Overview
IEC TR 63018:2015 provides a guideline and measurement method for assessing and improving signal loss in flexible printed circuit boards (FPCBs) when applying noise suppression materials (NSMs). The Technical Report defines test specimen design and a network-analyzer-based procedure to measure the variation in transmission loss introduced by NSMs (i.e., comparing a bare FPCB to a shield FPCB). The report does not prescribe FPCB structures or materials beyond the measurement method - it focuses on quantifying the effect of NSMs on high‑frequency signal loss.
Key topics and technical requirements
- Measurement approach
- Use of a network analyzer to record S-parameters (S11, S21) and quantify transmission loss over a specified frequency range.
- Block diagram and example setup for signal-loss measurement (including coaxial cables and SMA terminals).
- Test specimen design
- Comparative coupons containing both bare and shielded regions on the same board to enable uniform, side‑by‑side measurement.
- Specimen length recommended to be over 5 cm for stable results.
- Use of SMA connectors on specimen ends; Cu trace widths selected within manufacturing tolerances.
- Via holes are important to ensure electrical contact between NSM/shield conductive adhesive and ground; size/spacing to be agreed between user and supplier (AABUS).
- Shield region cross-section (example values from the report)
- Shield insulation layer: 5 µm
- Shield conductive layer: 0.1 / 2 µm (as shown in the illustrative cross‑section)
- Shield conductive adhesive layer: 10 µm
- Copper conductor examples: ~23 µm, PI and adhesive layer thicknesses listed in the figure.
- Test procedure elements
- Preparation steps: lamination of NSM to half the board, marking trace widths, connector attachment.
- Measurement setup: network analyzer configuration (frequency range, dielectric constant), connection via SMA/coax, data capture, calculation and analysis of signal loss variation (bare vs shielded).
- Analysis and improvement
- Methods to assess how NSMs increase signal loss and recommendations for design or material selection to minimize signal degradation while achieving EMI suppression.
Applications and users
IEC TR 63018 is practical for:
- FPCB manufacturers and designers optimizing high‑frequency signal integrity while applying NSMs.
- NSM suppliers validating absorber performance and impact on transmission loss.
- Test laboratories and QA teams performing comparative measurements on shielded vs bare FPCBs.
- Electronics OEMs (smartphones, tablets, display and mobile devices) specifying acceptance criteria for FPCB EMI mitigation.
Keywords naturally included: flexible printed circuit boards, FPCBs, noise suppression materials (NSMs), signal loss, EMI suppression, network analyzer, SMA, shield FPCB, transmission loss.
Related standards
- IEC 62333-1:2006 - Noise suppression sheet for digital devices and equipment (referenced normative document in IEC TR 63018).