Automated Accelerated Life Testing Data Collection on Thousands of DC Passive Parts

Transcription

1 Automated Accelerated Life Testing Data Collection on Thousands of DC Passive Parts Jeremy Young Parts Materials and Processes Department Electronics and Sensors Division The Aerospace Corporation Microelectronics Reliability and Qualification Workshop 9 February The Aerospace Corporation

2 Background The purpose of this study sprang from a lack of independent data on Multi-Layer Ceramic Capacitors (MLCC) using base metal electrodes (BME) regarding their failure modes, if unique. The goal was to collect large amounts of stress-to-failure data on BME MLCCs trying to eventually map out failure modes. The entire investigation uses all tools available at Aerospace, including Focused Ion Beam (FIB) cross-section, Scanning Electron Microscopy (SEM), Tunneling Electron Microscopy (TEM) & Energy Dispersive X-ray Spectroscopy (EDS) for construction analysis, optical microscopy, acoustic microscopy, x-ray inspection, as well as electrical characterization and simulated parts screening. This presentation describes the electrical test setup created for electrical/thermal accelerated stress testing. 2

3 Electrical Stress Testing Goals Strong desire to stress large numbers of parts at once. For thousands of Devices Under Test (DUTs), an automated test system with minimal human effort was needed Automated system aims to be test plans translated into code. Strong desire to keep costs down. Large automated test systems tend to become expensive very quickly. Strong desire for test system flexibility. Wide variety of MLCC BME parts creates flexibility need. MLCCs are not the only surface mount device that might be used. Desire to collect time-resolution data on the following parameters: DUT Leakage current DUT Capacitance DUT Temperature 3

4 Basic Measurement Circuit Measurement Points Switch DUT Ballast Resistor DUT Rail Ballast Resistor Common Rail Power Supply 4

5 Electrical Test Equipment Despatch LBB series Ovens Wintel Computers (1 per 8 DUT boards) Matlab for experimental automation and data analysis USB Digital I/O (NIDAQ, 1 per 8 DUT boards) Laboratory Power Supplies (1 per 2 DUT board) MUX Mainframe (Keysight 34980A; 1 per 8 DUT boards) Form A Switch Card (1 per 2 DUT board) MUX Card (1 per 2 DUT board) LCR meter/impedance Analyzer (Keysight) Four Custom PCBs DUT Board (1 board contains 32 devices) Combo Board (1 per DUT board) Auxiliary Board (1 per mainframe) Custom Blank board 5

6 Squeezing out 64 instead of 35 channels Wiring of Analog Bus Pins ABus1 HI (Pin 9) Connects to ABus3 HI (Pin 7) ABus1 LO (Pin 4) Connects to ABus4 HI (Pin 6) ABus2 HI (Pin 8) Connects to ABus3 LO (Pin 2) ABus2 LO (Pin 3) Connects to ABus4 LO (Pin 1) Analog Bus output on back of 34980A MUX Mainframe allows for connection routing to expand available channel measurement capabilities Analog Bus High/Low lines for 3 & 4 are routed and flipped between ABUS 1 & 2 Combining this rerouting with single channels used for common lines (DUT common and Ground common), we in-effect get 64 channels instead of 35 with the same MUX card. 6

7 Generalized Circuit Diagram (64 Parts) 7

8 Test System Block Diagram Definition of a Single Unit Cell in Test Setup Computer Impedance Analyzer Power Supplies 34980A DMM/MUX Auxiliary Board Combo Boards Power Bus Digital/Automation Signals Test & Measure Signals DUT boards Oven 8

9 Voltage Step Stress Automated Test Flow START Take baseline ballast resistor measurements Wait for user input to continue. Raise to temp 1 Volt Applied to DUTs Sample all DUTs and temperature continuously Begin Life-Test / Start Timer Check Temperature. Continue when stable Step Voltage Wait for XX Seconds DC Testing Timer Loop Measure Voltage on all Ballast Resistors Update Saved Data and realtime plot Check for and Disconnect failed channels 9

10 DUT Board Mechanical Design BME capacitor DUTs are mounted on removable tabs along the edge of the board Tabs allow individual device to be removed for FA/DPA with minimized impact to ongoing test 4 wire (Kelvin connectors) to every node Removes cable parasitics Allows for future capacitance testing Size/configuration of DUT pads can easily be changed if needed DUT Board serial # serial # serial # serial # DUT DUT DUT N tabs DUT 10

11 Picture of Existing Electrical Test Setup 11

12 Electrical Limits and Accuracy 300 VDC max bias at 0.6A total current (across 64 DUTs) Multiple limits, board design, connectors, cables, relays in 34922A and 34939A cards Mainframe DMM voltage accuracy is % over 1 year over +/- 5C on 300 volt range 300 voltage range has voltage accuracy Assuming a 1 MΩ ballast resistor gives a ±16.5 na current accuracy Accuracy will be proportionally better in lower voltage ranges Similar percentage accuracy in all ranges Mainframe DMM 4 wire resistance accuracy is 0.01% over 1 year over +/- 5C on 1MΩ range 100 Ω accuracy on 1 MΩ range Accuracy will be proportionally better in lower voltage ranges Similar percentage accuracy in lower ranges Some reduction in percentage accuracy in 10 and 100 MΩ ranges Combined resistance and voltage accuracy % over 1 year over +/- 5 C on 300 volt range Assuming a 1 MΩ ballast resistor gives a ± 46.5 na current accuracy 12

13 Thermal Limits and Accuracy Oven set-point maximum is 200ºC Thermal characterization exists and reveals thermal tolerances at each DUT location. RTDs mounted at vertical center of DUT boards, closer to door than DUTs RTDs Generally run cooler than DUTs run in oven. Current measured thermal accuracy of +/- 3ºC across all DUTs in an oven Thermal accuracy at the RTD of +/ ºC at the RTD RTD tolerance of +/- 0.55ºC at 200ºC (worst case) DMM accuracy adds on additional +/ ºC (at 200ºC & 1000 Ohm RTD) Remaining error mostly due to oven circulation/design issues Significant thermal characterization data has been taken Special boards with RTDs in place of DUTs used to map out temperature Direct map of RTD temp to DUT temp may be possible to apply to final datasets 13

14 Summary Current Test System has capacity to test 832 DUTs at a time. Test System is currently operational, ready for full testing and expansion. Test system has gone through considerable characterization testing all last year. Nearly 3000 MLCC BMEs tested during characterization thus far. Currently performing final stages of thermal characterization. Costs relatively low, approximately $40k per 256 parts at a time (oven dependent). Currently have thousands more parts waiting to be stress tested. Intent is to generate data useful to inform industry on reliability of BME MLCCs. 14

15 Acknowledgements Allyson Yarborough, project leader Wayne Martin, test system design Scott Nuccio, test software and system design John Scarpulla, test system design Can Quang Nguyen, oven modifications Susan Crain, circuit design, layout design, board assembly. Carl Ibscher, board layout design Rebecca Lin, data analysis code Megan Campbell, system build-out support and part acquisition. 15

16 End Backup/Replaced Slides Follow 2016 The Aerospace Corporation

17 Oven Mechanical Configuration 3 Rows of 9 Cards Shown w/ see-thru view of oven Despatch Oven LBB1-43A-1 (2 ovens total) 27 cards total 3.75 unit cells 17

18 Oven Mechanical Configuration Oven Door DUT Cards Cable Clamp Combo Cards Sullins Card Edge Despatch LBB1-43A-1 18 Inner Individual Card Support Cage

19 Oven Mechanical Configuration Side View of LBB1-43A Rear View of LBB1-43A Despatch Oven LBB1-43A-1 19

20 Oven Mechanical Configuration 2 Rows of 7 Cards Shown w/ see-thru view of oven Despatch Oven LBB1-23A-1 (2 ovens total) 14 cards total 1.75 unit cell 20

21 Oven Mechanical Configuration Side View of LBB1-23A Rear View of LBB1-23A-1 Despatch Oven LBB1-23A-1 21

22 Populated, Functioning and Installed Combo Board 22

23 Current Populated and Functioning Auxiliary Board 23

24 Current Functioning Setup 24

25 Completed Oven Configuration 25

26 Instrument Control & Data Acquisition Software Description Software is written in Matlab, compiled to windows executable. Call graph is depicted below: minfig.p pwroff.m switchset.m ramppretests.m VoltageRamp.m setupdaq.m setupmux.m readrampv.m chanshutdown.m setupramptest.m readtemp.m readres.m setupps.m readrampdata.m Similar dependencies exist for Constant Voltage Life Test Software 26

27 70 channel Multiplexer Card Agilent 34922A Ballast Common DUT Common RTD 70 2-wire channels (35 per bank) Each bank has an independent Power and Ground Connection The Analog Bus allows channels from different banks to be connected to the internal DMM for measurement. By measuring using both banks, 4-wire measurements Kelvin connections can be obtained. Ballast Common DUT Common RTD Devote 2 Channels on each side to commons 27