RoHS Compliant Lead Free PCB Fabrication
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This document discusses strategies for reducing costs in lead-free electronics manufacturing. Direct cost drivers include high-temperature laminates and final finishes, while indirect drivers are increased scrap rates from delamination and pre-baking requirements. The proposed solution is to use mid-grade lead-free capable laminates that offer 15-20% cost savings through lower material costs and moisture absorption with higher reliability. Results show the new laminate meets specifications for decomposition temperature, glass transition temperature, and moisture absorption. HASL is also discussed as a lower-cost alternative to lead-free surface finishes that has benefits like long shelf life and forgiving process windows.
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RoHS Compliant Lead Free PCB Fabrication
- 2. Direct Cost Drivers High Temp Laminates Final Finishes 2
- 3. Indirect Cost Drivers Increased Scrap Rate De-lamination Solderability Pre-Baking Storage / Handling 3
- 4. Section 1 Pb-free Assembly Capable Laminate 4
- 5. IPC 4101/99 /124 from Isola Group/ Insulectro 5
- 6. Current State Audience Poll Common Callouts IS410 / 370HR FR4 RoHS Compliant 180尊C Tg 340尊C Td IPC 4101/126 or /129 6
- 7. Polling Question 7
- 8. Current State (cont.) Audience Poll Effect of Common Callouts 1. Locked in to laminate by brand name 2. Typically Phenolic materials Moisture absorption up to .45% on 0.028 core Less mechanical strength (interlaminate adhesion) More prone to de-lamination during assembly Prone to pad cratering on BGA applications 8
- 9. Current State (cont.) 3. Non-Pb Free capable material FR4 is not capable RoHS Compliant can include standard FR4 180Tg does not guarantee adequate Td 9
- 10. Proposed Solution Mid-Grade Pb-free capable laminates IPC 4101 / 99 (filled) or /124 (unfilled) 150 Tg min. 325 Td min. 10
- 11. Benefits 15-20% Cost Savings on Raw Materials Lower Moisture Absorption (0.10%- 0.25%) Higher interlaminate adhesion Peel strength T-288 >10 minutes Higher Copper to Laminate peel strength 11
- 12. Results (using Isola IS400 as example) 12
- 13. Results Test Group Results Decomposition Temperature Test 1 of 2 Method of Determination: TGA Decomposition Temperature: 331 C Ramp Rate: 10 C/ min Test 2 of 2 Method of Determination: TGA Decomposition Temperature: 334 C Ramp Rate: 10 C/ min 13
- 14. TGA 14
- 15. Results Test Group Results Delta TG Test 1 of 1 Method of Determination: DSC TG Scan 1: 150 C TG Scan 2: 154 C Delta Tg: 4C Ramp Rate: 20 C/min Analysis Method: Half Height 15
- 16. DSC (A) 16
- 17. DSC (B) 17
- 18. Results Test Group Results Time to Decomposition at Temperature Test 1 of 2 Method of Determination: TMA Time to Decomposition: 35.9 minutes Isothermal Temperature: 260 C Test 2 of 2 Method of Determination: TMA Time to Decomposition: 10.4 minutes Isothermal Temperature: 288 C 18
- 19. T-260 19
- 20. T-288 20
- 21. Results Test Group Results Weight Loss % by TGA Test 1 of 1 Percent Weight Loss: 0.2% Start Temperature: 0尊 C Stop Temperature: 0尊 C Comments: Moisture Method % Weight Loss = 0.1717% 21
- 22. Moisture Absorption (A) 22
- 23. Results Test Group Results Peel Strength Condition: Condition A Peel Strength Side 1: 11.73 lbs/in Peel Strength Side 2: 10.95 lbs/in 23
- 24. 6-X Reflow Pb-free Assembly Temperature One board, 3 array One 4.25 x 9.5L, Two 4.75 x 9.5L Thickness + 0.063 TGA moisture = 0.2534% 260属 Peak Temperature 24
- 25. 25
- 26. Results Conditioning As Received Board # 14753-1 Material IS400 Thickness (mil) 0.063 Conveyor Speed (cm/min) 48 Peak Mean Temp (?C) 259.8 TC Temp Range 3.4 Rising time between 150C - 200C 66.67 (sec) Time above 217 101 Time above 255 19.69 Passes to Fail 6x-Pass 26
- 27. Coming Soon FR406HR 27
- 28. Section 2 Pb-Free HASL Audience Poll 28
- 29. Definition SN100CL -this is a SnCu alloy stabilized with Ni, composed of: 99.3% Tin <0.7% Copper 0.05% Nickel 60 ppm Germanium 29
- 30. Industry Misconceptions Predictions of HASLs Demise Solderability Issues Short Duration of Usage 30
- 31. Benefits 1. Lower Copper Erosion on PCB surface and vias 2. Quick Process 3. Long Shelf Life 4. Cost (< 1/14 ENIG) 5. Forgiving a.) Humidity b.) Handling c.) Temperature 6. Solder Joint Strength 31
- 32. Results ( using Florida CirTech HALT example ) Highly Accelerated Life Test 32
- 33. Benefits Solder Joint Strength HALT Test Results 33
- 34. Benefits HALT Test Results 34
- 35. Benefits 35
- 36. Benefits 36
- 37. HALT Test Results Lead-Free HASL, with all different solderpastes pooled together, required the most energy (G-force + thermo-cycling) to break the solder joints. Since this test takes out the failure effect of the components, we can conclude that lead-free HASL solderjoints outperform all other surface finishes, including SnPb HASL. Our thanks go to Tim Murphy of Thomson Lab Services and Florida CirTech for the report abstract. For a full report, please contact James Kelch @ jim@saturnelectronics.com 37
- 38. Drawbacks Not Planar Not Ideal for extremely fine pitch applications Past Solderability Issues HASL and Flow: A Lead-Free Alternative addresses this in the February 08 issue of Request a copy from James Kelch or visit the Lead Free Resource Center on our website. 38
- 39. Drawbacks, cont. Thermal Cycle SN100CL requires a Thermal Cycle in addition to Thermal Cycles in Assembly No Set Industry Standards Neither the IPC nor Nihon Superior had developed a Thickness Acceptability Criteria when SN100CL was introduced Audience Poll 39
- 40. Polling Question 40
- 41. No Standard - Solutions Trigger Event Solderability Issue at Customer 41
- 42. No Standard - Solutions Goal Establish a Set Criteria 42
- 43. Thickness Criteria Generic Thickness Requirement Not proper to have only one Smaller Pads receive thicker solder deposition Solution Minimum Alloy Thickness should be segregated by Ranges of Pad Size 43
- 44. Pad Size (mils) Min. Thickness 126 x 131 50 uin 29 x 83 80 uin 17 x 36 100 uin 44
- 45. Implementation Alloy Control Lower copper content of alloy increases solderability Standard Drossing of solder pot is not enough to keep copper content below 0.90% Recommend a 1/4 - 1/3 solder pot dump once weekly measurement reaches 0.90% 45
- 46. Implementation Specific Design Set-Up Each Design may require its own specific set-up Adjustments Air Knife Pressure Retract Speed Dwell Time 46
- 47. Implementation In effect, since the operating window is smaller than with SnPB,. CONTROL The PROCESS!!! 47
- 48. SN100CL Study Conclusion No Solderability Issues at any customer Fab Notes Fab notes can specify the use of these coupons or range of solder thickness standards Forcing your supplier to meet these specs will give you: 損Control over the Process 48
- 49. Conclusion By implementing one or both of these proposed solutions, you can: Save up to 30% of your bare board cost Increase performance of your products Standardize your fab notes to remove risk of non-performing products Improve your supply base 49
- 50. To view the archived version of this presentation, please email jim@saturnelectronics.com To sign up for our upcoming Lead Free Newsletter, please email jay@saturnelectronics.com 50
- 51. Thank You! Saturn Electronics Corporation would like to thank our presenters: Dave Coppens / Isola Terry Staskowicz / Insulectro Glenn Sikorcin / Florida CirTech *Dont forget to visit the Lead Free Resource Center 51