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Starrflex-Technik

Besonderheiten und Anwendungen

40 Jahre Eltroplan 4.07.2019

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Hans-Joerg Etter

CEO

Optiprint AG

Berneck, Switzerland

+41 71 747 86 85

hj.etter@optiprint.ch

www.optiprint.ch

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Agenda

• Introduction

• Advantages and disadvantages of Flex-Rigid-PCBs

• Material selection

• Surface Finishes

• Cost drivers

• PCB-samples

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Optiprint

Optiprint Berneck

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Products and Prospectives

HF pcbs

Flexible and Rigid-flexible pcbs

Very fine lines pcbs

Special products

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Trade – Mix 2018

50%

36%

9%

Trade

Mix

Medical

Telecommunication

Security/Defence

Space/Aviation

Industry

EMS

Automotive

Others

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Product – Mix 2018

47%

50%

3%

Products RF

Flex

FR4

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Revenue/Sales - Employees

100

105

110

115

120

125

130

2012 2013 2014 2015 2016 2017 2018

Employees

15

17

19

21

23

25

2012 2013 2014 2015 2016 2017 2018

€

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Goals

• Know the possibilities and risks of Flex-Rigid-PCBs

• Know some important design rules

• Know common materials

• Know common surface finishes

• Understand cost drivers

• See samples of Flex-Rigid-PCB

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Remarks

• The following informations are basic guidelines for the construction of flex-rigid-PCB

• Special Design requires special processes. Ask your PCB-Producer if you have designs which do not follow the guide lines

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Agenda

• Introduction

• Advantages and disadvantages of Flex-Rigid-PCBs

• Material selection

• Surface Finishes

• Cost drivers

• PCB-samples

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Advantages

• Reduced assembly effort

• Space saving, Miniaturization

• Reduced weight

• Increased reliability

• increased connection quality

Reduced cost and space

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Disadvantages

• Special construction guide lines

• New PCB technology with increased design requirements

• Pick&place and assembly are more challenging

• More complex PCB production (higher cost for PCB)

• Different materials in rigid and flex area -> Impedance

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Design Rules

• Avoid PTH in bending area

• Distance drill holes from flex-rigid transition >1.0mm

• Distance pattern from flex-rigid transition >0.3mm

• Increase stability with copper

• Solid copper or chess pattern

• Teardrops

• IPC-2223

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Delivery Panel

• stability

• X-outs allowed

• large milling radius

• spacing between PCB

• Optimised for PCB-Manufacturer Production Panel

– E.g. Optiprint: 560x410 mm and 410x255 mm

• Fiducials and holes acc. to assembly

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Neutral bending zones

Wrong

Right

Flex section Rigid Rigid

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Minimal Bending radius

• 𝑅 = 𝑑2 + 𝑐 ∗ 100−𝐸𝐵𝐸𝐵 − 𝐷 [IPC-2223] – 𝑅 = bending radius – 𝑑 = thickness dielectricum with adhesive – 𝑐 = copper thickness – 𝐸𝐵 = % copper tension

• Rolled copper <16%

• ED-Copper < 11%

• Assembly ≈ 10%

• Dynamic bending ≈ 0.3% – 𝐷 = thickness coverlay with adhesive

Bending Radius = Thickness x 10

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Agenda

• Introduction

• Advantages and disadvantages of Flex-Rigid-PCBs

• Material selection

• Surface Finishes

• Cost drivers

• PCB-samples

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Flex materials

• Polyimide with adhesive

• Polyimide without adhesive

• Polyimid with sputtered copper

• LCP (Liquid Crystal Polymer)

• Material thicknesses: 12.5…125µm

• Copper thickness: 5…70µm

• Producers: DuPont, Espanex, Sheldahl, Thinflex, Krempel, Rogers

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Flexible materials with adhesive

• Epoxy- or acrylic-based adhesive between polyimide and copper

• Thickness in data sheet describes polyimide thickness

• Applications: mostly single- and double sided PCB

• Advantages: good pricing, very good peel strength

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Flexible materials without adhesive

• Without adhesive

• Sputtered copper as bonding agent

• For very thin copper thickness (<18µm) only available as ED-Cu

• Applications: Multilayer, Flex-Rigid

• Advantages: dimensional stability, defined electrical properties, high temperature resistance

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ED-Copperfoil

• ED = electro deposited = galvanic copper

• Often used for flex materials

• Not suited for extremely dynamic bending

• Different ED-Copper types available

– ED-HD (high ductility)

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RA-Copperfoil

• RA = rolled annealed = rolled copper

• Suited for dynamic bending

• Copper grain direction must be considered

• More expensive than ED-copper

• Copper plating (PTH) voids advantages

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Material selection

Best choice

1. Adhesiveless Material

2. Material with acryl-based adhesive

3. Material with epoxy-based adhesive

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Agenda

• Introduction

• Advantages and disadvantages of Flex-Rigid-PCBs

• Material selection

• Surface Finishes

• Cost drivers

• PCB-samples

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Cover surface

• Photosensitive, flexible solder mask

– Air spray

– Screen printing

• Coverlay (Polyimide)

– Mechanicaly structured

– Bonded with heat, pressure and vacuum

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Flexible soldermask

• Low-cost solution

• For low bending requirements (No buckling)

• No dynamic bending

• Bending radius >5mm

• Typical thickness 20µm

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Coverlay

• For high bending requirements

• Dynamic bending with optimised design and copper- and material-selection

• Good isolation (electrical and mechanical)

• Fine structures require laser cutting

• Flex-Rigid with mutliple flexible-cores separate cores

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Surface finish

• Chem. Nickel/Gold (ENIG)

– Only in rigid area

– Versatile standard finish

• Chem. Nickel/Palladium/Gold (ENEPIG)

– Only in rigid area

– Suited for Gold wire bonding

• Chem. Ag/Au (ISIG)

– New bendable finish

– Suited for Gold wire bonding

• ENTEK (OSP)

– Low-cost

– 1-2 times solderable

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Surface finish Properties HAL OSP ENIG ENEPIG ENIGEG EPIG ASIG ISIG Chem

Ag Chem

Sn

in-house external in-house in-house in-house external in-house external external external

Wire Bonding no no yes yes yes yes yes yes no no

Multiple

Solderability

yes limited yes yes yes yes yes yes yes yes

Pressfit

Technology

limited limited limited yes limited yes yes yes yes yes

Planarity no yes yes yes yes yes yes yes yes yes

Fine Pitch

Application

limited yes yes yes yes yes yes yes yes yes

Process

Maintenance

high low low low low low low low low low

Process Effort medium low medium medium high medium medium medium medium high

Process Cost medium low high high high high medium medium medium medium

Operating Safety bad good good good good good good good good good

Thermal Stress high low low low low low low low low low

Typical

Thickness

3-25µm 0.2-

0.5µm

Ni 3-

7µm

Au 0.05-

0.1µm

Ni 3-

7µm/ Pd

0.05-

0.3µm/ Au

0.015-

0.05µm

Ni 3-

7µm/ Au

0.4-

1.1µm

Pd 0.1-

0.2

Au 0.1-

0.2

Ag 0.12-

0.25µm

Au 0.02-

0.06µm

Ag 0.1-

0.4µm

Au 0.05-

0.2µm

Ag 0.15-

0.45µm

0.8-1µm

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Agenda

• Introduction

• Advantages and disadvantages of Flex-Rigid-PCBs

• Material selection

• Surface Finishes

• Cost drivers

• PCB-samples

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Cost split of a PCB

Flex material

Rigid Material

Bonding

Drilling

Plating

Other

To be discussed with your PCB supplier!

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Cost drivers

• Reduce drill holes

• Reduce bonding stages

• Reduce number of layers

• Reduce number of plating stages

• Use symmetric buildup

• Increase line/space

• Allow X-outs

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Agenda

• Introduction

• Advantages and disadvantages of Flex-Rigid-PCB

• Material selection

• Surface Finishes

• Cost drivers

• PCB-samples

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4-layer rigid-flex board

Medical Application

Sensorhand

Knee/leg prothesis

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4-layer rigid-flex board

Medical Application (in ear hearing aid)

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12-layer rigid flex board

Automotive Application (Formula 1)

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8-layer rigid flex board

Automotive Application (Engine Management)

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Aerospace Application

12-layer rigid-flex board

415mm x 393mm

16.33” x 15.47”

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16-layer rigid-flex

Safety Electronics Application

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2-layer rigid-flex board

Industrial Application

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10-layer rigid-flex board

Industrial Application – flatest e-motor

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Flexible multilayer

• 3-layer Flexible mulitlayer

• 0,3 mm total thickness

• 125 µm „flying leads“ galvanic tinned

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Laser cut profiles

• Edge spacing tolerances ± 10 μm to max ± 25 μm

• 80 μm microvias (through and blindholes)

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Rigid-flexible multilayer

• 8-layer multilayer

• flexible inner layer with coverlay

• 100 µm conductor widths and spacing on both sides 0,2 mm blind vias

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Rigid-flexible multilayer

• 6 flexible layers with coverlay

• 4 rigid layers on FR4

• Tight bend-radii possible

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Heatsink rigid-flexible multilayer

• Optimal heat dissipation through 1 mm copper plate

• 2 layers on Polyimid foil

• 2 layers on FR4 material

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Thermal Vias

• Paste, Copper, Cap plating • Short heat ways • Short bonding wires

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Ticer Technology

• Resistors directly formed during the PCB process

• 3-layer Rogers 4350 Multilayer • Thickness 1.15 mm • 25, 50, 100 Ohms/Square

100 Ohm Ticer foil

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Questions?

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Many thanks for your attention

Hans-Joerg Etter

Email: hj.etter@optiprint.ch

Telefon: +41 71 747 86 85

Web: www.optiprint.ch