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» PCB & ASSEMBLY6. Select correct bend radiusMinimum bend radius is critical. As a general rule forsingle layer with 18 µm Copper• For static bends: Radius ≥6× the flex thickness(B≥6*A)• For dynamic bends: Radius ≥10× the flexthickness (B≥10*A)Tighter bends increase the risk of cracking,especially with copper conductors.7. Avoid placing components in flexareasUnless absolutely necessary, keep components out ofthe flexible regions. Place components on rigid sectionsto prevent solder joint fatigue and mechanicalfailures. If components must be on flex areas, thenuse stiffeners to support the components.8. Use hatched ground planes inflex zonesSolid copper pours limit flexibility. In flex areas, usecross-hatched ground planes to maintain EMIshielding while preserving bendability. Just ensurecontinuity and signal return paths are not compromised.Solid copper pours limit flexibility, in flex areasUse cross-hatchedSource: CEE PCBSource: CEE PCBZusammenfassungFlexible und starr-flexible Leiterplatten sind entscheidendfür moderne, komplexe Elektronikanwendungen und erfordernspezielle Designregeln, um mechanische Belastungenzu bewältigen und Zuverlässigkeit zu gewährleisten.RésuméLes circuits imprimés flexibles et flexo rigides jouent unrôle décisif dans les applications électroniques moderneset délicates. Ils nécessitent des règles de conception particulièrespour résister aux charges mécaniques et garantirleur fiabilité.РезюмеГибкие и жёстко-гибкие печатные платы являютсяключевыми элементами современных сложныхэлектронных приложений и требуют особых правилпроектирования для обеспечения устойчивости кмеханическим нагрузкам и надёжности.9. Optimize stack-up for balanced flexUse symmetrical stack-ups with adhesiveless basematerials whenever possible. This will improve flexlife and reduce unwanted curls. Ensure copperweights and coverlay materials are properly selectedto match your bend performance requirements.10. Collaborate with your manufacturerin an early design stage.Flex and rigid-flex PCBs typically have tighter manufacturingtolerances than traditional rigid PCBs. EarlyDesign for Manufacturability (DFM) reviews with CEEPCB will prevent common design issues and speed upprototyping stages. We will help to optimize yield,cost, and performance.Final ThoughtsFlex and rigid-flex PCBs open new possibilities — butonly when designed with care. Following these ruleshelps ensure your design works not just electrically,but also mechanically.Need help with your flex or rigid-flex design? Contactthe experts at CEE PCB for design reviews,stack-up planning, and high-reliability manufacturingsupport. Get a quote or talk to one of our engineers.www.ceepcb.com30 EPP Europe » 05 | 2025
Product Updates « PCB & ASSEMBLYIntroduction of ROL0 and halogen-free flux-cored wireNo-clean formula maximize the solderabilityIndium Corporation announced the globalavailability of CW-807RS, a high-reliability,halide- and halogen-free flux-coredwire that improves wetting speeds andcycle times for electronics assembly androbot soldering applications. It is a nocleanformula designed to maximize thesolderability of a halogen-free cored wiresolder flux. It is an upgraded version ofthe company’s CW-807 formula, whichhas been popular with electronics assemblersand other customers for manyyears. This new halogen-free version willprovide improved wetting speeds andcontains the company’s industry-leadingspatter control technology.Halogen-free CW-807RS delivers severalbenefits to users, including:• Faster wetting speeds• Clear residues for electronics assemblersthat use high (>385 °C) tiptemperatures and tend to experiencecharring and tip build-up• Improving cycle times in robotic solderingapplications.“The improved wetting and spatter performancemake CW-807RS an excellentno-clean, high-reliability flux-cored wireoption for many of our customers, especiallyin robotic soldering applications,”said Robert McKerrow, Product Managerfor Flux-Cored Wire, Wave Solder Flux,and Bar Solder at Indium Corporation.CW-807RS, a new high-reliability, halide- and halogen-freeflux-cored wire that improves wetting speeds and cycle timesfor electronics assembly and robot soldering applications“We’re excited to now offer this solution,combining cutting-edge innovation withproven technology to meet the needs ofour customers.”CW-807RS provides exceptional benefits inmanual and robotic soldering applicationsrequiring an “L” IPC classification and halogen-freewire, as well as in manual androbotic soldering applications requiringextra wetting power to achieve higherthroughput while remaining halogen-free.Additionally, the spatter control technologywithin the flux produces an aestheticallypleasing board post-soldering byleaving minimal spatteringand a clear to light-coloredresidue.www.indium.comSource: IndiumHandling dense and heavy assembliesHeavy board options added toreflow soldering systemProvider of reflow soldering technology, Vitronics Soltechas launched new Heavy Board options for its Centurion1240 reflow soldering system. This enhancement is designedto provide unmatched thermal performance andmaximum throughput, addressing the evolving challengesof dense and heavy assemblies in the electronicsmanufacturing industry. “The CT 1240 stands out for itsability to meet the most stringent industry requirementswithout increasing the machine’s footprint,” saidthe company. “While many suppliers respond to the increasingdensity of assemblies by extending ovenlength, the company has taken a different approach.The new Heavy Board options enhance the CT 1240’scapabilities, allowing for improved handling of heavierboards while boosting throughput.www.itweae.comSource: ITW EAEThe enhancement to the Centurion 1240 reflow systemis designed to address the evolving challenges of dense andheavy assembliesEPP Europe » 05 | 2025 31
