MLC Quality and Reliability Data 2777 Route 20 East Cazenovia, New York, Phone: (315) Fax: (315)

Transcription

1 MLC Quality and Reliability 777 Route East Cazenovia, New York, Phone: () 6-87 Fax: () m

2 Reliability General Manufacturing Process At each manufacturing step, defined process controls have been established. Statistical techniques are utilized to identify key parameters within processes and to reduce the variation of these parameters. Testing is completed according to the customer s specification. Typical screening includes MIL PRF-68 level testing as appropriate. Capacitance, Dissipation Factor, Dielectric Withstanding Voltage, Insulation Resistance, and Visual Inspection are examined on each lot. Multilayer Capacitor Process Control In addition to carefully selected in-process controls, a sample of capacitors from each lot of multilayer capacitors is micro-sectioned to verify structural integrity and the absence of voids, delaminations, cracks, or other defects. After completion of manufacturing parts may be subjected to DLI s Thermal Stress Screening to further confirm the absence of any latent defects. Finally, % screening for: Capacitance, Dissipation Factor, Dielectric Withstanding Voltage, Insulation Resistance and Visual defects is performed on each lot. Reliability Testing Equivalent Part Failure, Part Failure, MTBF, FITs Growing out of the military market, DLI has retained the rigid qualification and reliability standards which are required for military contracts and expected on commercial applications. DLI routinely performs accelerated testing on products to prove their long term reliability. The following pages contain summary Reliability Test for various product types of Multilayer Layer Capacitors. DLI uses MIL-PRF-68 as a guideline testing to verify key capacitor performance characteristics. Using the life test data presented the FR level symbol (S, R, P, M, L) and equivalent part failure rate can be determined using MIL-STD-6C. DLI performs calculations at a % confidence level and =. (consumers risk). Life testing is performed at the maximum rated voltage at the maximum rated temperature. An acceleration factor of 8: has been used to relate life test data obtained at % of rated voltage at maximum rated temperature, to rated voltage at rated temperature. This data is compiled for each product type and listed according to the time period in which the data was obtained. Using the life test data the Part Failure, p, can be determined through the application of MIL-HDBK-7F. A knowledge of the end use conditions is necessary for the calculations. The Part Failure, Mean Time Between, and in Time rates are related as shown below. p = / 6 hours = / Million hours MTBF = / p = hours / Failure FITs = p * = / hours = / Billion hours Mean Time To Failure Estimation MTTF (Mean-time-to-failure) is the basic measure of reliability for non-repairable items. It is analogous to the more familiar MTBF (Mean-to-Between-) used for systems which can be repaired and placed back in service after failure occurs. Generally, MTTF is calculated as MTTF = Total Cumulative Hours Total Failure Experienced Page

3 However for highly reliable parts, it is not uncommon that no failures will be experienced over the period of testing. In such cases, the above formula is inappropriate. This has been the case with DLI capacitors. It is possible, however to approximate a lower limit on the reliability of the part (in other words a figure to determine the product will last at least as long as ) using the following formula Total Cumulative Hours Lower Bound = - In (a) (See note ) where a is related to the confidence level for the estimate by Confidence = ( a)% Thus for % confidence, a =. Predicted Reliability Over Time is determined using the assumption that the reliability distribution is exponential. Given this assumption, the reliability at time t=k hours is calculated as Reliability = EXPONETIAL (-(Time/MTTF)) Note : For reference see Meeker, William Q and Escobar Luis A (8) Statistical Methods for Reliability John Wiley & Sons Publishers p 68 (ref formula 7.7) Page

4 Multi-Layer Capacitor Reliability Test Conditions Thermal Shock and Immersion Capacitors are Thermal Shocked in accordance with MIL-STD-, Method 7, condition A, with a temperature range from - C to + C. Following Thermal Shock, the capacitors are Immersion tested in accordance with MIL-STD-, Method, Test Condition B. The capacitors are cycled from a Hot Tap Water Bath at 6 C for minutes to a cold bath of sodium chloride and water at a temperature of C for minutes. Post Test Limits: Insulation Resistance Capacitance change ± % of Initial Value < the greater of.% or ±. pf of Initial Value for AH, CF, and NA materials < ± % of Initial Value for BL materials Dissipation Factor = Original Specification Resistance to Soldering Heat Capacitors are tested in accordance with MIL-STD-, Method. Capacitors are mounted on alumina substrates using SN6 solder. The substrate is dipped (up to the bottom of the substrate) to simulate a wave solder operation. Initial and final measurements of Capacitance, Dissipation Factor, and Insulation Resistance are recorded. Post Test Limits: Insulation Resistance Capacitance change + % of Initial Value < the greater of.% or +. pf of Initial Value for AH, CF, and NA materials < + % of Initial Value for BL materials Dissipation Factor = Original Specification Resistance to Moisture Capacitors are tested in accordance with MIL-STD-, Method 6. Capacitors are subjected to continuous cycles from -8% Relative Humidity at 6 C to 8-8% Relative Humidity at C with a Vdc bias applied. Initial and final measurements of Capacitance, and Insulation Resistance are recorded. Post Test Limits: Insulation Resistance Capacitance change + % of Initial Value < + the greater of.% or +. pf of Initial Value for AH, CF, and NA materials < + % of Initial Value for BL materials Page

5 Low Voltage Humidity Capacitors are tested in accordance with MIL-STD-, Method, Condition A. Capacitors are subjected to 8% Relative Humidity at 8 C for hours with a. Vdc bias applied. Initial and final measurements of Capacitance, and Insulation Resistance are recorded. Post Test Limits: Insulation Resistance Capacitance change + % of Initial Value < the greater of.% or +. pf of Initial Value for AH, CF, and NA materials. < % of Initial Value for BL materials Life Testing Capacitors are tested in accordance with MIL-STD-, Method 8, Condition A. Capacitors are subjected to C for hours with a dc bias voltage of times rated voltage with a maximum surge current of ma. Capacitors with a rated voltage > volts are tested at volts. This data is denoted below. Initial and final measurements of Capacitance, Dissipation Factor, and Insulation Resistance are recorded. Post Test Limits: Insulation Resistance Capacitance change + % of Initial Value < the greater of.% or +. pf of Initial Value for AH, CF, and NA materials < % of Initial Value for BL materials Page

6 MultiLayer Capacitors Reliability Summary Collection Period Number of Lots s Test Hours Cumulative Accelerated Test Hours % Failure FR Equivalent Failure (%/, hr) MTTF: % Confidence (hr) Reliability Predicted Reliability t= Years Life Testing - All Types CXXCF 6/6 - / 8,8,,6, %.%,,6.7% CXXAH 6/6 - / 68 6,,,6, %.%,8,,.7% CXXBL 6/6 - / 7 7,8,,, %.%,6,86.% CXXUL 6/6 / 8 6,,,7, %.%,8,.% Low Voltage Humidity 6/6 - / % All Types Resistance to Moisture 6/6 - / % All Types Resistance to Solder 6/6 - / 77 % Heat - All Types Thermal Shock & 6/6 - / 7 % Immersion - All Types Remarks:. There were three part failures for Low Voltage Humidity that occurred in 8. One failure occurred in testing on part type CAH. This failure was attributed to a process flaw and was isolated to one manufacturing lot that was not shipped to any customers. Corrective measures have been implemented and follow-up testing confirmed the effectiveness of the action taken. Two failures occurred in Low Voltage Humidity on part type C8BL. These occurred on an initial design of the product. This part type has been re-designed to eliminate this type of defect with no detrimental effects to the electrical performance of the product.. There were seven part failures for Resistance to Moisture testing that occurred in. All seven failures occurred in testing on one lot of part type C7CF. The failure was attributed to one lot of raw material which was at the low end of a specification. Subsequent corrective measures tightened the specification and followup testing confirmed the effectiveness of the action taken. Page 6

7 MultiLayer Capacitors Thermal Shock and Immersion Collection Period Temperature Characteristic Number of Lots s s Cumulative % Failure 6/6 - / All Types 7.% /7 - / C6 CF % / - / /7 - / 6/6 - / 6/6 - / 6/6 - / 6/6 - / /7 - / /7 - / C6 BL C6 UL 6 C8 BL 7 C AH C CF C UL C7 AH 7 C7 CF C7 UL 7 6 C CF C AH % 8.%.% 86.% 77.%.% 6.%.% 8.%.%.% Page 7

8 MultiLayer Capacitors Resistance to Soldering Heat Collection Period Temperature Characteristic Number of Lots s s Cumulative % Failure 6/6 - / All Types 77.% /7 - / C6 CF % / - / /7 - / 6/6 - / 6/6 - / 6/6 - / 6/6 - / /7 - / /7 - / C6 BL C6 UL C8 BL C AH C CF C UL C7 AH 86 C7 CF C7 UL 7 6 C CF C AH % 7.%.% 6.%.% 6.% 8.%.% 6.% 8.%.% Page 8

9 MultiLayer Capacitors Resistance to Moisture Collection Period Temperature Characteristic Number of Lots s s Cumulative % Failure 6/6 - / All Types 88 7.% /7 - / C6 CF % / - / /7 - / 6/6 - / 6/6 - / 6/6 - / 6/6 - / /7 / /7 - / C6 BL C6 UL C8 BL 7 C AH C CF 7 C UL C7 AH 8 C7 CF C7 UL 7 6 C CF CAH % 7.%.%.% 6.% 6.% 78.% % 6.% 6.%.% Page

10 MultiLayer Capacitors Low Voltage Humidity Collection Period Temperature Characteristic Number of Lots s s Cumulative % Failure 6/6 - / All Types 67 6.% /7 - / C6 CF % 6/ - / /7 - / 6/6 - / 6/6 - / 6/6 - / 6/6 - / /7 / /7 - / C6 BL C6 UL C8 BL 7 C AH C CF C UL C7 AH 8 C7 CF C UL 7 6 C CF C AH % 6.% 6.8%.% 7.% 8.% 8.% 7.% 68.%.% 6.% Page

11 MultiLayer Capacitors Life Testing Collection Temperature Period Characteristic 6/6 - / All Types Number of Lots s 6, Total Test Hour,8, Cumulative Accelerated Test Hours 7,6, Equivalent Failure MTTF: % Confidence Reliability Reliability t = years /7 - / / - / /7 - / 6/6 - / 6/6 - / CXXCF CXXAH CXXBL CXXUL C6 CF C6 BL C6 UL 6 7 C8 BL 7 C AH 7 C CF C UL 6 6, 6,6,, ,8,,,,8,,,,66,, 88,,6,,6,,,,7,.%.%.%.%,,6,8,,6,86,8,.7%.7%.%.% 6, 8,88,.% 6,, 8.6%,, 88, 88, 88,,8,.%,67,6 7.7% 8, 66, 76,,6,.%,,7 7.6%,78, 6, 88, 76,,6,.% 7,, 8.8%,6, 6, 88, 88,,6,.%,87,.%,7,, 76, 6,,,.% 8,,6.%,6, 8, 88,,76,.%,6, 8.% Page

12 6/6 - / 6/6 - / /7 / /8 - / C7 AH 8 C7 CF C7 UL 7 6 C CF CAH ,8, 6, 88, 88,,8, 76, 6,,. Capacitors with rated voltage greater than volts are tested at volts dc.. Equivalent Failure determined from MIL-PRF-68 in conjunction with MIL-STD-6,8,.% 7,86,7.%,8,.%,,8.% 66, 8, 88,,86,.%,,6 7.%,,, 88, 88,,8,.%,7, 8.%,86,, 88, 88,,6,.% 6,,8 8.7% Page

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