Developing Automotive grade MLCC for Space Applications

Transcription

1 Developing Automotive grade MLCC for Space Applications 民生部品 ( 車載用 ) をヘ ースとした宇宙用積層セラミックチッフ コンテ ンサの開発 MEWS MURATA MFG.CO., LTD. Kunio Tachi 舘邦夫 1

2 CONTENTS 1)Background 2) Present situation of current MLCC for Space 3)Trend of dielectric thickness for consumer application 4)Technology to achieve thinner dielectric films 5)Collaboration with JAXA MLCC for Space application by using Automotive Grade MLCC 6)Automotive Grade & Space Grade Process Chart 7)Capacitance Range for Space Grade Capacitors 8)Data of Space Grade Capacitors 9)Conclusions 2

3 Background 1)Current MLCC(Multi-Layer Ceramic Capacitors) for Space application are designed by using special material (ceramic/electrode/resin ) and design rule. So, it is very difficult to cost reduction and also becomes difficult to get special material (ceramic/electrode/resin ). 2)And, order intake of MLCC for Space has been decreased. But it needs stability of supply, and Pb free. 3)We(MURATA )shipment history to the automotive market for the past 2 years has been slightly over 20 billion pcs a year. The field failure rate of capacitors shipped to automotive customers was 1.2ppb. 4)JAXA and MURATA have joined hands in developing MLCC for space applications based on existing automotive grade capacitors. 3

4 JAXA(NASDA) SPEC. Ceramic Capacitor NASDA CKS/1002S Type NASDA CDS Type 4

5 Sales Trend of Capacitor for Space application <Kpcs/half year> F1 95F2 96F1 96F2 97F1 97F2 98F1 98F2 99F1 99F2 00F1 00F2 01F1 01F2 02F1 02F2 03F1 03F2 04F1 04F2 05F1 CKS/1002S(RK-R) CDS(GRH-R/GR-R)

6 1. Trend of dielectric thickness for consumer applications 6

7 Trend of dielectric thickness (for consumer applications) 100 Dielectric Thickness ( µm ) Size-1uF-16V(9μm) 0805 Size-10uF6.3V(1.7μm) 1206 Size-10uF- 25V(3μm) 0603 Size-10uF-6.3V(1μm) year 7

8 Trend of Rated Voltage and Size 10 Rated Voltage (V/µm) Size-0.1uF-50V 1206 Size-0.1uF-50V 0201 Size-0.1uF-10V 0402 Size-0.1uF-10V 0603 Size-0.1uF-16V 0805 Size-0.1uF-25V year 8

9 2. Technology to achieve thinner dielectric films 9

10 Technology to achieve thinner dielectric films Unevenness of inner electrode Dielectric layer Similar technology would lead to Pore Areas of non-uniform composition Inner electrode Low withstanding voltage, shorter life, poor reliability, etc. New technology Technologies to achieve thinner dielectric; Mainly 1)Fine ceramic powder 2)High density of green film 3)Uniformity of Composition 4)Thin and smooth electrode 10

11 Internal Structure of MLCC with latest Technology 500um Cross section of 0603 Size X5R 10uF 6.3V Number of Dielectric layers:320 Inner electrode :Ni Fine and uniform grains Thin and dense dielectric layer Thin and smooth electrode FE-SEM Picture 11

12 Schematic of a Multi Layer Ceramic Capacitor Termination 1st layer 2nd layer 3rd layer Inner electrode Precious Metals Electrode Products Base Metals Electrode Products Inner electode Pd or Ag/Pd Ni Termination 1st layer Ag/Pd or Ag Cu (or Ag/Pd) 2nd layer Ni Ni 3rd layer Sn Sn

13 3. Collaboration with JAXA MLCC for Space Application by using Automotive Grade MLCC 13

14 Automotive Grade & Space Grade Process Chart INCOMING INSP. OF CERAMIC MATERIAL MIXING DE-AIRING SHEET CASTING CUTTING FIRING TERMINATION TERMINATION FIRING ELECTRODE PRINTING TERMINATION PLANTING STACKING & PRESSING SORTING OUTGOING INSPECTION SAM & BURN-IN SORTING GROUP A INSPCTION GROUP B/C INSPCTION (Periodical) AUTOMOTIVE Grade Addition for SPACE Grade SPACE Grade 14

15 SAM (Scanning Acoustic Microscope) Transducer Defect position Water SAM Picture of Failure Void Crack Resolution X-Y direction : 10μm Z direction : 10μm 15

16 Reliability of Automotive Grade capacitor Sample :1206Size X7R 224K 50V Dielectric Thickness :16um Test condition :125C-200V Number of sample units:72pcs-4lots=288 Duration :3,000hours at125c-50v Confidence Level 60% Acceleration Factor Voltage: 3.5 Temperature:8C FR Coefficient Number of sample = Total Number of hours = *3000*Acceleration Factor(128*1) =8.3*10-9 Voltage Acceleration = (200/50)^3.5 =128 Temperature Acceleration=2^(( )/8)=1 =8.3Fit Failure level Symbol : S (0.001%/1000hrs=10Fit) 16

17 Capacitance Range & Dielectric Thickness for Space Grade Capacitors TC RATED VOLTAGE(V) CAP.RANGE DIELECTRIC THICKNESS(μm) COG 50 0R5~332 18~ ~182 25~ ~391 52~142 X7R ~225 15~ ~105 16~ ~474 22(SERIES)~ ~224 24(SERIES)~28(SERIES) ~104 33(SERIES)~37(SERIES) MIL-PRF-123C MIN DIELECTRIC THICKNESS :0.8mil(20μm) for 50V or 1mil(25.4μm) for ratings above 50V 17

18 Test Sample for Space MLCC NO SIZE(mm) TC CAP WV COG 332K COG 182K COG 391K X7R 105K X7R 225K X7R 474K X7R 105K X7R 224K X7R 474K X7R 224K X7R 104K 500 Automotive Grade Space Grade WV 1/2WV ex. 200V 100V 18

19 Qualification Inspection for Space MLCC to JAXA Group Item Test Condition Result Ⅰ Thermal shock and voltage conditioning cycle & 125 2WV 168HR 0/245 Dielectric withstanding voltage 2.5WV 5sec Insulation resistance(25 /125 ) WV 120sec Cap,DF COG(1000pFover)&X7R:1kHz1v,COG(1000pFless):1MHz1V Ⅱ Visual,Dimension Visual inspection,using calipers 0/15 Destructive physical analysis Cutting,Grinding Ⅲ Terminal strength MIL-STD-202 method 211 0/4 Solderability of Termination MIL-STD-202 method sec 0/4 Resistance to Soldering Heat MIL-STD-202 method sec 0/4 Ⅳ Voltage temperature limits +25/-55/-125 WV 0/12 Moisture resistance MIL-STD-202 method cycle 50VorWV Ⅴ Humidity Steady State Low voltage MIL-STD-202 method 106A 85 85%RH 240HR 1.3V 0/12 Vibration MIL-STD-202 method 213/214 0/10 Thermal shock MIL-STD-202 method cycle 0/18 Ⅵ Life MIL-STD-202 method WV 4000HR 0/123 19

20 1206 COG332K50(t= 0.7mil< 18μm>) LIFE TEST(125 2WV 4000HR n=123pcs) IR log.ir All 12.0 over Initial [Hr] 20

21 1210 X7R105K25(t= 0.6mil< 15μm m >) LIFE TEST(125 2WV 4000HR n=123pcs) IR log.ir Initial [Hr] 21

22 1812 X7R225K25(t= 0.6mil< 15μm m >) LIFE TEST(125 2WV 4000HR n=123pcs) IR log.ir Initial [Hr] 22

23 1812 X7R225K25(t= 0.6mil< 15μm m >) THERMAL SHOCK( n=18pcs) IR log.ir [cycle] 23

24 1812 X7R225K25 (t=0.6mil<15μm>) m>) Humidity steady state low voltage (85 85%RH 1.3V 240Hr n=12pcs) IR log.ir Initial After 24

25 Tin Whisker(Thermal shock cycle) 1000cycle) 1GRK-R42-6COG332K50 2GRK-R42-6COG182K100 3GRK-R42-6COG391K200 25

26 Conclusions 1. JAXA and MURATA have co-developed MLCC for Space applications derived from existing Automotive grade capacitors (SAM and additional burn in tests). 2. Although, the dielectric thickness of MLCC for Space application is below 0.8mil (MIL- PRF-123C spec.), our tests show the reliability to be high and meeting MIL life test condition(125 2WV 4000HR ). 26

27 APPENDIX 27

28 Shipping History (1) Murata has been supplying MLCC with nickel internal electrodes (Nickel Electrode Material) to the automotive market for over five years now. (2) The MLCC industry as a whole supplied about 700 Billion capacitors in (3) Murata s shipment history to the automotive market for the past 2 years has been slightly over 20 billion pieces a year. (4) The field failure rate of capacitors shipped to automotive customers was 1.2 ppb (past 2 years). (5) Furthermore, very few of those failures could be related to reliability problems concerning the dielectric film or material. This corroborates our findings in this study that MLCC made with dielectric films thinner than MIL spec of 20μm are reliable enough to be used in Hi-Rel applications (including automotive). 28

29 Reliability of Ni and Pd electrode MLCC 1E+6 HIGH TEMPERATURE LOAD 0805 Size X7R 100nF 25V n=18pcs 1E+6 Pd electrode Ni electrode HUMIDITY LOAD n=18pcs 1E+5 1E+5 I.R. (M ohm) 1E+4 1E+3 I.R. (M ohm) 1E+4 1E+3 1E+2 INITIAL AFTER TEST 1E+2 INITIAL AFTER TEST TEST CONDITION: TEMPERATURE : 125 +/- 3deg. C VOLTAGE : 50 VDC DURATION : /- 12 HOURS TEST CONDITION: TEMPERATURE : 40 +/- 2deg. C HUMIDITY : 90 ~ 95%RH VOLTAGE : 25 VDC DURATION : 500 +/- 12 HOURS 29

30 Key factors of New Technology Key factors 1)Fine ceramic powder 2)High density of green film 3)Uniformity of Composition 4)Thin and smooth electrode Fineness of raw materials, Mixing, High Crystallinity Dispersant, Binder & Casting conditions Composition and Uniform dispersion of dopants Anti-oxidant fine metal powder, Paste Rheology 30

31 1) Fine ceramic powder Particle Size Distribution of Ceramic powder 31

32 2) High density of green film Pore Former High density Fine ceramic powder Current 2um FE-SEM: Surface of green film 32

33 High density of green Sheet Former Current 2um Pore FIB-SIM: Cross section of green film 33

34 FIB-SIM FIB:Focused Ion Beam SIM:Scanning Ion Microscope Ga Ion Beam Angle of incidence : 5deg. Detector Green Sheet Angle of observation picture : 45deg. SIM-Picture 34

35 3) Uniformity of Composition Former agglomeration Current Uniformity of green film WDX Mapping of Mn (dopant material) 35

36 4) Thin and smooth electrode Former Current 2um FIB-SIM: Cross section of green chip 36

37 Thin and smooth electrode Former Max peak : um Current Max peak : <0.5um Surface roughness of inner electrode 37

38 Highly Accelerated Life Test (HALT) Weibull distribution Sample :1206Size X7R 224K 50V Dielectric Thickness :16um Test condition :150C-400V Number of sample units:18 m-parameter : 2.96 MTTF : 224hrs Estimated MTTF at 125C,100%RV : 322years Acceleration Factor Voltage: 3.5 Temperature:8C 38

39 MLCC Reliability Design (1) Voltage Acceleration : Eyring Model L = C xv -a Hereby is L : Lifetime C : Constant V : Test Voltage a : Acceleration Factor AL = LN /LA = (VA /VN) n Hereby is AL : Acceleration Factor LN : Lifetime under Standard Condition LA : Lifetime under Accelerated Condition VN: Temperature Standard Condition VA: Temperature Accelerated Condition n : Voltage Acceleration Factor 39

40 MLCC Reliability Design (2) Temperature Acceleration: Ahrenius model L = C X exp { -Ea/(k XT) } Hereby is L : Lifetime C : Constant Ea : Activated Energy k : Boltzmann Factor T : Absolute Temperature AL = LN /LA = 2 ( t/b ) Hereby is AL : Acceleration Factor LN : Lifetime under Standard Condition LA : Lifetime under Accelerated Condition t : Temperature Difference between Standard & Accelerated Condition b : Temperature Acceleration Factor 40

41 Introduction of anti-deoxidization ceramics Technique for base metal inner electrode Apply base metal(ni) Firing in the deoxidization atmosphere Following point are required - anti-deoxidization of dielectric. - improve reliability. 41