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Page 1 Flammability Assurance for Printed Wiring Boards Certification by Similarity Analysis Proposal Boeing Commercial Airplanes Group PWB Material Working.

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Presentation on theme: "Page 1 Flammability Assurance for Printed Wiring Boards Certification by Similarity Analysis Proposal Boeing Commercial Airplanes Group PWB Material Working."— Presentation transcript:

1 Page 1 Flammability Assurance for Printed Wiring Boards Certification by Similarity Analysis Proposal Boeing Commercial Airplanes Group PWB Material Working Group June, 2003

2 Page 2 Test Results Summary Background on PWB Working Group Task Working Group/Test Plan Objectives Test Results Data Interpretation Proposed Certification by Similarity Process Recommendations Agenda

3 Page 3 Test Results Summary Data shows certification of PWBs by similarity is a valid process –Investigated IPC * /21 and /24 laminates, and IPC-CC-830 conformal coatings meeting IPC-TM-650 or UL-94 V0 flammability requirements No factors showed significant effect on PWB FAR flammability –Laminate materials not a significant factor for /21 and /24 bare PWBs Thickness, layer count, PWB fabricator (fabrication process), and laminate manufacturer had minimal effect –Adding conformal coating not a significant factor for /21 and /24 laminates Acrylic, urethane, and silicone conformal coatings all showed minimal effect on extinguishing time and burn length All conformal coated PWBs met FAR 25 requirements by large margin * The Institute for Interconnecting and Packaging Electronic Circuits

4 Page 4 PWB Working Group – Project Background FAA IMFTWG Subgroup was established to evaluate flammability certification alternatives to FAR 12 second vertical flammability test for each PWB part number –Testing by individual part number is inefficient and expensive –Baseline testing and establishing acceptable PWB industry specifications and process control provides better assurance –Showing compliance by material similarity is a significant need for aerospace electronics FAA Seattle Aircraft Certification Office is involved in process and test plan development

5 Page 5 Flammability Test Plan Objectives Develop baseline FAR 25 flammability certification data for PWBs from IPC-4101 /21 and /24 resin families laminates and conformal coatings from IPC-CC-830 acrylic, urethane, and silicone material families PWB laminates meet IPC-4101 flammability requirements IPC-TM-650 (flammability) test method , or UL-94 V0 Conformal coatings meet IPC-CC-830 plus UL-94 V0 Validate that PWBs show similarity to previously tested materials contingent on meeting above criteria

6 Page 6 Flammability Test Plan Objectives Classify and test PWBs according to IPC-4101 data sheets (resin types) –Test Plan Variables Test various thicknesses of PWBs from each resin system Test PWBs from several different pwb fabricators Test PWBs fabricated from different laminate manufactures

7 Page 7 Flammability Test Plan Objectives Classify and test conformal coatings according to IPC-CC-830 material families Three types of conformal coatings were included AR = Acrylic – Humiseal 1H71 UR = Urethane – Dymax 984 LVUF SR = Silicone – Humiseal 1C53 All coatings carry a UL-94 V0 flame rating

8 Page 8 Test Summary 82 Production PWBs tested –Full FAA Conformity appropriate for certification data PWBs fabricated from the two major IPC 4101 resin families used in PWB fabrication today –Low temp epoxy /21, high temp epoxy /24 PWBs manufactured by four different PWB fabricators –Viasystems, Tyco, Holaday Circuits, Cosmotronics PWBs fabricated from IPC-4101 laminates from 4 different manufacturers –Nelco, Double Treat, Polyclad, Isola Both bare and conformal coated PWBs were tested –Acrylic, urethane, and silicone conformal coatings meeting IPC-CC-830 and UL-94 V0 –Acrylic, urethane, and silicone

9 Page 9 Background on the Resin Systems PWB Speci- fication Sheet # Re- inforcement Resin SystemID ReferenceGlass Transition Range Industry Flammability Testing IPC-4101 /21 WOVEN E-GLASS FABRIC Epoxy, Flame Resistant NEMA FR-4, MIL-S /04 – GF, GFN, GFK 110°C Minimum IPC-TM per IPC Monthly samples at the laminate level lPC-4101 /24 WOVEN E-GLASS FABRIC Majority Epoxy Modified or Unmodified, Flame Resistant NEMA FR-4, MIL-S /04 – GF, GFG 150°C - 200°C IPC-TM per IPC Monthly samples at the laminate level

10 Page 10 Background on the three conformal coatings Conformal Coat Description/Classification Flammability Rating Type AR (Acrylic) per IPC-CC-830 Humiseal UL-94 V0 Type UR (Urethane) per IPC-CC-830 Dymax 984 LVUF UL-94 V0 Type SR (Silicone) per IPC-CC-830 Humiseal 1C53 UL-94 V0

11 Page 11 Bare PWB Test Results *Testing Performed by FAA at FAA Tech Center

12 Page 12 Conformally Coated PWB Test Results

13 Page 13 Burn Length Examples

14 Page 14 Burn Length Examples 12 sec vertical Zero burn length 12 sec vertical 0.1 burn length 60 sec vertical 1 burn length

15 Page 15 Test Results Summary Data shows certification of PWBs by similarity is a valid process –Investigated IPC * /21 and /24 laminates, and IPC-CC-830 conformal coatings meeting IPC-TM-650 or UL-94 V0 flammability requirements No factors showed significant effect on PWB FAR flammability –Laminate materials not a significant factor for /21 and /24 bare PWBs Thickness, layer count, PWB fabricator (fabrication process), and laminate manufacturer had minimal effect –Adding conformal coating not a significant factor for /21 and /24 laminates Acrylic, urethane, and silicone conformal coatings all showed minimal effect on extinguishing time and burn length All conformal coated PWBs met FAR 25 requirements by large margin * The Institute for Interconnecting and Packaging Electronic Circuits

16 Page 16 Proposed Criteria for Flammability Certification of PWBs by Similarity FAR 25 flammability certification of Printed Wiring Boards PWBs by similarity to previously tested materials would be acceptable based upon the following processes and criteria: –Industry specifications are used to group the PWBs into material families. Certification by similarity would be limited to materials with the following criteria; 1)PWBs claiming similarity must be manufactured in compliance with the same IPC-4101 laminate specification sheets (i.e. from the same resin family) for which FAR 25 certification data exists. 2)PWBs must be constructed only from laminates according to IPC-4101 specification sheets that either include a required IPC flammability test as a laminate test, or include the flammability test as a PWB drawing requirement test via UL 94 and carry a V0 flame rating. 3) Conformal coating used on the PWB must be IPC-CC-830 compliant and carry a UL-94 VO flame rating. –PWB certification data is established per FAR (12-sec vertical). Another PWB part number may claim similarity to the original certification test data if the PWB satisfies the above criteria.

17 Page 17 Proposed Certification by Similarity Process Flow Conformal coating registered & tested UL 94 V0 ? NO YES NO FAR 25 Flame Test NO YES Flame Test Report Design for a PWB YES PWB Laminates registered & tested per IPC 4101* or UL 94- V0? Flammability Assured Similarity to Documented test results Is PWB registered & tested per UL 94- V0? ** * Requirement IPC Test Method TM 650 for flammability ** Far 25 Certification data must exist for similar pwb constructed of similar laminate

18 Page 18 Recommendations Short Term Recommendations –Formal Memo of Agreement between Boeing and FAA to allow implementation of proposed PWB Certification by Similarity Process Based upon released requirements document Mid/Long Range Recommendations –FAA IMFTWG PWB sub-group to document PWB certification by similarity process for inclusion in appropriate FAA documentation (Fire Test Handbook, AC, ?)


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