Miniaturizing Flexible Circuits for use in Medical Electronics. Nate Kreutter 3M

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1 Miniaturizing Flexible Circuits for use in Medical Electronics Nate Kreutter 3M

2 Drivers for Medical Miniaturization

3 Market Drivers for Increased use of Medical Electronics Aging Population Early Detection Prevention More Accurate Diagnosis New Medical Procedures Real Time Analysis New Treatments Improved Quality of Life

4 Disease Prevention Real Time Analysis Improved Analytical Tools Improved Quality of life Early Detection Improved D Health care Point of Care Aging Population Rapid Recovery Accurate Diagnosis MEDICAL MARKET DRIVERS Cost Effective Solutions

5 Medical Electronic Miniaturization Drivers Increased Functionality Increased Wiring Density Limited Space Wiring Complexity

6 Typical Electronic Medical Miniaturization Applications

7 Typical Applications of Electronic Miniaturization in Medical Devices Requiring Flexible circuits Intracardiac echocardiography (Invasive imaging Intravenously of the heart) Internal imaging (camera pill - digestive system) Transesophageal echocardiogram (imaging heart through the esophagus) 3D and 4D ultrasonic Medical Imaging Digital hearing Aids Cochlear implants Defibrillators and pacemakers

8 Enablers for Miniaturization

9 Material Enablers Polymers where the CTE is matched to copper High temperature coatings and materials Ultra thin materials (less than 25um) Adhesive-less metalized substrates Chemical millable materials (chemical etching of dielectric) Photo defined insulators High elongation copper

10 Material & Construction Enablers

11 Circuit Fabrication Enablers Laser direct imaging ( improved resolution, accurate, feature to feature precise positioning, auto compensations, layer to layer alignment Lasers for via generation, patterning dielectric and adding value add features Chemical milling Plating custom plating to only thickness required Sputtering Unique Tie layers and conductive layers Precision punching Etching control Photo resists Roll to Roll processing

12 Circuit Fabrication Enablers

13 Final electronics Assembly Enablers

14 Standard Flex Design compared to One Design for Miniaturization

15 Typical Standard Flex Description Dimension 1 Adhesive 25 um 2 Base Polymer 50um 3 Adhesive 25um 4 Copper um 5 Copper um 6 Nickel 7 Gold 8 Solder mask 25um 9 Space 100um 10 Trace 100um 11 Via diameter 200um

16 Miniaturized flex Description Dimension 1 Adhesive None 2 Base Polymer um 3 Adhesive None 4 Copper um 5 Copper um 6 Nickel 7 Gold 8 Solder mask 15um 9 Space 30um 10 Trace 30um 11 Via diameter 20um

17 Examples of miniaturization features in Flex Fine pitch traces Chemical milled features

18 Via in Pad Flexible circuit Technology Advancement Illustrations Fine pitch with LDI & micro via

19 Miniaturized Flex Cable (Case Study) Application: Medical Ultrasound cable

20 Typical Yield penalty for Flex Miniaturization

21 Miniaturization Standard Surface Area <150 square mm High low High > 25um feature Routing Density Low

22 Relationship Between Yield, Critical Area, and Circuit Pitch Decreasing Circuit Pitch

23 Designing Flex for Miniaturization

24 Design Design elements become much more important, tools exist to ensure robust designs translate into manufacturable products Modeling Electrical Mechanical Thermal Advanced software Efficient Routing algorithms for high density multilayer Design Rule checks Routing Violations continuity

25 Design consideration in Miniaturization Thinner metals and polymers stress from bend, twist and fold mechanical modeling done to understand stress points In Standard flex most designs are over engineered for strength. In miniaturization one can not afford to over engineer with thick wide structures and wide tolerance Design to minimize high stress concentrated areas Minimize high density routing area (see case study)

26 Integration of Materials, Technology and Design Predictive modeling to eliminate number of iterative designs required Using maximum available 3D real-estate by Bending, Folding and twisting Small form factor designs utilizing ridged flex, thus eliminating layers and connectors Combining Chip scale packaging technology with Flex Incorporating embedded Passives and organic actives

27 Testing and Reliability

28 Reliability & Testing Reliability expectations become very application specific There is a need for revised industry standards for miniature constructions There is a gap in testing fine features and structures on mutli-layer interfaces Electrical testing Fine feature testing Off board electrical test structures Tools require high magnification and resolution

29 Miniaturization challenges

30 Challenges with miniaturized flex Increased process control required New materials are required Cleanliness of circuits more important. Ionic Residue s creates issues in electronics where circuitry is essentially (counting electrons) Features closer together are more apt to have residue metals causing isolation resistance issues Smaller vias with less copper in via needs to tested per application end use environments Electrical test fixtures must be planned in advance. Industry standards exist for traditional flex but are not always scalable to miniaturized flexible circuits Available connectors for miniaturization are few. New connectors have not kept up with miniaturization of flex

31 Future of Miniaturized Flex for use in Electronics for Medical Devices

32 Advancement in other areas enabling use of flex for new emerging applications Lapped or thinned IC chips IC integration Chip Scale Packages Printed electronics Flexible battery's OLED displays Wireless energy charging MEMs

33 Future of Miniaturized flex Printed electronics printed passives and active material deposited on flex Increased use of CSP and 3D IC packaging Rigid flex (multilayer rigid area with flex appendages at very small form factors Lapped or thinned chips Flexible batteries Smart flex built with sensors and both active and passive components on board and imbedded

34 Analyzing Communicating Sensing Imaging Multilayer System On Chip CSP Integration

35 THANK YOU!

36 Acronyms AOI Automated Optical Imaging CSP Chip Scale Packages LDI Laser Direct Imaging Flex Flexible circuitry

Flex Circuit Design and Manufacture.

Flex Circuit Design and Manufacture. Hawarden Industrial Park, Manor Lane, Deeside, Flintshire, CH5 3QZ Tel 01244 520510 Fax 01244 520721 [email protected] www.merlincircuit.co.uk Flex Circuit