IPC Standards Committee Reports — Base Materials, Fabrication Processes, Boards, Embedded Devices

The second posting in a series of updates from IPC standards committee meetings held at IPC Midwest.

Base Materials

The 3-11 Laminate/Prepreg Materials Subcommittee revised IPC-4101, Specification for Base Materials for Rigid and Multilayer Printed Boards to its D revision. Changes include: a) DMA thermal analysis testing for more accurate Tg measurement for approximately 20 percent of the current 66 specification sheets; b) insertion of property of fracture toughness of laminate resin as an optional test and c) clarification of the use of N/A in all of the specification sheets.  The subcommittee postponed grouping similar specification sheets into families until the following revision.  The subcommittee will propose another concept on “FR-4” laminate and prepreg to the balloting Standards Technical Panel (STP) for the UL 746E standard in order to maintain some continued utilization of MCIL within epoxy-based families.

The 3-11f UL/CSA Task Group addressed the proposed FR-4 re-classification issue that failed at the UL ballot level.  The 3-11 IPC Subcommittee is fleshing out a new proposal for a UL STP and the draft was presented and reviewed at this task group meeting.

The 3-11g Corrosion of Metal Finishes Task Group presented the status of round robin testing in five separate mixed flowing gas chambers, but no conclusive results were available for discussion. While four of five facilities have completed their data generation, compilation and analysis of the raw data is still in the works. The group also discussed conducting a much simpler test, “flowers of sulfur.”

The 3-12a Metallic Foil Task Group reviewed round robin testing on non-contact surface roughness measuring equipment to measure four roughness standards at 12 separate facilities. A test method draft of TM-650, Method 2.2.22 on non-contact roughness measurements was also reviewed at and will be finalized once the round robin measurements of the standard are completed. Some gauge R&R measurements were shown at the meeting with more to be analyzed as the raw measurement data is submitted from the members of the test group.

The 3-12d Woven Glass Reinforcement Task Group progressed IPC-4412, Specification for Finished Fabric Woven from ‘‘E’’ Glass for Printed Boards to its B revision.  The document should be balloted and approved for release by IPC APEX EXPO® 2013.

Fabrication Processes

The 4-14 Plating Processes Subcommittee resolved several technical comments submitted on the final draft of IPC-4556, Specification for Electroless Nickel/Electroless Palladium/Immersion Gold Plating for Printed Circuit Boards.  The subcommittee also discussed efforts planned for the A revision of the IPC-4552 specification that addresses ENIG surface finish.

Flexible Circuits

The D-11 Flexible Circuits Design Subcommittee reviewed new content for a future D revision of IPC-2223, Sectional Design Standard for Flexible Printed Boards. This included best practices for the design of circuits with controlled impedance, estimation of minimum bend radius for flex and rigid-flex printed boards, and guidance on HDI/microvia design.

The D-12 Flexible Circuits Performance Subcommittee continued work on revision C of IPC-6013, Qualification and Performance Specification for Flexible Printed Boards. The subcommittee focused on minimum external conductor thickness requirements after plating for various flexible printed board types.  A Final Draft will be submitted for industry review and comment in late 2012.

The D-13 Flexible Circuits Base Materials Subcommittee successfully pushed IPC-4203A Adhesive Coated Dielectric Films for Use as Cover Sheets for Flexible Printed Circuitry and Flexible Adhesive Bonding Films to the Final Draft stage and sent out the document for industry comment.

The D-15 Flexible Circuits Test Methods Subcommittee completed the Final Draft of the B revision of TM 2.4.17.1 on propogation tear strength of flexible film materials. The document was sent to the 7-11 Test Methods Subcommittee for their comments prior to entering the updated test method into IPC-TM-650.

Rigid Printed Boards

The D-31b IPC-2221/2222 Task Group announced the successful ballot of revision B of IPC-2221, Generic Standard on Printed Board Design.  The new revision, the first for this standard in nearly ten years, is expected to be published in November 2012.

The D-33a Rigid Printed Board Performance Specifications and 7-31a IPC-A-600 Task Groups continued efforts for a future revision D of IPC-6012, Qualification and Performance Specification for Rigid Printed Boards. The task group viewed presentations from subgroups actively working via a series of web conferences on the following subjects: metal-based printed board acceptance criteria, updates to HDI/microvia criteria, and an Amendment 1 to IPC-6012C that addresses lot frequency testing and periodic conformance testing with the new 1-10c test coupon set that will be released with IPC-2221B later in 2012.  Doug Pauls, Rockwell Collins, also presented to the group on how IPC-6012 could be revised to call upon ion chromatography (IC) testing in place of resistivity of solvent extract (ROSE) testing for determining the amount of ionic residues on printed boards.

The D-35 Board Storage and Handling Subcommittee discussed goals for revising IPC-1601, Printed Board Handling and Storage Guidelines. This included relevant thermal stress testing (solder float vs. convection reflow), capacitance testing for moisture content, humidity control for board storage, testing for solderability after baking, and how the standard might be transformed from a guideline to a specification.

Embedded Devices

The D-55 Embedded Devices Process Implementation Subcommittee is working on IPC-7092, Design and Assembly Process Implementation for Embedded Components which describes the design and assembly challenges for implementing passive and active components in either formed or inserted methodology in a printed board. Emphasis in this new standard is on the fabrication and assembly processes, and a new board description methodology was discussed.

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