Flexfilm A Novel Film-based MID Process Dr -Ing Marcus Schuck 1 - - PowerPoint PPT Presentation

Flexfilm – A Novel Film-based MID Process

Dr -Ing Marcus Schuck1 Dr.-Ing. Marcus Schuck

• Prof. Dr.-Ing. Dietmar Drummer2

Dipl.-Ing. Andreas Seefried2 Di l Wi t h I Mi h l F h 2 Dipl.-Wirtsch.-Ing. Michael Fuchs2

1 Jacob Plastics GmbH 2 Institute of Polymer Technology

Jacob Plastics GmbH Bergstraße 31 - 35 91489 Wilhelmsdorf D t hl d / G Institute of Polymer Technology Am Weichselgarten 9 91052 Erlangen D t hl d / G Deutschland / Germany Tel.: +49 (0)9104 / 8270-492 Fax: +49 (0)9104 / 8270-455 m.schuck@jacobplastics.com Deutschland / Germany Tel.: +49 (0)9131 / 85297-00 Fax: +49 (0)9131 / 85297-09 seefried@lkt.uni-erlangen.de

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m.schuck@jacobplastics.com www.jacob-kunststofftechnik.de seefried@lkt.uni erlangen.de www.lkt.uni-erlangen.de

Content Motivation and Goals Performance potential Flexfilm – Performance potential Flexfilm – Application potential Flexfilm Process chain Flexfilm – Film extrusion Hot embossing – Hot embossing – Radiation cross linking – Thermoforming – Injection molding – SMD assembly Outlook

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Summary

Applications of polymer films

Decorative films Flexible circuits Packaging films

[Schlenk]

Market development flexible circuits Market development flexible circuits example: automobile

FFC: flexible flat cables FPC: flexible printed circuits

market volume

estimated market volume EU 2008: FPC: 300 Mio. € FFC 1200 Mi € FPC: flexible printed circuits

3 [Freudenberg]

FFC: 1200 Mio. €

Motivation and Goals State of the art

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Motivation and Goals Performance potential Flexfilm Application of radiation cross linked technical thermoplastics as film thermoplastics as film material for flexible printed circuit boards

3D MID three dimensional formability via thermoforming

+

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3D-MID (multi layer) large-area bonding via injection molding

+

Motivation and Goals Application potential Flexfilm

Rigid/Flex-Interconnections connector SMD

[Lucent]

Appliction of 2D-

[capicard]

Appliction of 2D- Metallization techniques injection molded substrate conductor path Multi layer MID (with through connections)

[Lucent] 6

film

Basics Radiation cross linking

Non Cross Linked Semi Crystalline Polymer Radiation Cross Linked Semi Crystalline Polymer Complete Melting for T > Tm Rubber-elastic Behavior for T > Tm

us

non cross linked cross linked soldering temperature

li k d t ung’s modul radiation cross linked part

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non cross linked part, PA6-GF30, after lead-free soldering (Tmax = 255 °C, 10 min) You

Tg Tm RT

radiation cross linked part, PA6-GF30, after lead-free soldering (Tmax = 255 °C, 10 min)

Process chain Flexfilm Criteria Adhesion of metallization Thermal expansion Thermoformability Thermoformability Adhesion in injection molding Solderability Solderability

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One of the central research targets was to find the optimal time for radiation cross linking within the process chain.

Film extrusion Film thickness

PBT, film extrusion with chill-roll driving speed ess [µm] film thickne pull-off speed [m/min]

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High quality films with thicknesses from 200 µm to 600 µm can be extruded.

Material choice and film extrusion

Radiation cross linkable PBT is commercially available and can be extruded to films. Film extrusion of cross linkable, semi crystalline thermoplastics

Resin PBT V-PTS-Createc-B3HZC Film extrusion Collin ESE E30M Film (radiation cross linkable) Thickness 300 µm Lifocolor COLCOLOR E40/60 1 Weight-% Flat film die 250 °C Chill-roll 80 °C Pull off speed Thickness 300 µm Width 220 mm

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Pull-off speed 1.8 m/min

Hot embossing Process windows for metallization

1 2

experimental stamp layout

0,5 1 2 3

50

peel test p

(according to DIN 53494) pull-off speed: 50 mm/min

copper strip polymer film

F

roll (∅ 5 mm)

Widening of specific hot embossing process window can be reached with di ti li ki d t h d th h i l i t

30 mm test length

radiation cross linking due to enhanced thermo-mechanical resistance. Peel resistances up to 2.5 N/mm may be detected which are mainly influenced by embossing stamp temperature as key process factor.

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Radiation Cross Linking Influence on Mechanical Film Properties

Specimen Type 5A Specimen Type 5A Testing climate Testing climate temperature 23 °C, 50 % rel. humidity Test velocity Test velocity 15 mm/min Tensile Test (according to DIN ISO 527)

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(according to DIN ISO 527)

Metallization and Structuring

Radiation cross linkable PBT-films can be metallized with strip lines cost- effectively by hot embossing, fulfilling the demands of high adhesive force at the same time. Hot embossing onto thermoplastic film substrates same time.

Film (radiation cross linkable) Thickness 300 µm Film (circuit) 18 µm Copper + BlackOxide + Surface finishing (Tin) Hot embossing Press system (Blue Tiger Systems) Radiation Width 220 mm

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Embossing temperature 183°C Embossing pressure 33 N/mm² Embossing time 0,5 sec cross linking Electron energy 5 MeV Dose 5 x 33kGy

Thermoforming Thermoformability of metallization

linear draw ratio Rl angle αi 1.10 65.4° 1.15 60.4° 1 20 56 4°

Thermoforming mold geometry

1.20 56.4° 1.25 53.1° 1.30 50.3° 1.40 45.6°

metallization 18 µm Cu + BlackOxide elongation increase

Elongation at break is ca 2 5 % at 200 °C for the copper foil linear draw ratio in thermoformed parts up to 140

PBT, 600 µm, 5 x 33 kGy painted, without metallization TU = 230 °C αi: 56.44 °, Rl = 1.20 PBT, 600 µm, 5 x 33 kGy painted, with metallization TU = 230 °C αi: 56.44 °, Rl = 1.20 14

Elongation at break is ca. 2.5 % at 200 C for the copper foil, linear draw ratio in thermoformed parts up to 140 % can be reached with hot embossed films. Due to an elongation increase of the polymer film, greater strains than the copper foil’s elongation at break may be reached by thermoforming metallizied films.

Shape Forming and Cutting

Thermoforming of PBT-films prior to the radiation cross linking is not possible, but after the cross linking step film substrates featured with necessary forming properties. Thermoforming of metallized film substrates properties.

Thermoformed insert Thermoforming Film (circuit) Thermoformed insert Various deformation degrees Steepest edge 45,6° Thermoforming Berg Mini M3 Temperature of semi-finished part 240 °C Mold temperature 40 °C Film (circuit) 18 µm Copper + BlackOxide + Surface finish (Tin) Dose 5 x 33kGy

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Mold temperature 40 C Vacuum

Injection molding Film adhesion

Film material PBT V-PTS-Createc B3HZC Injection molding resin PBT V-PTS-Createc B3HZC Injection molding geometry

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Injection molding

Injection molding - mold

Multiple cartridge mold to adjust backmolding geometry to test quality of 1 Adh i b t fil d i d

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• 1. Adhesion between film and resin and
• 2. Soldering resistance

Injection molding

Injection molding film + structure

Thermoformed insert Different draw ratios Steepest edge 45.6° Injection molding Ferromatik Millacron 110t Melt temperature 295°C Injection molded multi-component part Injection molded,

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Steepest edge 45.6 Melt temperature 295 C Mold temperature 80°C Injection molded, thermoformed, cross linked film

SMD assembly Solderability

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Outlook Flexfilm Further possibilities for development steps: – Combined use of copper-clad films and subtractive structuring processes Two sided metallization with through connection – Two-sided metallization with through connection – Thermoforming of entire flexible printed circuits – Realization of Rigid/Flex interconnections

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Summary Flexfilm process With the process chain of Flexfilm three-dimensional interconnect devices can be produced by means of two-dimensional metallization and structuring processes. Thus the Flexfilm process enables the manufacturing of multi layered MIDs. Radiation cross linking may be conducted after film extrusion and has to be carried

• ut at the last after metallization.

E t i f di ti li k bl fil f t h i l i t lli th l ti Extrusion of radiation cross linkable films of technical semi crystalline thermoplastics is feasible. By hot embossing copper films onto the polymer substrate good adhesion can be achieved achieved. Thermoformability is greatly increased by radiation cross linking. Due to an elongation increase of the polymer film, greater strains than the copper foil’s l ti t b k b h d b th f i t lli d fil elongation at break may be reached by thermoforming metallized films. Sufficient adhesion to the film insert is achievable by injection molding. The temperature resistance of radiation cross linked films is sufficient for lead-free f

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reflow soldering.

Acknowledgment Our special thanks go to: Bayerisches Staatsministerium für Wirtschaft, Infrastruktur, Verkehr und Technologie for founding this work within the research project NW0707-0008 Entwicklung strahlenvernetzter Flexfolien in project NW0707-0008 „Entwicklung strahlenvernetzter Flexfolien in Hybridgehäusen“ in the program „Neue Werkstoffe in Bayern“

FAPS

Institute for Manufacturing Automation and Production Systems, Erlangen, Germany, for their support regarding SMD assembly assembly Beta Gamma Service, Saal a.d. Donau, Germany, for the electron beam irradiation of polymer films

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