Precision Bending Tester for Flexible Electronics

Challenges

• A need for a repeatable, verifiable bending test for sensitive flexible electronics, including reliable electrical contact during dynamic motion to validate performance under mechanical stress.
• Specific requirements:
  
  • Adjustable bend radius 0.5–5.0 mm (nominal range)
  • Bend angle range 0–180° with defined target angles (e.g., 0/45/90/180°)
  • Uniform circular arc (no flattening or asymmetry)
  • Electrical contact stability during bending (no interruption)
  • Repeatability of flap motion (position/angle)
  • Host communication and triggers (Start/Stop, Flat/Bent position, dynamic movement)
  • Safety: E-stop and interlocks, 230 VAC supply validation, ESD/grounding concept
  • Quick set-up/clamping time for dummy/DUT

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Objectives:

• Deliver a validated bending test system that supports multiple bend radii and programmable angle profiles/cycles to standardise test campaigns and generate comparable results across designs.

Konrad Technologies implemented a compact, enclosed bending test machine with transparent guarding and integrated controls, designed to clamp, contact, and bend flexible parts in defined cycles with repeatable geometry settings.

Functions:

• Secure clamping across DUT size range
• Bend radius set-up and verification (mechanical stops + arc measurement)
• Angle control 0–180° and repeatable cycling (e.g., 0–90° process or customer profiles)
• Electrical contacting during motion (continuity / signal stability monitoring)
• Host communication, triggers and status signals (Start/Stop, Flat/Bent, etc.)
• Safety features (E-stop, interlocks) and ESD/ground path verification

Technologies/processes:

• Mechanical radius/angle architecture with defined stops
• Repeatable flap mechanism
• Safety enclosure/interlocks
• PC/controller interface for commands, triggers and test execution

Applied test procedures:

‍FAT verification against a structured requirement list:

• Radius and angle measurement
• Repeatability over multiple cycles
• Visual arc-shape inspection
• Continuity test during motion
• Communication/trigger validation
• Safety/interlock testing
• ESD/ground resistance check
• 230 VAC supply verification
• Operation checks within specified temperature/humidity window

Challenges during implementation and solution:

‍At very small radii (e.g., 0.5 mm RoC) the sample can show an undesired inward kink/reverse bend tendency depending on loading conditions. This was mitigated by introducing a pre-centring/pre-angling step during loading that gently guides the sample into the intended bend direction (without over-pressing). After loading, the system returns to the standard sequence: flaps close to a coplanar/parallel position, contacting is closed, and then the normal bending cycles run.

From this solution the customer gained a validated, repeatable bending test platform enabling standardised evaluation of flexible electronic parts with configurable radii/angles and stable electrical contacting — supporting faster development iterations and consistent data.

Measurable improvement:

• Repeatable and verifiable test conditions (radius/angle/cycle definition)
• Reduced test variability through defined loading/clamping strategy
• Structured FAT acceptance as a foundation for internal approvals and future test campaigns

‍Strengths that contributed most to the success of this project:

• Rapid, customer-specific mechanical/mechatronic development
• Structured FAT execution with measurable acceptance criteria
• Close, iterative collaboration (PoC-oriented engineering)
• Focus on usability, safety, and test repeatability

Key insights and best practices gained from this project:

• For smallest radii, controlled guidance during the loading phase is crucial to avoid reverse kinks.
• Contacting needs tolerance-robust design for dynamic motion (stack-up, spring travel, strain relief).
• Early alignment on measurable acceptance criteria accelerates FAT and reduces ambiguity.