inemi Statement of Work (SOW) Board Assembly TIG Strain Guidance for PCBAs

Transcription

1 inemi Statement of Work (SOW) Board Assembly TIG Strain Guidance for PCBAs Version #1.7 Date: March 7, Project Leader: Jagadeesh Radhakrishnan (Intel) Co-Project Leaders: Anurag Bansal (Cisco), Matt Kelly (IBM) inemi Coach: David Godlewski Basic Project Information The IPC9704 standard was revised February (now IPC9704A) to encompass the impact of Pb-free electronics and to incorporate consistent strain gage placement / measurement techniques to monitor printed circuit board assembly (PCBA) fleure within a manufacturing environment. With the intent of making IPC9704A strictly a methodology document, appendices A and B that were present in original IPC9704 documentation were removed. These appendices are very important. They outline strain limits and provide reference for rate limited strain guidance for eutectic solder. New Pb-free content additions within these appendices are intended to form the basis of a new white paper guidance document. The legacy SnPb guidance will be maintained in the white paper. The benefit of this new approach is to ensure that new Pb-free strain limiting guidance can be more easily updated in a timely manner, as new information becomes available. This project team is being formed to develop such a white paper, within the scope defined below. Scope of Work The scope of the project is shown in the project IS / IS Not Analysis table: Project Is / Is Not Analysis This Project IS: This Project IS NOT: Strain Guidance for PCBAs Intended to encompass various Pb-free technologies and materials SnAgCu based alloys, laminates, PCB thickness Intended to provide manufacturing strain guidance for Pbfree BGA only (by package attributes BGA pitch, package body side and package type along with pad design) based on eisting data collection Intended to make recommendation for further testing, if necessary, based on eisting data collection Recommendations will be provided to the IPC/JEDEC committee for further industry review and feedback/comments Development of a specific standard(s) Intended to include packages such as FC-QFNs, LGA hybrid sockets, SMT DIMMs, mezzanine SMT connectors, SMT mounted voltage regulators, and other packages of interest. Instead, these will be listed as recommended future work Intended to replace component supplier or customer guidance Intended to repeat prior work on SnPb solder alloys Intended for future updates to the white paper. Such an effort would require a new SOW, managed by IPC/JEDEC NOTE: All changes to SOW must be approved by the TC (version control) Page 1 of 5 Strain Guidance for PCBAs, Version #1.7, March 7,

2 This Project IS: Develop BGA strain guidance will apply to primary attach and rework manufacturing process operations This Project IS NOT: Intended to include card level design features (such as mirrored BGA structures vs. single-sided BGA interconnects) Intended to include card level mechanical hardware interactions (such as Ganged or single heatsink structures or other mechanical assembly operations) The white paper will be presented to the IPC/JEDEC committee for further industry review and feedback/comments. The publication and ongoing management of the white paper will be handled by IPC/JEDEC. It would be beneficial to have key members of the inemi whitepaper group continue involvement in the IPC/JEDEC committee to ensure continuity of data and recommendations. Approach & Core Activities The approach and steps that will be undertaken: Project planning & team(s) formation: ID eactly what work will be done and by whom with schedules Phase 1: Eisting data sharing and discussions by participating firms Phase 2: Compilation and analysis of shared data Phase 3: New limit definitions Phase 4: Gap analysis and additional work identification Technical Focus Elements PCB laminate materials (standard loss and low loss materials, organic FR4 and Ceramic) Card stack-up / thickness variation BGA component package constructions Learnings on SMT chip capacitors PCB and component package surface finish SnAgCu alloy assembly & rework performance Strain rate that was used to collect the data Multiple fleure eposures Epected Deliverables 1. Pb-free vs. SnPb failure mode differences: discuss new failure mode(s) determining new strain limits 2. Inclusion of legacy SnPb strain limits 3. Strain limit guidance for BGAs using Pb-free solders (specific alloys with supporting data) 4. Etrapolation of strain limitations for card materials and thicknesses ranging from to Define a process for updating whitepaper 6. Define test methodology for future work data generation Dependency This work is predicated on the assumption that there are sufficient data available in the industry to make the decisions required within the scope of this project. If it is found during the course of this project that additional data is required, this Statement of Work may be modified to include a test phase. Any such revised SOW would be submitted to the inemi Technical Committee for approval prior to committing the project team to the tasks identified in the revised SOW. NOTE: All changes to SOW must be approved by the TC (version control) Page 2 of 5 Strain Guidance for PCBAs, Version #1.7, March 7,

3 Any future updates to the whitepaper is outside the scope of this project; therefore, these updates will necessitate the formation of another inemi project group or through an IPC taskforce. Purpose of Project The purpose of this project is: Intended to provide manufacturing strain guidance in absence of component and/or customer supplier guidance. Clarify quantitative vs. qualitative assessment. Qualitative assessment would involve manufacturing processes such as heatsink loading that have different loading or boundary conditions from IPC9707 type testing that was used to generate component guidance. Set up a process for updating the white paper document on a timely basis the current project is not intended to be static development that can be used indefinitely without further updates and input from the general semiconductor industry. Define/Distinguish test methodology (such as IPC9702/IPC9707), failure mode, use of modeling data used to generate guidance. Return on Investment This project proposes to justify the changes to the current standard listed above by demonstrating a tangible return on investment. Criteria: Impact if work is not done o No strain guidance is available when there is no component or customer supplied guidance o Possible over-engineering of products, resulting in overspend o Possible inaccurate or inconsistent results from strain gage testing with current methodology o Possible solder joint interconnect latent failures going out of the manufacturing line o Eliminate conflicts/confusion with other IPC standards (i.e. IPC/JEDEC-9707) o Adapts to changes in technology there is no need to change the IPC9704A standard o Supports new material restrictions leading to higher susceptibility to fleure induced failure o Cost, quality, yield, efficiency gained, process and/or test time, quicker diagnoses of issues, other resource savings, prevention of class failures in the field Previous Related Work IPC/JEDEC-9704A: Printed Wiring Board (PWB) Strain Gage Test Guideline (Estimated release - February ) Describes how to perform strain gage testing for PWBs in the board manufacturing process Address the importance of using a consistent strain gage placement (along package diagonal) to properly assess risk Update the document to reflect new PWB strain guidance related to Pb-free technology Discuss and incorporate best practices from eperienced IPC/JEDEC-9704 users (especially when it is hard to follow the recommended gage placement; e.g., cutting package corners or new strain gage technologies) Challenges: o This standard allows for multiple gage placement layouts, leading to ambiguity in data interpretation, since measurements cannot be directly compared between different gage placements o Maimum allowable strain is defined for tin-lead PCBAs only (see IPC9704 Appendi A) o Maimum allowable strain is based on principal strain measurements, which require consideration of the angle of maimum strain for proper risk assessment or dictate that much more conservative limits be used o Criteria for defining a strain limit vary with different component, board, and strain rate parameters NOTE: All changes to SOW must be approved by the TC (version control) Page 3 of 5 Strain Guidance for PCBAs, Version #1.7, March 7,

4 Prospective Participants Semiconductor manufacturers Original equipment manufacturers Contract manufacturers Other: Reliability engineers, manufacturing engineers, test engineers, research and development, quality assurance, procurement, standards bodies Project team members are epected to participate by sharing knowledge on board fleure and FA methods. The team will draft a recommendation for the IPC/JEDEC committee on proposed changes to the current standard. (listed firms in alphabetical order) Agilent Technologies Celestica Cisco Systems Inc. Dell Delphi Fletronics Foconn Hewlett-Packard Company IBM Corporation Intel Corporation IPC IST - Integrated Service Technology, Inc. Lenovo National Instruments Pleus Quanta Computer Sanmina-SCI Corporation Stress Engineering Services Stress Investigators Engineering Inc. Teradyne Inc. Test Research Inc. Vishay Vitronics-Soltec Project Plan For this phase of work recommended not to include additional testing; consider this eercise as data collection, sharing, and new BGA limitation guidance only. Schedule with Milestones Tasks 1Q 2Q 3Q 4Q Task 1 Define scope / boundaries, approach & methodology Task 2 Research available information, tools, methodologies, approaches April May June July Aug Task 3 Compile data bases Task 4 Identify gaps and define mitigation plans Task 5 Finalize and prepare documentation (including specific peer review) Task 6 Future directions and research plans Task 7 End-of-Project Webinar Sep Oct Nov Dec Jan March April Note: Task 5 will proceed while waiting for additional data from testing. The project team will decide if the recommendations should be released based on available data. The SOW will be revised or a new SOW will be written if it is determined that additional testing is necessary. (This may not apply if we make schedule changes.) NOTE: All changes to SOW must be approved by the TC (version control) Page 4 of 5 Strain Guidance for PCBAs, Version #1.7, March 7,

5 Methodology and Resources Resources: Team members from participating companies Project Monitoring Plans This project falls under the general category denoted as a Standards Development, i.e., given a set of materials and/or processes, these projects define a usable range for each set. The projects would also identify an appropriate standards body to which a proposal could be submitted to make the sets part of the published standards. The purpose of specification projects may also be to prepare white papers for industry distribution with the ultimate goal of making new specifications into de facto standards. Project monitoring plans are as follows: Ensure open lines of communication among participants Frequent conference calls as needed Meeting minutes provided through Follow-up with individuals on an as-needed basis Workshops and face-to-face meetings as appropriate Mid-project technical review and progress reports at regularly scheduled inemi meetings Track and document approimate Man-Months per quarter per team member (this will require the active members of the team to provide estimates) Track and document approimate number of people on the project per quarter (this can be tracked through inemi's WebE account) Project results, including conference presentations, technical papers, end-of-project webinar, etc., will be published on the inemi website. Outcome of the Project Technical paper/whitepaper that will be delivered to IPC/JEDEC for publication Subject matter presentations at major electronics industry conferences General and Administrative Guidelines General and Administrative Guidelines for this project and all other inemi Projects are documented at NOTE: All changes to SOW must be approved by the TC (version control) Page 5 of 5 Strain Guidance for PCBAs, Version #1.7, March 7,