IPC Standards Committee Reports — Base Materials, Fabrication, Assembly and Joining, Flexible Circuits

These standards committee reports from IPC APEX EXPO 2015 have been compiled to help keep you up to date on IPC standards committee activities. This is the second in a series of reports.

Base Materials

The 3-11 Laminate/Prepreg Materials Subcommittee successfully examined both Amendments 1 and 2 to the IPC-4101D, Specification for Base Materials for Rigid and Multilayer Printed Boards. Amendment 1 concentrates on handling sections of IPC-4101D that do not cover the use of inorganic fillers in legacy designs, as well as other changes in the D revision. Amendment 1 is moving through its final draft for comments and will shortly move to the ballot stage.

Amendment 2 addresses the needs for reduced contamination levels as desired by the European Space agency, and is in queue to be worked upon behind the efforts with Amendment 1.

The 3-11f UL/CSA Task Group discussed rigid and multilayer materials and printed boards. Specifically, the group addressed the addition of what will be designated as FR-15.0 and FR-15.1 ANSI grade laminates that will not have to be LTTA tested and will meet a 150 OC RTI. These laminates initially started out as more typical FR-4 grades that meet a 130 OC RTI, but were found to meet the 150 OC limit.

The 3-11g Corrosion of Metal Finishes Task Group discussed metal finish corrosion on component leads and printed board surface finishes. The Flowers of Sulfur (FoS) corrosion test method for surface mounted chip resistors will be used for testing some sample coupons once these are assembled with components. History of work on mixed flowing gas testing was reviewed with work occurring to define why the amount of chlorine has such a large variable impact on overall corrosion rate.

The 3-12a Metallic Foil Task Group addressed the non-contact surface roughness test (proposed TM 2.2.22). The task group saw the Gauge R&R evaluation results from the six test sites. While not perfect results, adequate Gauge R&R was realized (<20) to push the test method ahead.

The 3-12d Woven Glass Reinforcement Task Group completed a first round of testing for fabric weave closer to quantify what is currently termed spread glass. The first results need improvement and will be pursued with another round robin of testing on a single woven style. Additionally, another 3 weaves are proposed for addition to the IPC-4412B using the balloting procedure for amendments.

Fabrication Processes

The 4-14 Plating Processes Subcommittee reviewed revision A efforts underway on IPC-4552, Specification for Electroless Nickel/Immersion Gold (ENIG) Plating for Printed Circuit Boards, primarily for those meeting attendees who have not participated in regular teleconferences. The group also reviewed work that has occurred on an amendment 1 to IPC-4556, Specification for Electroless Nickel/Electroless Palladium/Immersion Gold (ENEPIG) Plating for Printed Circuit Boards.

Assembly and Joining

The 5-11c Electronic Assembly Adhesives Task Group is resolving comments from the final draft for industry review distribution of IPC-HDBK-4691, Handbook on Adhesive Bonding of Electronic Assembly Operations. The group plans to distribute the handbook for final ballot in summer and publish by fall 2015.

The 1-13 Land Pattern Subcommittee and 5-21a IPC-7070 Task Group met jointly to consider component mounting issues being addressed in two IPC standards: IPC-7070, Component Mounting: Issues and Recommendations and IPC-7351, Generic Requirements for Surface Mount Design and Land Pattern Standard. IPC-7070 will address component placement issues, while IPC-7351 will address board design, land pattern and through-hole pad issues. Since the board actions in IPC-7351 combine the existing standard with a proposed through-hole standard (IPC-7251), the committee decided to circulate a survey to ensure that all previously involved committee members are informed of these potential actions.

The 5-21g Flip Chip Mounting Task Group continued its work on revision A to IPC-7094, Design and Assembly Process Implementation for Flip Chip and Die Size Components. The group is focusing its attention on expanding the document to include more recent technology for flip-chip application, current trends in terminal designs for higher density flip-chips and modifying substrate and interposer terms to reflect current trends.

The 5-21k IPC-SM-817 SMT Adhesive Task Group re-formed and opened IPC-SM-817, General Requirements for Dielectric Surface Mounting Adhesives, for revision A. This task group will be modify the standard accordingly in the coming months.

The 5-22a J-STD-001 Task Group reviewed more than 80 open action items and comments on IPC J-STD-001F, Requirements for Soldered Electrical and Electronic Assemblies. This task group met a second day to resolve comments on criteria common to both IPC J-STD-001 and IPC-A-610, Acceptability for Electronic Assemblies. IPC staff is now preparing J-STD-001 revision F for ballot.

The 5-22arr J-STD-001/Conformal Coating Material & Application Industry Assessment Task Group discussed the current status of round robin testing and made a number of revisions to measurement protocols.

There were three J-STD-001 related committee meetings. The 5-22as Space Electronic Assemblies Task Group continued work on the addendum used for electronic assemblies that need to operate in micro-gravity, micro-atmosphere environments with extreme temperature excursions and very high mechanical shock and vibration during launch.

The 5-22f IPC-HDKB-001 Task Group had an initial meeting to develop a roadmap to update the handbook to incorporate Revision F changes. In addition, the 5-22bt J-STD-001 Technical Training Committee met to share ideas for improvements to the training program for Revision F. This committee also reviewed the new IPC Certification Quality Initiative, which provides uniquely scrambled exams and electronic training reporting.

The 5-22h Thermal Profiling Guide Task Group held its first meeting and focused on revision A of IPC-7530, Guidelines for Temperature Profiling for Mass Soldering (Reflow & Wave) Processes. The group discussed missing definitions and modification of what thermal profiles should be covered, including special applications of laser, inductive soldering, hot bar, and hot belt. The group also discussed development guidelines, calibration, process control, and process guidelines.

The 5-23a Printed Circuit Board Solderability Specifications Task Group completed work on IPC J-STD-003C, Solderability Tests for Printed Boards. This group is discussing a replacement for the solder float test which has been proven to be unreliable. An amendment with typographical corrections and some clarifications will be published in later this month.

The 5-24b Solder Paste Task Group began review of all test methods originating with the group.

The 5-24c Solder Alloy Task Group discussed how to properly incorporate two new alloy families into the Appendix tables A-1, A-4 and A-5 in the J-STD-006C by an Amendment Ballot process. The decision is to not use trade names or company names in the standard, but to use site IP information, patent number, when such was awarded, and the alloy composition.

Flexible Circuits

The D-11 Flexible Circuits Design Subcommittee met to advance the Working Draft to IPC-2223D, Sectional Design Standard for Flexible Printed Boards. The group reviewed a proposal for a new section that addresses a new cover material used as a bonding agent in rigid-flex designs, which would allow for the elimination of the window “cut-out” of covers in the rigid area. The group also reviewed a proposal to address electroless “flexible nickel” plating for ENIG applications in flexible printed boards, however the current proposal has not yet been accepted due to concerns expressed by the group over the level of reliability testing that has been performed to date on the material.

The D-12 Flexible Circuits Performance Subcommittee met to advance the Working Draft to IPC-6013D, Qualification and Performance Specification for Flexible Printed Boards. Edits were made to text and the supporting illustration Figure 3-15 for the definition of thermal zones in microsection evaluations. The group also reviewed a cross-sectional illustrated drafted by Michael Collier of Teradyne that addresses voiding or delamination in the transition zone between flexible material and rigid material. There is a lack of a corresponding microsection inspection/test for this type of anomaly, and so the group will reconvene via teleconference in early summer 2015 to draft a Destructive Physical Evaluation (DPA) section for IPC-6013D when there is a suspicion of this type of anomaly.

The D-13 Flexible Circuits Base Materials Subcommittee discussed new a modified requirement for propagation tear strength for a polyimide film that would be a slightly lower value for 50 to 100 micron thick material. This will be covered by an Amendment 2 to IPC-4202A.

The D-15 Flexible Circuits Test Methods Subcommittee worked on the TM (Insulation and Moisture Resistance, Flexible Base Dielectric) to what was believed to be a draft of the C revision of the TM. However, after the meeting at the 2015 IPC APEX EXPO, the group has discovered a major flaw in the method as developed and continues its work on revising this test method.

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