How To Help The Gap Between Design & Production Test Bert Horner The Test Connection, Inc. Rev 2.2 2013 PCB Carolina Test Methodologies Rev 1.2 10/30/09 Test (ATE) VS. Inspection (AOI or AXI) •Test is the means by which the presence, quality, or genuineness of anything is determined; a means of trial. •Inspection is official viewing or examination. As You Can See….Test & Inspection Are Different What Are The Most Common Faults On Boards? Manufacturing Testing Electrical Test ATE Comes In Different Flavors…. In-Circuit Test ICT Flying Probe Test Functional Test JTAG Boundary Scan IEEE 1149.1 Boundary Scan Test AKA: JTAG - Joint Test Action Group AKA: IEEE 1149.1 What Is It? A standard specifying how to control and monitor the pins of compliant devices on a printed circuit board. Figure 1 Figure 2 JTAG (1149.1) Advantages • Quick Test Development Time. • Ability To Do In-System Programming (ISP) Of Complex Devices. • Using BSDL Tests That Were Already Developed By Chip Mfg’ers. JTAG (1149.1) Disadvantages • Designers Need To Be Aware Of JTAG Design Rules. (VERY IMPORTANT) • Custom Cable Or Interface. • BSDL Tests Need To Chip Mfg’ers. • *Only Works With Digital Devices…No Analog * National Semiconductor Does Have One Analog Devices That Is 1149.4, But Not Being Used By Anyone. In-Circuit Test (ICT) AKA ‘Bed Of Nails’ Two Largest ICT Mfg’ers: Agilent 3070 (I3070) & Teradyne (Formerly GenRad) 228X or TestStation Digitaltest MTS300 ICT or Bed Of Nails Use A Test Fixture To Mate Up To Common Interface. In-Circuit Test Fixtures Not Ever Fixture Is Meant For Every Test System ICT What To Look For… -Probing -Chip Interconnectivity Test Pads Test Vias Agilent Technologies Bead Probe Technology (See Handout) ICT Advantages • Automated Tester. • Lower Level Operators Needed. • Faster Test Times. • Good Diagnostics. ICT Disadvantages • Expensive Tester. • Cost For NRE Set Up. • Needs a Fixture or Bed Of Nails Interface. • Fixture Needs Maintenance. Flying Probe Test AKA ‘Fixtureless Test’ Want To See Them Move? Flying Probe Advantages • Minimalize Exposure - NRE Set Up. • Faster Time To Production Ready Testing. • Limited Or No Fixture. • More DFT Lenient. Flying Probe Disadvantages • Slower Test Time. • Electromechanical System (Regular Maintenance Needed). • With Age Of Systems, Separation In Technology. • Systems Costs. Functional Test AKA System Test or ‘Rack & Stack Testing’ PXI Considerations: 1) Documentation 2) Technology Used 3) Sustainability 4) Repeatability 5) Diagnostics Bench top Or Custom VXI Examples of BAD Functional Test Figure 1 Figure 3 Figure 2 Can you guess why? Functional Test Advantages •Parametric Testing. •Operations/Functions Validated. •Able To Be Used For Field Returns. •PC Based Instruments. Functional Disadvantages •Manual Test Generation. •Manual Test Procedures – Documentation. •Proprietary Product Knowledge. •Higher Level Operators. Methodology Conclusion Production test does add value to your product. Why? • Reduces expensive field returns. •Diagnostics for production related errors…..reduces troubleshooting time. •Feeds process related information to production. CAD vs. GERBERS (From A Test Engineering Point Of View) Rev 1.2 03/20 CAD vs. GERBER Is There A Winner? CAD vs. GERBER Why Is GERBER Not Good Enough? Raw GERBER data is devoid of most intelligent information used in manufacturing test such as referenced designators, device body center (x/y), device rotation and pin numbers. “...GERBERS are a picture of the CAD…” Olaf Rohrbacher of Digitaltest GmbH CAD vs. GERBER What & Why Is This Needed For Test? •Device Body Center (x/y): Probe placement for either flying or fixed probes. Needed for machining of fixture. (A) •Device Rotation: Probe placement for either flying or fixed probes. (B) •Referenced Designators: Failure information needs to be called out to the lowest level (i.e. net and component). (A) •Pin Numbers: Failure information needs to be called out to the lowest level (i.e. net, component and pin). (B) CAD vs. GERBER What information is in the ASCII CAD? 1. 2. 3. 4. 5. 6. 7. Location Reference. X & Y Coordinates. Theta (Part Rotation). Part Number (Reference to BOM). Package Style. PCB Mount Side (Top or Bottom). Component Technology (SMT or PTH). ASCII CAD is not important…It’s VERY Important. Looks The Same? Gerber CAD Closer Look…..I See Differences Gerber CAD CAD vs. GERBER What does GERBER by us? GERBER files is used by fixture vendor to set “push down fingers” or “golf tees” to get the board in place. They also us this information for vectorless testing. The GERBERS are used to make the capacitive plate of TestJet, Opens Xpress, and Opens Check. TestJet or VTEP for Agilent Opens Xpress or FrameSCAN for Teradyne (GenRad) Opens Check for Digitaltest Old Boards With No CAD….Now What? No CAD, Only GERBERS…. There are tools that can be used that used, but there is a cost of time and money. CAM350 and GraphiCode. This process is called "Reverse Engineering". C-LINK doesn't contain a software module which does this - because we advise our customers to use native CAD data as input because this faster. Translating CAD to a manufacturing test format can be minutes verses 1-2 days using GERBERS. If working with a larger board (1500 nets) that has a mix of THT and SMT, it can be even more like 15 minutes compared to 5 Days. Because reverse engineering is a manual and time consuming process, it’s not always error free. CAD vs. GERBER Who is the winner? BOTH Are…..We need both CAD & GERBER. “... I always ask for both, we need them…” Joe Folsom of The Test Connection More Practices for Gaining Access and/or Cost Cutting of Production Test Rev. 1,1 Fixturing Should be Kept To Probing to One Side. Sample is Agilent 3070 Sometimes We Need to Probe Both Sides…Clamshell Items to Consider: 1) Added Cost. 2) Time To Build. 3) Flipping the UUT? 4) Probing Tolerances. 5) Technology Used. When Fixturing, Knowing the Limitations The Lower Limits are Safer Limits. NOT meant for the entire board. Bottom side. Make The Tester Successful….  Pick a test solution that can be supported.  Picking a interface that is “servable”.  Have back up plan – 2nd or 3rd Vendor.  Document. Things to Think About Test, Inspection or Both? What Faults Keep You Awake? Types of Testers? How to Interface? Manufacturing Match Up? Types of Data? CAD Format? Where to Probe? Size of Probes? Design For Test (DFT) Notes: http://www.ttci.info/DFTRules.html Questions? Thank you for your time. Bert Horner [email protected] (410) 205-7300