Critical Issues on the Way to RoHS Conformity

Transcription

1 Critical Issues on the Way to Conformity 1 Metal Parts Analysis Supply Chain Data Inquiry Analysis (Unspecific Product Example) 1. Mainframe (Metal Parts) Housing/ Frame Screws / Bolts etc. Non--Compliant Contents: Chromium VI, Cd, Pb Check for Alternatives -compliant alternatives available for most parts 2 Source: Zollner Elektronik AG 2004 (modified)

2 Plastics Parts Analysis Supply Chain Data Inquiry Analysis (Unspecific Product Example) 2. Mainframe (Plastics Parts) Housing Front panels etc. Non--Compliant Contents: PBB or PBDE as flame retardants? Check for Alternatives PBB and PBDE free plastics available (Bayer, BASF ) 3 Source: Zollner Elektronik AG 2004 (modified) Compliance What You Have to Consider Analysis (Unspecific Product Example) 1. Mainframe (Metal Parts) 3. Components Supply Chain Data Inquiry 2. Mainframe (Plastics Parts) 4. PWB Assembly 4 Source: Zollner Elektronik AG 2004 (modified)

3 Material Variety Example Reflow Solders, SnAg Reflow EU, SnAg, Bi-containing solders Reflow Japan Don't know 20% SnBi 4% SnAg 8% Others 4% 64% SnCu 1% SnAgBi 3% Bi 5% SnZnBi 9% SnAg 9% Others 15% 58% 5 Source: Soldertec, Second European Lead-free Soldering Roadmap, February 2003 Material Variety Example PWB Finishes Ni/Au, pure tin, Ag PWB Finishes Europe Ni/Au,, SnCu PWB Finishes Japan Don't know 30% Ag 9% Others 9% 6% Pure Tin 12% PdAu 3% NiAu 31% SnCu 12% Others 18% 21% Pure Tin 9% PdAu 3% NiAu 37% 6 Source: Soldertec, Second European Lead-free Soldering Roadmap, February 2003

4 Component Finishes of ICs Company Adv. Micro Devices Agere Agilent Analog Devices Inc. Fujitsu Hitachi IBM Infineon Intel Linear LSI Masushita Semiconductor Leaded NiPdAu, SnCu, SnBi SnBi SnBi, NiPdAu, SnBi, SnCu SnBi SnBi BGA SnBiAg SnAg Cu Company Motorola National Semiconductor NEC Philips Panasonic Sharp Sony Semiconductor ST Microelectronics Samsung Electronics Texas Instruments Toshiba Toyota Leaded NiPdAu SnBi NiPdAu Pd, SnBi, Au SnBi, Pd NiPdAu, SnBi, NiPdAu SnBi NiPdAu SnAg, Pd SnBi SnBi BGA 7 Murata SnNi Source: Prismark, IPC Conference, Web, Company Journals, 2005 Tyco Reliability Solder/Finish Combinations Find your solder/finish combinations! 8 Source: M. Nowottnick, Fraunhofer IZM

5 Processing - Melting Temperatures of Solders SnCu 227 o C 217 o C Lot SnCu (+Ni) SnAg (+Cu) 250 C Application Consumer, Telecommunication Consumer, Telecommunication, Space and Aeronautics, Automotive SnAg + a little Bi (+Cu) Consumer, Telecommunication, Space, SnZn (+Bi) 200 Automotive SnPb 180 o C T = o C SnPb 37 SnBi Current Standard Consumer, Telecommunication Soldering Process Lead-free Solder Risks Reduced solderability (wetting): design, peak temperature Components: popcorn effect, PWB warpage, due to high soldering temperatures: dry storage Higher temperatures: nitrogen atmosphere necessary (reflow or/and wave)? 10

6 Soldering Process - Narrow Process Windows Temperature T Process Window Lead-free Process Window SnPb t soldering Source: M. Nowottnick, Fraunhofer IZM T max T min Time t 11 High melting-points of lead-free solders require new reflow profiles! Soldering Process - Tombstoning Low activation flux Small pads Low solder volume No nitrogen Increase of bridging!? Decreased self-alignment!? Source: M. Nowottnick, Fraunhofer IZM 12

7 Soldering Processes Voiding in Solder Joints voids under a power chip 13 Soldering Process - Voiding Peak temperature 237 C Peak temperature 247 C 14 Source: M. Nowottnick, Fraunhofer IZM Decreasing difference between melting point and max. temperature increases voiding!

8 Equipment Specific Requirements Reflow oven capable to generate and control temperature profile? Solder pot of wave solder oven tolerates lead-free solders? Many companies might want new equipment! Order in time! 15 Equipment Corrosion of Wave Solder Ovens Solution: e. g. coated pump wheels Pump wheels after 6 months use with 16 Source: R. Diehm, SeHo

9 Reliability Adaptation of Tests 17 Material and mechanical properties of lead-free solder joints different: - Adapt reliability tests! - Re-design of PWB, components? Matte and rougher surface of lead-free solder joints: - Revise optical solder joint inspection tests! Whiskers Solder Joint Reliability - Whisker Formation Short cuts possible, in particular in fine pitch applications! Source: Philips CFT Tin whisker on component pin 18

10 Whisker Mechanism on Cu Based Leadframes Irregular growth of intermetallics causes compressive stress in finish Cu 6 Sn 5 Tin Whisker is forced out Sn Finish Cu L/F Whiske r Cu 6 Sn 5 Cu Substrate Source: Philips CFT 19 Countermeasure: Postbake for Cu Leadframes 1 h at 150 C within 24 hours after finishing Higher temperature shifts diffusion from grain boundary to bulk diffusion generating regular intermetallics Diffusion barrier for further intermetallic growth Cu 3 Sn / Cu6Sn5 No whisker! Cu based LF Sn deposit Source: Philips CFT 20

11 Whisker Mechanism on FeNi Lead-Frames 21 Thermal mismatch causes compressive stress! α Sn = ~ 23 ppm/ o α FeNi42 = ~4 ppm/ o Sn ~23 ppm/ o Cu ~17 ppm/ o NiFe42 ~4 ppm/ o Sn FeNi42 Source: Philips CFT Solder Joint Reliability - Standard Whisker Test Standard whisker test not available! Root causes of whiskering are analysed: some models for specific connections (depends on materials in solder and bases) NEMI, E4 (Philips, Infineon, ST Microelectronics, Freescale) and Japanese companies researching on topic Proposals for standard tests under discussion in IEC 22

12 Technical Standards for Production More than 100 standards in electronics production Need adaptation or at least review Mainly IPC, EIA, JEDEC and NEMI push forward standardization Most important standards under review, a few already available for lead-free soldering 23 Source: H. Poschmann, FED Ongoing Implementation Technical Standards Standard Title Status IEC Solderability Test SMD-Components finished 07/2004 IEC series IEC Solderability Test for Leaded applicable Lead-free Components IEC Requirements for lead free solder in pastes (from 03/2002) for high quality inter-connections in preparation electronic assembly. IEC (from 03/2002) Requirements for electronic grade lead free solder alloys and fluxed and nonfluxed lead free solid solder for electronic soldering applications in preparation IEC Component Requirements under discussion 24 Source: H. Poschmann, FED

13 J-STD 020C and following soon D 25 JEDEC J-STD020C : published in July 2004 Encloses 260 C peak temperature profile for small and for thin packages Encloses Floor Life Level Time Conditions Moisture 1 Unlimited <30ºC/85% RH Sensitivity 2 1 year <30ºC/60% RH classes (levels MSL) 2a 3 4 weeks 168 hours <30ºC/60% RH <30ºC/60% RH 4 5 5a 6 72 hours 48 hours 24 hours Time on label <30ºC/60% RH <30ºC/60% RH <30ºC/60% RH <30ºC/60% RH 26 J-STD 020C : Pb Free Process-Package Peak Reflow Temperature classification of packages by body volume and body thickness. Package Thickness < 1.6 mm mm > 2.5 mm Pkg. Volume <350 mm 3 260ºC 260ºC 250ºC Pkg. Volume mm 3 260ºC 250ºC 245ºC Pkg Volume >2000 mm 3 260ºC 245ºC 245ºC Note: Devices shall be process compatible up to and including the stated classification temperature at the rated MSL level. For moisture sensitivity devices using the lowest possible maximum Reflow temperature, which provides proper Reflow of solder, is preferred.

14 JEDEC Standard JESD 22A121 (2005) 27 Management If is Done Prepare Logistics of Items and Information 28

15 Management 6 Weeks Left?! Stocks of Non-Compliant Products S t a r t Components Assembled PWBs Products TIME Your Start with -Compliant Purchasing/Production! July Your Shift to Lead-free Steps to Go (1) Start You remember it was at the end of 2004!?! Management a 3 M Staff training, internal awareness rising, in-housetechnology check a 3 M Contact suppliers and customers: component/material availability, customer requirements... p 3 M Assess new interconnection technology: Soldering, welding, adhesive joining,... a 3 M Decide test criteria: product-related, customer-related, company-specific p 5 M Check and adapt internal logistics: article no. of Pb/Pb-free components, double storage conventional/lead-free components,... p 12 M Qualify solder pastes and wave solders p 12 M Qualify components: finishes, heat-resistance, storage, a additive, p parallel, M month, W week, D day

16 Management Your Shift to Lead-free Steps to Go (2) 31 Total duration 18+ months Finale Furioso July 1, 2006 Lead-free Products p 8 M Qualify PWB: base material (FR 4, CEM, ), finish, heat resistance, warpage, popcorn effects, specific storage conditions,... p 6 M Qualify assembled PWB p 6 M Evaluate and qualify printing and solder oven equipment p 1 M Train staff on process, equipment, repair, testing a 2 W (Order,) Test and allow soldering system a 2 M Delivery of soldering system a 1 W Installation and operation a 1 W Handling training on site a 1 M Test phase for production a 4 M Process optimization a 1 D Handover of system to production Source: Diehm, Seho (modified) Management Joint Industry Approach in Germany - exemplarily Fraunhofer IZM organizes industrial working group leadfree interconnection technology (AK Bleifrei) Approx. 70 participating companies, mainly SMEs 4 meetings annually (since 2000) Sharing experiences, joint tests Supported by technical experts of Fraunhofer IZM 32

17 Management Maybe There is Some Help Somewhere... IPC website on lead-free soldering issues: Arbeitskreis Bleifrei, AK-/ at Fraunhofer IZM Your personal contact at Fraunhofer IZM on / implementation Jutta.Mueller@izm.fraunhofer.de, Tel: Otmar.Deubzer@izm.fraunhofer.de, Tel: Management and There are Some Useful Projects Removal of Hazardous Substances from Electronics - Techniques for SMEs 34

18 Know How to Go Now? Management 35