IPC-TM-650 Test Methods Manual

1 The Institute for Interconnecting and Packaging Electronic Circuits2215 Sanders Road Northbrook IL 60062-6135 IPC-TM-650 Test Methods ManualMaterial in the Test Methods Manual was voluntarily established by Technical Committees of the IPC. This material is advisory onlyand its use or adaptation is entirely voluntary. IPC disclaims all liability of any kind as to the use, application, or adaptation of thismaterial. Users are also wholly responsible for protecting themselves against all claims or liabilities for patent infringement. Equipmentreferenced is for the convenience of the user and does not imply endorsement by the DC Current Induced Thermal Cycling TestDate 11/99 RevisionProposalOriginating Committee: Test Methods Subcommittee (7-11)Page 1 of Scope This test measures changes in resistanceof plated-through hole barrels and internal layerconnections as holes are subjected to thermalcycling.

2 Thermal cycling is produced by theapplication of a current through a specific this technique, the test coupon is resistance heatedby passing DC current through the internal layerconnection to the barrel for 3 minutes to bring thetemperature of the copper to a designated temperature(slightly above the Tg of the laminate in the sample.)Switching the current on and off, creates thermalcycles between room temperature and the designatedtemperature within the sample. This thermal cyclinginduces cyclic fatigue strain in the plated-through holebarrels and internal layer interconnects andaccelerates any infant mortality or latent number of cycles achieved permits a quantitativeassessment of the performance of the information regarding the test is found in theNOTES Applicable IPC-TM-650 , Method , IPC-TM-650 , Method ,Microsectioning -Semi or Automatic Test Specimens Daisy chain test coupon perFigure 1.

3 See Note Apparatus or Interconnect Stress Test System (IST) See Two (2) Four pin, ( inch) pitch maleconnectors (MOLEX 2241-4042 or equivalent) Sn60Pb40 or Sn63Pb37 Solder Soldering Multimeter - Thermal Imaging equipment - Sample Solder two 4 pin male connectors in the holes at left and right edges of side 1. A solderfillet must be apparent on both sides of the Allow coupons to come to room temperature(approximately 10 minutes), prior to installation ontoIST IST Position coupons at each test head by attachingmale to female Provide system software with specific testconditions. The available ranges and typical conditionsare as follows: IPC-TM-650 Number Stress Technology (IST)Date 11/99 Revision ProposalPage 2 of 4 ConditionsIST RangeTypicalNo.

4 Of samples1-66 Test Temp50 C to 250 C150 C(122 F to 422 F)(302 F)Max. Res. Chng1-100%10%Max No. Cycles1-4000250 (1 day)Data Coll. cycles10 cyclesCooling heat Enter a data file name and begin the pre-cycletest sequence. When the pre-cycle sequence iscomplete, the IST system begins the thermal cyclingof the coupons. Enter a file name and begin test. TheIST system continuously monitors the coupons andrecords the relative changes in resistance of both thebarrel and the internal layer connections. Data iscompiled for each coupon s performance throughoutIST stress testing. The system software provides adownload file to graph the coupon s performance.

5 Datais compiled to create graphs of each coupon sperformance throughout IST stress Microsection Evaluation - Optional If detailedfailure analysis is desired to determine exact locationof separations and/or cracks. A multimeter or athermal imaging system can aid in identifying thefailure location. Microsection of failed coupons shall beperformed in accordance with IPC-TM-650 , or IST SYSTEM DETAILSThis equipment is available from:PWB Interconnect Solutions Stafford Rd W Unit 105 Nepean, Ontario Canada K2H 9C1(613)-596-4244 URL: IST Coupon. Certain design rules mustbe applied to achieve thermal uniformity. Electronicdesign files for coupon construction are available fromthe IPC office.

6 The coupon resistance should measurebetween 150 milliohms and ohms when measuredat room temperature. Two resistance values (voltagedrops) for each coupon are monitored independently,using a four wire measurement test coupon(s) is incorporated on the panel tomonitor or qualify design, materials or processes andprovide risk assessment of product and/or Detailed Description of Pre Cycling Test following paragraphs detail the sequence for asingle coupon, however this sequence is done at alltest heads simultaneously. The ambient resistance,target temperature resistance, rejection resistance andcurrent is calculated for each coupon and displayed onthe PC : Handling the coupons will raise thetemperature of the coupon and may affect the ambientresistance calculation during the precycling the ambient temperature of the coupons is inquestion, cool the coupons with the fans on the ISTequipment for 1 - 2 Ambient Resistance The auto rangingmultimeter measures the ambient resistance (voltagedrop) of the coupon.

7 This is the circuit that heats thecoupon with DC Target Temperature Resistance Thesystem software calculates and displays the required target resistance (temperature). The available stresstesting range is from 50 C - 250 C (122 F - 422 F).The equation used to calculate the target resistance isas follows:Target Resistance = Rrm (1 + T[Th - Trm ])where: T = Estimated thermal coefficient of resistance forthe interconnectRrm = Resistance of coupon at room temp(approximately 25C)Th = Specified temperature to be = Room Rejection Resistance The rejectionresistance is calculated and displayed. This isadjustable from 1 - 100% increase.

8 If 10% is selected,10% of the target resistance is calculated and addedto the original resistance to establish the Stress Technology (IST)Date11/99 Revision ProposalPage 3 of Current The system selects an initial currentbased on the ambient resistance of the coupon and thecurrent table. The current tables are derived fromsoftware libraries on the IST equipment. During theprecycling sequence, the initial current is adjusted foreach coupon to assure the test temperature resistanceis achieved in 3 minutes + 3 seconds (see )NOTE: Additional equations/algorithms used by ISTthat establish the initial current selection for pre-cycling, relative to the relationship of couponinterconnect resistance T , coupon construction andstress test temperature to be achieved are consideredproprietary at this Pre-cycling is initiated by the application of theselected current to the coupon, the computer monitorsand records the coupon s performance throughout thisfirst cycle.

9 If at the end of the 1st pre-cycle, thecoupon achieves the specified resistance level in 3minutes + 3 seconds, it will be accepted forsubsequent stress testing. If the resistance level wasnot achieved in this time frame, the coupon willautomatically be pre-cycled again with a revised orcompensated current. The system will re-test usingrevised conditions until all coupons are accepted orrejected for stress : The equation/algorithms used by IST tocompensate the DC current is considered proprietaryat this Forced air cooling is commenced after eachpre-cycle to cool the coupons. (Requires minutes) The system automatically records and savesall information regarding conditions for subsequentstress Stress Cycle Test The stress test is initiated by re-applying thesame DC current level established for each individualcoupon during the pre-cycle operation.

10 Three minutesof heating is followed by two to three minutes ofcooling. Cooling time is a function of overall thicknessand construction of the Individual coupons are continually recycledusing their customized heating and cooling conditionsuntil one of the rejection criteria is achieved or themaximum number of cycles is The coupon s resistance delta (variance frominitial calculated resistance) increases (positively) asfailure inception occurs. The rate of change in thedelta is indicative of the mechanical change (failure)within the When each coupon delta reaches themaximum resistance rejection criteria, IST stresstesting is stopped.