes and pressure rods are protected from damage. CheckSum Model TR-7 Manual - Page 36