Quality assurance and reliability Diodes Quality assurance and reliability zROHM product quality We put quality first “Quality” here refers to both the integrity of the products that we manufacture and price and timely delivery of those products to our customers. Although we put the utmost effort into each one of these factors, we give particular emphasis to the integrity of the product. We are striving to minimize defects in our semiconductor devices both at the initial defect stage and at the incidental defect stage. The incidental defect rate is approaching a constant value. Most device manufacturers are approaching the same level in products where there are no major design problems. Therefore, we are making supreme efforts to bring semiconductor devices to our customers which have already been appropriately screened. By eliminating devices with hidden defects, we have reduced our customer-perceived defect rate λi to a level as close as possible to the incidental defect rate λr. These efforts insure that our customers are receiving products with a minimum defect rate. Our products have earned a reputation for their high reliability with our customers. zQuality assurance activities (1) Education and training In accordance with the fundamental goals of our company, we educate and train all our personnel in every division so they can produce reliable, quality products. Particular emphasis is placed on quality control, production control, research and design, purchasing, manufacturing, and management. (2) Inspection and calibration All measuring devices used in manufacturing process undergo periodic inspection and recalibration based on our own critical measuring device standards. (3) Manufacturing control ROHM has developed internal standards to control materials testing, manufacturing conditions, inspection methods, and other operations. Additionally, dust, humidity and temperature are strictly controlled in the manufacturing areas, in accordance with ROHM standards. zQuality assurance system Our quality assurance system requires testing at each major step in the manufacturing process. In addition, precise inspections are conducted after final assembly. For example, after the wafers are processed, the electrical characteristics of the wafers are measured to gauge the accuracy of each process. A short-term endurance test is carried out on each wafer. These tests allow us to assure the reliability of the wafers. After the diodes are assembled, we ensure the quality of all products by conducting multiple measurements at a high degree of precision. Fig. 1 shows our system for quality assurance. Rev.A 1/5 Quality assurance and reliability Diodes zReliability testing In order to verify the reliability of the finished products and the state of the quality control program for the entire manufacturing process, we periodically carry out reliability test on the products that we manufacture. Table 1 No. Test Test conditions Immersion for 1 Solderability 5 seconds in 230°C solder bath Tolerance Length of solder on lead must be > 1 mm Pull terminal lead with 500g load terminal lead for 5 seconds Tensile Immerse 1.5mm of terminal lead in 350°C solder bath 4 Boiling 5 hours at 100°C Solder heat 20 of Tstg (Min.) / Ta / Tstg (Max.) JIS C 7021 A-4 Thermal 15 of −65°C (5') / 100°C (5') JIS C 7021 A-3 6 shock Pressure cooker 125°C and atmospheric pressure of 2 at relative humidity of 85%, for 4 hours Exposure to high Ta=85°C 8 temperature RH=85%, and humidity for 1,000 hours 9 Aging test at high temperature Small signal 10 diode load life Constant Ta=Tstg (Max.), for 1,000 hours Ta=25°C, IF=IO for 1.5 hours on, 0.5 hours off, repeated over 1,000 hours Ta=25°C operation Rectifier 12 diode continuous operation Variable capacitance diode, high temperature reverse bias life VF <U ∗ × 1.1 IR <U ∗ × 2.0 JIS C 7021 B-11 JIS C 7021 ∆V2 : 2% B-10 No mechanical damage JIS C 7021 for 1,000 hours JIS C 7021 B-2 IF=IO Ta≤Tj (Max.), for 1,000 hours JIS C 7021 B-13 VR=VRM Ta≤Tj (Max.), for 1,000 hours JIS C 7021 B-3 diode Pd=Pd (Max.), 11 voltage continuous 13 JIS C 7021 A-1 Thermal 5 cycling 7 JIS C 7021 A-2 JIS C 7021 A-11 2 strength of 3 resistance Related standards ∗ U : Upper limit of standard Rev.A 2/5 Quality assurance and reliability Diodes zDiode quality assurance system Related divisions Related divisions 1 1. Receive the raw materials Monitor quality at manufacturing at supplier's factory. Confirm receipt of monthly quality report. 2 2. Inspect the raw materials Inspect samples of the raw material batch, and conduct physical and chemical analysis. 3 3. Manufacture the wafers Initiate in-process quality control. 4 4. Inspect the pellets Exterior inspection and measurement of electrical characteristics. 5 5. Quality assurance testing Assess yield by inspecting first assemblies. Test short term endurance and static characteristics. 6 6. Assemble the diodes Initiate in-process quality control. 7. Screen the diodes Screen all products by testing electrical and thermal properties. 8. Inspect all diodes Inspect exterior and electrical characteristics on all products. 9. Inspect product Inspect exterior and electrical characteristics on random sampling of products. 7 8 Quality assurance testing 9 10. Ship products 10 Fig. 1 Quality assurance testing system zPredicting reliability One of the most frequently used methods for predicting reliability of electronic components is described in MILHDBK-217F, “Prediction of Reliability in Electronic Devices”. For your reference, we will summarize the section related to semiconductor devices. zPredicting the failure rate in discrete semiconductor devices The model shown here predicts the failure rate of low-frequency diodes. This model predicts the failure rate (λp) for discrete semiconductor devices using the formula : λp=λb×πT×πS×πC×πQ×πE / 106 hr where : λb=The basic failure rate shown in Table 2 determined by diode type and application. πT=Temperature factor (Tables 3 and 4) πS=Electrical stress factor (Table 5) πC=Contact structure factor (Table 6) πQ=Quality factor (Table 7) πE=Environmental factor (Table 8) Table 2. Basic failure rate model (λb) λb Diode type/application Analog diode, for general use .0038 Switching diode .0010 Power rectifier, for fast recovery .069 Power rectifier, Schottky power diode .0030 High-voltage, multi-layered power rectifier Transient suppressor/varistor diode Current regulator Voltage regulator and standard voltage application (avalanche and Zener diodes) .005 / junction .0013 .0034 .0020 Rev.A 3/5 Quality assurance and reliability Diodes Table 3. Temperature factor (πT) (Applicable to voltage regulator, standard voltage application, and current regulator diodes) πT Tj (˚C) 1.0 1.1 1.2 1.4 1.5 1.6 1.8 2.0 2.1 2.3 2.5 2.7 3.0 3.2 3.4 3.7 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 πT =exp −1925 Tj (˚C) πT Tj (˚C) πT Tj (˚C) 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 3.9 4.2 4.5 4.8 5.1 5.4 5.7 6.0 6.4 6.7 7.1 7.5 7.9 8.3 8.7 < 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 1.0 1.2 1.4 1.6 1.9 2.2 2.6 3.0 3.4 3.9 4.4 5.0 5.7 6.4 7.2 8.0 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 1 1 − Tj+273 298 πT =exp −3091 Tj=Junction temperature (˚C) S, Stress 9.0 10 11 12 14 15 16 18 20 21 23 25 28 30 32 1 − 1 Tj+273 298 Table 6. Contact structure factor (πC) πs Contact structure πC Metal connectors 1.0 Non-metallic connectors and spring-loaded contacts 2.0 1.0 All others Vs≤.30 .3<Vs≤.40 .4<Vs≤.50 .5<Vs≤.60 .6<Vs≤.70 .7<Vs≤.80 .8<Vs≤.90 .9<Vs≤.1.0 πT Tj=Junction temperature (˚C) Table 5. Electrical stress factor (πs) Transient suppressor, voltage regulator, standard voltage application, and current regulator Table 4. Temperature factor (πT) (Applicable to analog for general use, switching, fast recovery, power rectifier, and transient suppressor diodes) 0.054 0.11 0.19 0.29 0.42 0.58 0.77 1.0 Quality factor=2.4 (from MIL-HDBK-217F) Enviroment factor=9.0 (from MIL-HDBK-217F) For all except transient suppressor, voltage regulator, standard voltage application, and current regulator diodes: πs =0.54 (Vs≤.3) πs =Vs 2.43 (.3<Vs≤1) Applied voltage Constant voltage Voltage is diode reverse voltage. Vs=Voltage stress ratio= Rev.A 4/5 Quality assurance and reliability Diodes Table 8. Environment factors (πE) Table 7. Quality factors (πQ) Quality JANTXV JANTX JAN Lower quality Plastic πQ 0.7 1.0 2.4 5.5 8.0 πE Environment GB GF GM Ground, benign Ground, fixed Ground, mobile 1.0 6.0 9.0 NS NU Naval, sheltered Naval, unsheltered 9.0 19 AIC AIF AUC AUF ARW Airbone, inhabited, cargo Airbone, inhabited, fighter Airbone, uninhabited, cargo Airbone, uninhabited, fighter Airbone, rotary winged 13 29 20 43 24 SF MF ML CL Space, flight Missile, free flight Missile, launch Cannon, launch .50 14 32 320 zExample of predicted failure rate calculations [Question] What would be the Predicted faibure rate for a switching diode (Specifications DO-35 package, TMax.=175°C, P=500mW, quality equivalence : JAN grade, contact structure : non-metallic alloy and spring –loaded contact) operated at a case temperature of 62%, a rated load of 60%, a constant voltage of 30%, and a room temperature of Ta=25°C? [Calculation] (1) Because this is a switching diode, λb=0.0010 (based on Table 2). (2) P=500mW with a load of 50%, at a case temperature of 55°C. Tj=Tc+∗θJCP =62°C+10°C / W×0.30W=65°C where πT=3.4, based on Table 4. (3) From Table 5 : πS=0.054 (4) From Table 6 : πC=2.0 (5) From Table 7 : πQ=2.4 (6) From Table 8 : πE=9.0 (7) λp=λb×πT×πS×πC×πQ×πE/106hours = 0.0079/106hours = 7.9 ∗ θJC is the junction-to-case thermal resistance of a diode with a case similar to the DO-35 package. Rev.A 5/5 Appendix Notes No technical content pages of this document may be reproduced in any form or transmitted by any means without prior permission of ROHM CO.,LTD. The contents described herein are subject to change without notice. The specifications for the product described in this document are for reference only. Upon actual use, therefore, please request that specifications to be separately delivered. Application circuit diagrams and circuit constants contained herein are shown as examples of standard use and operation. Please pay careful attention to the peripheral conditions when designing circuits and deciding upon circuit constants in the set. Any data, including, but not limited to application circuit diagrams information, described herein are intended only as illustrations of such devices and not as the specifications for such devices. ROHM CO.,LTD. disclaims any warranty that any use of such devices shall be free from infringement of any third party's intellectual property rights or other proprietary rights, and further, assumes no liability of whatsoever nature in the event of any such infringement, or arising from or connected with or related to the use of such devices. Upon the sale of any such devices, other than for buyer's right to use such devices itself, resell or otherwise dispose of the same, no express or implied right or license to practice or commercially exploit any intellectual property rights or other proprietary rights owned or controlled by ROHM CO., LTD. is granted to any such buyer. Products listed in this document are no antiradiation design. The products listed in this document are designed to be used with ordinary electronic equipment or devices (such as audio visual equipment, office-automation equipment, communications devices, electrical appliances and electronic toys). Should you intend to use these products with equipment or devices which require an extremely high level of reliability and the malfunction of with would directly endanger human life (such as medical instruments, transportation equipment, aerospace machinery, nuclear-reactor controllers, fuel controllers and other safety devices), please be sure to consult with our sales representative in advance. About Export Control Order in Japan Products described herein are the objects of controlled goods in Annex 1 (Item 16) of Export Trade Control Order in Japan. In case of export from Japan, please confirm if it applies to "objective" criteria or an "informed" (by MITI clause) on the basis of "catch all controls for Non-Proliferation of Weapons of Mass Destruction. Appendix1-Rev1.1