ACEA/JAMA/KAMA/CLEPA/ et. al. request the exemption of: Lead in high melting temperature solder with lead content > 80%

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1 No. Criteria 1 Wording of the exemption Materials and components: 1. Lead in high melting temperature solder i.e. lead based solder alloys containing above 80% by weight of lead. Scope and expiry date of the exemption 2. No expiry date can be defined until a technical solution is determined. Review after What is the application in which the substance/compound is used for and what is its specific technical function? 1. Electrical Interconnections (see Annex 1 Figure 1) High melting point lead containing solders are used to form high reliability internal connections in electronic components, which is particularly important considering higher lead-free processing temperatures. 2. Die Attach (see Annex 1 Figure 2) High melting point lead containing solders are also used as a die attach for power devices and discrete semiconductors providing both a high conductive thermal interface and a reliable electrical interface. 3. Hermetic Sealing (see Annex 1 Figure 3) High melting point lead containing solders are used as a substance for hermetic sealing. 4. Plastic Over-moulding (see Annex 1 Figure 4) High temperature plastic over-moulding (>220 deg C) requires high lead containing solder for component attachment, which is required to withstand the higher temperatures of the moulding process. Page 1 of 24

2 5. Ceramic BGA (see Annex 1 Figure 5) Ceramic BGAs require high melting point lead containing solder balls for electrical connection. 6. High Power Applications (see Annex 2 Figure 6) High power applications require high melting point lead-containing solder to maintain internal electrical integrity due to internal power dissipation. Automotive applications using such electrical applications are, for instance, starters, alternators, converters, electrical assisted steering, engines & gearboxes computer-control devices, electrical brakes, ABS & ESP systems, etc. 3 What is the specific (technical) function of the substance/compound in this application? 1. Electrical Interconnection For high reliability internal connections in electronic components, the melting point of the solder must be higher than the reflow temperature for lead-free assembly (up to 260 deg C). 2. Die Attach In die attach applications, high stress is generated due to the increase in junction temperature, die size and Coefficient of Thermal Expansion (CTE) mismatch between component materials. There is also the need to avoid solder remelt during process as in above electrical connectivity. The solder must have low modulus of elasticity to withstand a high number of thermal fatigue cycles required in automotive applications. The die attach is also required to possess high thermal conductivity since power and semiconductor devices generate significant levels of Page 2 of 24

3 heat. 3. Hermetic Sealing Solder used as a sealing substance between ceramic and metal must withstand the high processing temperatures and accommodate the CTE mismatch between the lid and base as well as providing hermetic sealing so as not to impair the performance of the device, e.g. crystal oscillators and sensors. 4. Plastic Over-moulding The solder used for attaching components on electronic circuit boards must have sufficient strength to withstand the high temperatures generated during plastic over-moulding of that electronic assembly. 5. Ceramic BGA Solder balls for ceramic BGAs use high melting point lead containing solder in order to maintain a high stand-off height which improves the thermal fatigue robustness by providing compliance between the device and substrate. 6. High Power Applications High power applications generate heat during use and require high melting point lead-containing solder to prevent the internal interconnections melting during operation, e.g. generator/alternator diodes to rectify the current for board net must survive temperature of 280 deg C. Therefore the melting point of solder must be higher than 280 deg C. Diode will be short-circuited if melting point of solder is exceeded (see Annex 2 Figure 7). Page 3 of 24

4 4 Please justify why this application falls under the scope of the ELV or the RoHS Directive (e.g. is it a finished product? is it a fixed installation? What category of the WEEE Directive does it belong to?). With reference to ELV Annex II item 8(a) Solder in electronic circuit boards and other electrical applications except on glass, all items previously listed above fall under this category. Many of these components are shared between the automotive and non-automotive industry and are covered by RoHS Directive for consumer electronics applications. High melting point lead containing solders are exempt within the RoHS Directive. Automotive electronics are not covered by the WEEE or RoHS Directive. 5 What is the amount (in absolute number and in percentage by weight) of the substance/compound in: i) the homogeneous material ii) the application and iii) total EU annually for relevant applications? 1. Homogenous material: percentage of lead by weight used in the solder Internal connections: 85% *) Die attach: 90% Sealing: 85% Over-moulding: 90% Ceramic BGAs: 90%. *) The soldering process will however result in some blending of the original solder alloy with the solder alloy used for component attach, resulting in regions of alloy that could fall below 85% lead content. 2. Applications The majority of high powered components are found in steering, braking and powertrain electronic control units (ECU). Nearly all automotive electronics Page 4 of 24

5 products contain components utilizing high lead solder. Assuming the amount of lead used in solder in the above applications is ~ 0.003g per component, then typical automotive ECU s would contain: For Braking ECU approximately 30 affected parts For Steering ECU approximately 20 parts For Powertrain ECU approximately 40 affected parts For Power Management (Generator Diodes) approximately 9 affected parts & other ECU s within the vehicle about 20 parts This equates to: For Braking ECU 0.09g/vehicle For Steering ECU 0.06g/vehicle For Powertrain ECU 0.12g/vehicle For Power Management (Generator Diodes) 0.14g/vehicle & other ECU s (e.g. body control modules, climate control, seat memory, roof modules, etc.) 0.06g/vehicle. 3. Total EU Annual Amount Assuming 16 million vehicles registered per year (ref: ACEA 2007, EU27 + EFTA), then the total amount of lead is 16 million x 0.47g = 7,5 tonne per year. 6 Please justify your contribution according to Article 4 (2) (b) (ii) ELV There is no known alternative to the high melting point solder containing greater than 80% lead in the applications Page 5 of 24

6 or according to Article 5 (1) (b) RoHS Directive whereas: listed above. It is therefore necessary to apply for an exemption for high melting point lead-containing solder in relation to entry 8a of Annex II to the ELV 2000/53/EC. 7 Justification according to technical and scientific progress; 1. Electrical Interconnections For electrical interconnections, the solder must have a melting point in excess of 260 deg C to maintain integrity of the interconnection during board assembly and subsequent operation. It must combine with the plating to form an intermetallic compound which will retain some ductility during operational life. The solder must also have fatigue resistant properties to withstand the thermal excursions and vibrational stress found in an automotive environment. To meet the processing and mechanical requirements requires a unique combination of material properties such as melting point, CTE, modulus of elasticity, tensile and shear strength and elongation. Currently there is no commercially lead-free material substitute available. (see Annex 3 Figure 8). 2. Die Attach For die attach the properties required are also unique. In an automotive environment the ambient temperature can be in excess of 125 deg C and in order to maintain product reliability over years, the junction temperature of the silicon die must not exceed 150 deg C (175 deg C for some specific power components). During operation the die temperature rises due to the power dissipation. In order to minimise the temperature increase, a high thermally conductive material is required. Stress is also generated due to the CTE mismatch between the silicon die and copper Page 6 of 24

7 heat slug/leadframe. If excessive stress is generated, de-lamination will occur resulting in a decrease in thermal performance, die fracture, and possible movement of the die causing wire bond failure. 3. Hermetic Sealing Solders used for hermetic sealing must withstand processing temperatures of 260 deg C. They must form an intermetallic compound with the base and lid resulting in a solder joint which is not brittle and has sufficient ductility to accommodate the CTE between base and lid. 4. Plastic Over-moulding The components are attached to the printed circuit board (PCB) and then over-moulded. The solder joints must have sufficient strength above 220 deg C to withstand the temperature and force generated due to the moulding process. The assembly must then be reliable in a harsh automotive environment over the life of the product. 5. Ceramic BGA Lead-free solders are used in ceramic BGAs in order to maintain the solder stand-off joint. The strain generated within the solder joint is inversely proportional to the solder joint height. Increasing the solder joint height decreases the strain and increases the fatigue life. Ceramic BGAs have a large CTE mismatch between the board and BGA. In order to fulfil automotive requirements, the strain has to be minimised. High lead solder does not collapse like a Page 7 of 24

8 SAC lead-free solder during processing and therefore the solder joint stand-off height is maintained. 6. High Power Applications For generator diodes low temperature silver sintering is under laboratory scale investigation but first results show problems due to the brittle silver interface. Also the simultaneous connection on both sides of the diode showed to be very difficult. Laboratory solutions are not expected in the near future. 8 Substitution of concerned hazardous substances via materials and components not containing these is technically or scientifically either practicable or impracticable; For long life reliability no other material (than high temperature lead containing solder) has been found with the unique combination of melting point, mechanical, thermal, electrical and chemical properties. See Annex 3 Figures 8 and 9. Tin, Silver and Copper SAC Alloys These lead-free solder alloys are based on Tin, Silver and Copper and are the solders most commonly used in lead-free board assembly. If SAC alloys were used for die attach, internal connection, and sealing they would lose strength and become pasty during the board assembly process resulting in movement and reduced reliability. Other solder systems with low melting points exist, Tin Gold System (SnAu80) The melting point is 280 deg C which would be acceptable in terms of processing, but SnAu forms a brittle intermetallic compound which would result in poor thermal fatigue and mechanical shock Page 8 of 24

9 performance resulting in a reliability hazard. Other solder systems exist with a higher melting point but could result in component issues. Electrical Conductive Adhesives These will be acceptable for addressing process thermal excursions, however they have a poor thermal conductivity compared with solder which would make them unacceptable for die attach and internal connectivity including BGAs. They would also not form a hermetic seal which would be unacceptable for sealing applications. Solder alloy with high lead content stays solid up to : 235 deg C for a 85% lead content alloy 270 deg C for a 90% lead content alloy 385 deg C for a 95% lead content alloy When above those temperature levels, the alloy becomes pasty and so looses its mechanical properties. 9 Elimination or substitution of concerned hazardous substances via design changes is technically or scientifically either practicable or impracticable; 1. & 2. Electrical Interconnection & Die Attach Automotive electronics are used in harsh environments often in an enclosed environment where convection cooling is not an option. They are used in safety applications and are expected to have year lifetime. Automotive electronics also have to be commercially viable. Expensive thermal management techniques are not commercially viable. During the life of the product, the electrical interface connection and die attach are subject to wide range of temperature, vibration and humidity. To replace the Page 9 of 24

10 high temperature solder would require a dramatic reduction in the internal solder joint stress. This can only be achieved by the use of new component packaging materials which would require extensive characterization and validation to ensure long term reliability. 3. Hermetic Sealing Hermetic sealing requires a material that can be applied at sufficiently low temperature so as not to overstress the internal device. This has to be commercially viable which rules out alternative hermetic sealing methods. 4. Plastic Over-moulding High temperature solders do exist that would give sufficient strength during the over-moulding process. They would however not meet the reliability requirements without a change in the materials (see question 9 section 1 and 2). 5. Ceramic BGA Ceramic BGAs would require a reduction in the stress generated which would require a material change (see question 9 section 1 and 2). 6. High Power Applications (Generator Diodes) This would require design change which is not possible within the given timeframes of ELV Annex II. 10 Negative environmental, health and/or consumer safety impacts caused by There are no alternative substitutes for the use of high temperature lead-containing solder in the application Page 10 of 24

11 substitution are either likely or unlikely to outweigh environmental, health and/or consumer safety benefits thereof (If existing, please refer to relevant studies on negative or positive impacts caused by substitution). examples already provided. Many of the high performance / high reliability applications that use high-lead solders require exacting performance characteristics because there is significant risk to human life / safety. Low reliability substitutions in these systems would result in increased human mortality. 11 Please provide sound data/evidence on why substitution / elimination is either practicable or impracticable (e.g. what research has been done, what was the outcome, is there a timeline for possible substitutes, why is the substance and its function in the application indispensable or not, is there available economic data on the possible substitutes, where relevant, etc.). Thermal fluctuations during normal operations cause strain to be generated due to differences in thermal coefficient expansion within the assembly. Thermal fluctuations can be produced by heat being dissipated or by environmental temperature changes. Repetition will produce cyclic strain which will cause the solder joint to fail through fatigue. The reliability of the solder joint will depend upon the alloys resistance to fatigue, and the magnitude of the strain generated. The strain generated due to CTE mismatch can be simply approximated to;- where ΔT is the temperature excursion, dependent upon the power dissipation and the change from minimummaximum operating temperature, Δα is the difference between CTE or the substrate and the component chip, Dnp is the distance from neutral point - the larger the die Page 11 of 24

12 or packaged component, the greater the strain generated. t is the solder joint height. The larger the solder joint height, the less strain is generated. The fatigue life a solder joint can be approximated by Coffin - Manson equation N f = C p -n Where N f is the number of thermal fatigue cycles to failure, C and n are material constants and p is the strain generated. The smaller the strain, the greater the fatigue life. This equation has been modified by Engelmair and others to take into account material properties and the reduction in strain due to compliance within the joint. Automotive electronics differs from that in consumer applications in that the desired number of cycles N f is much larger, and the environment is much harsher. Consumer Automotive Life 3-5 years Up to 15 years Environment 0-40ºC -40º to 125/155ºC There are basically two types of solder, soft solders based on Sn-Pb, lead, tin, indium alloys; and hard solders based on gold eutectics such as Au-Sn, Au-Ge. Die attach and applications which require some ductility within the joint have to use soft solders, which transmit very little stress to the die, ceramic body, but will degrade due to thermal fatigue during temperature or power cycling. Page 12 of 24

13 Annex 3 Figure 8 and 9 show that there are no soft solder alternatives which have appropriate melting points. Hard solders based on Au-Sn do not usually degrade by fatigue due to the high mechanical strength. Ceramic and silicon die are brittle materials and will crack if they are subjected to any tensile or torsional stress, resulting in lower product reliability. High temperature solder is used as a die attachment (silicon to copper alloy) or as a lid seal (e.g. Analogue Sensor packaged in a CLCC (ceramic body, steel lid). The CTE mismatch will exert considerable stress on the die, ceramic body and may fracture in some cases. As an example, new generation stop-start systems under development require the use of high melting point lead containing solder because of new higher constraints, such as electric current circulation up to 50ms@1000A + 600ms@600A + permanent 150A in combination with an increase of thermal environment up to 170 deg C. Tests performed with six types of lead free solders show a drastic decrease of number of cycles to failure, and so an unaccepted level of reliability. Please see Annex 4 for reliability information and semiconductor manufacturer Input. Please see Annex 5 for SAE publication, which includes Weibull life prediction calculations and examples of the number of power cycles to failure for both high melting point lead containing solders and lead free solders. 12 Please also indicate if feasible substitutes currently exist in an industrial and/or commercial scale for A current substitution of high melting point lead containing solder is not possible. Research and development is being carried out by semi- Page 13 of 24

14 similar use. 13 Please indicate the possibilities and/or the status for the development of substitutes and indicate if these substitutes were available by 1 July 2003 (ELV) or by 1 July 2006 (RoHS) or at a later stage. conductor suppliers. Nothing exists in the industrial and consumer sectors. No substitution for the replacement of high melting point lead containing solder currently exists for the automotive applications listed under question Please indicate if any current restrictions apply to such substitutes. If yes, please quote the exact title of the appropriate legislation/regulation. 15 Please indicate benefits / advantages and disadvantages of such substitutes. 16 Please state whether there are overlapping issues with other relevant legislation such as e.g. the Energy-using Products (EuP) - EuP Directive (2005/32/EC) that should be taken into account. Since there are no suitable substitutes, this question is not applicable. No substitutes exist, therefore this question is not applicable. There is no overlap in terms of the ELV and RoHS legislation as such but there is a technical overlap. Electronic components used within the framework of RoHS are the same as those used under ELV e.g. ICs, components with internal connections etc. 17 If a transition period between the publication of an amended exemption is needed or seems appropriate, please state how long this period should be for the specific application concerned. When a suitable alternative has been identified and approved, process optimisation and qualification by semiconductor manufacturers (2-3 years). Semiconductor manufacturers will then need to transition to the new alternative materials, when developed, before components become widely available (1-2 years). Components will then need to be qualified at the module Page 14 of 24

15 level before they can be installed in Automotive safety critical applications (2-3 years) A transition period 5-8 years will be required once a suitable alternative has been identified. This transition will be for the first set of new products, with more time required to acquire high volume reliability data for remaining products. Please see Annex 6 for timescales. Page 15 of 24

16 ANNEX 1: Components Affected Examples of Cross Section Components Affected containing high temperature lead containing solder 1. Internal Connections Figure 1: Leaded Capacitor representative example component 2. Die Attach Figure 2: Power Semiconductor - representative example component Page 16 of 24

17 3. Hermetic sealing Metal lid High melting- type solder used for seal between ceramic and lid in ceramic leadless chip carrier e.g. sensors Ceramic body Figure 3: Ceramic Leadless Chip Carrier representative example component 4. Plastic Overmoulding PCB assembly overmoulding High melting-type solder used to attach components to circuit board Figure 4: Example Overmoulded Component 5. Ceramic Ball Grid Array (CBGA) High melting type solder used for solder balls Figure 5: Ceramic Ball Grid Array - representative example component Page 17 of 24

18 Annex 2: High Power Applications HT Solder layers Figure 6: Generator Diode Figure 7: Graph showing junction temperature during load dump Page 18 of 24

19 MeltingTemperature ACEA/JAMA/KAMA/CLEPA/ et. al. request the exemption of: Annex 3: High Temperature Lead Containing Solder & Candidates for Substitution Lead containing solder Zn-Al Lead-free solder 350 deg C Sn-high Sb 300 deg C High temperaturehigh lead solder Au-Sn BI system 250 deg C Sn-Cu Sn-low Sb 200 deg C Sn37Pb Sn-Ag-Cu Sn-Zn (Bi) Sn-Ag-Cu-Bi 150 deg C Figure 8: High Temperature Solder Alternatives Solder Type Alloy Melting Point ºC Comments on Unsuitability Sn-Zn (Bi) Sn 8Zn 3Bi Sn-Ag-Cu-Bi Sn 2.5Ag 1Bi 0.5Cu Melting point is too low Sn-Ag-Cu Sn 3Ag 0.5Cu Sn-Cu Sn 0.7Cu 227 Sn-low Sb Sn 5Sb Bi systems Bi 2.5Ag 263 Melting temperature only slightly higher than SAC Low Ductility, Low Strength Au-Sn Au 20Sn 280 Low Ductility, Negative environmental impact due to being Au based Sn-high Sb Sn >43Sb 325->420 Melting point too high Zn-Al Zn (4-6)Al (Ga,Ge<Mg) Figure 9: High Temperature Solder Alternatives Page 19 of 24

20 Annex 4: Reliability Information and Semiconductor Manufacturer Input Figure 10: IBM Position On RoHS exemption 7a Lead (Pb ) in High Melting Temperature Solder and ELV exemption 8a- Lead in solder in electronic circuit boards and other electrical applications except on glass Page 20 of 24

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23 Annex 5: SAE Publication & Extract from Valeo Study Example of relevant study: SAE publication N "Innovative Power Packaging for Demanding Automotive Power Electronics" by Jean-Michel Morelle & Julien Pfiffer, which notably includes Weibull calculations And an extract from a Valeo Electronique study, also with numbers of power cycles to failure (where high lead solder means high melting point lead containing solder) "Inverters and converters for powertrain systems are at stake in the context of lead-free and RoHS compliant electronics. The stringent environment conditions of these powertrain systems are inducing, to the power dice of the power modules, high average working temperatures with superimposed high amplitude temperature swings. This particular situation brings the need for high temperature and highly compliant solders for the power die assembly. Lead-free solder systems are none conformal and did exhibit poor reliability under power cycling testing. Table 1 is a comparison of high-lead and lead-free solder systems when tested according to powertrain representative constrains." Page 23 of 24

24 ACEA/JAMA/KAMA/CLEPA/ et. al. request the exemption of: Annex 6: Automotive Time-scale for Transition to Replacement of High Temperature Lead Containing Solder Once an Alternative is Identified GENERIC OEM DEVELOPMENT CYCLE - APPROX MONTHS. Month Program Start Confirm Strategy / Set targets Strategy Confirmation /Target setting: Decisions on Archtecture made. New vs. Carry-over content Identified. Resource / Budget for Programme Delivery finalised. NO SCOPE FOR PROGRAMME CHANGE AFTER THIS CHECKPOINT. Supplier Selection Pre-work - skills recruiting, learning from current pb-free technologies Design - scope technologies, complexity, packaging, integration, component sourcing Manufacturing Trials & Prototype builds Manufacturing Trials: Component Compatibility due to differences in temperature. Revalidation of Process Parameters - due to narrower processing window. Process changes - e.g. flux changes, solder pot modifications. Oven Capability / power consumption. Visual Inspection Validation - New Processes to be developed / adoted - technicians re-trained. Validation - (prototype & Production). VALIDATION: Temperature cycling (-55 C / 120 C) cycles Temperature storage (63 C / 93% RH) hours. Vibration Thermal Shock Mechanical Shock Drop Tests Humidity cycling (-10 C / +65 C; 80 to 96% RH) Terminal pull-out forces Power Temperature Cycling System Integration / complexity resolution Inspection (after above tests): Scanning Acoustic Microscopy (SAM) for delamination issues. Visual inspection (40-300x) - pop corning / solder balls, cracking, delamination, rest of flux, PCB warpage, whisker growth, wetting, contact angles, corrosion. Metallographic analysis of solder joints Leakage current during Humidity Cycling Concern - current data is relevant to requirements of consumer elctronics NOT to the greater requirements of automotive applications. Total Programme: months Page 24 of 24