Molded Interconnect Device Molded Interconnect Device (MID) - - PowerPoint PPT Presentation

MID Manufacturing: Advances in

Metallization Plating Technologies Metallization Plating Technologies Leading to Improved Yields

9th International Congress Molded Interconnect Devices MID 2010 September 30, 2010 Richard C. Retallick Senior R&D Manager, Central Research rretallick@macdermid.com

Molded Interconnect Device

• Molded Interconnect

Device (MID) Device (MID)

– A 3 dimensional structure used predominately as antennas for mobile communications

• Selective Plating

– The MID consists of plateable and non- plateable areas which predominately fall into 4 y types

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Molded Interconnect Device

• Main categories of selectively plated MIDs in production

– Double-shot no palladium (DSNP) – Double-shot with palladium (DSP) – Laser Direct Structuring (LDS)

DSNP DSP LDS

2-shot mold 2-shot mold 1-shot mold Cr Etch Cr Etch Laser Structure Palladium catalyst Electroless Copper Electroless Copper Palladium catalyst Electroless Copper Electroless Copper Reducer Final Finish Final Finish Electroless Copper Electroless Copper Final Finish

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Manufactured MIDs

• Double shot no Palladium (DSNP)

– A 2-shot injection mold process A l t bl l i ld d i th fi t h t d i th l ti l – A plateable polymer is molded in the first shot and is then selectively

• vermolded with a second non-plateable material, leaving some

areas of the first material exposed. – An etching step is used to roughen the plateable polymer g p g p p y – A palladium catalyst solution is required to activate the plateable polymer to allow copper plating.

• Double shot Palladium (DSP)

– Same as above BUT palladium is impregnated into the plateable

• polymer. Therefore no additional activation process is required.

An etching step is sed to e pose the palladi m in the plateable – An etching step is used to expose the palladium in the plateable polymer so that those areas can be plated with copper.

Both DSNP and DSP manufacturing processes are used Both DSNP and DSP manufacturing processes are used primarily for mass production of a single MID design.

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Manufactured MIDs

• Laser Direct Structuring (LDS)

– A patented process developed, marketed and sold by LPKF A l ti “d d” ith t l t i ld d t f th MID – A plastic “doped” with catalyst is molded to form the MID

• Common plastic is PC/ABS (polycarbonate/acrylonitrile butadiene

styrene)

• Many other plastic choices based on environmental factors

y p

• Common dopant is a mixed metal oxide typically containing copper

– A laser is used to form the pattern or structure on a plateable plastic

• The laser ablates the plastic and exposes and reduces a catalytically

active metal nuclei typically copper active metal nuclei, typically copper.

• The laser also micro roughens the plastic to provide adhesion.
• Eliminate need for chrome etch

– Used for mass production of MIDs p

• Ideally suited for rapid design changes
• Catalytic Ink

– An emerging technology for MID manufacturing – Ink is applied selectively to base plastic using ink jet technologies

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MID Process Sequence

Mold Activate Copper Plate Coppe ate Final Finish

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MID – Copper Metallization

• Full Build Electroless Copper Process

– Two bath system = Strike Bath + Build bath – Two bath system = Strike Bath + Build bath – One bath system

• Deposits copper onto the catalyzed substrate

Deposits copper onto the catalyzed substrate

– typically a minimum thickness of 12 μm is required

• Antenna requirement

– Total plating time is ± 5 hours

• The reaction mechanism is expressed as

Cr, Cu, Pd

[Cu]2+ + 4OH- + 2HCHO Cuo + 2HCOO- + 2H O + H [Cu]2+ + 4OH + 2HCHO Cuo + 2HCOO + 2H2O + H2

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MID – Copper Metallization

• Development and formulation

f h ik d b ild

• f the strike and build

electroless copper baths is critical

• There are a number of

commercially available electroless copper bath being electroless copper bath being used for MID production

• Enhancements to these baths

t id i ld are necessary to avoid yield loss due to skip plating, extraneous plating, and bath instability

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POP and Electronics Plating Expertise

Decorative and Functional and Functional Plating on Plastics Electroless Copper for Electronics A combined expertise in POP and electronics plating applications were crucial in the

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development and optimization of MID plating processes.

MID Plating Challenges

• Skip plating
• Bath Instability / Tank Plateout
• Extraneous plating

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MID – Copper Metallization

• Strike bath

– Optimized to prevent skip plating

• Build bath

– Optimized to prevent extraneous plating plating – Provide uniform copper coverage – High deposition rate required extraneous plating – Proprietary additives used to control rate and focus deposition on strike copper g p q using reaction drivers, NaOH and formaldehyde – Proprietary additives focus deposition reaction to – A controlled deposition rate produces a high quality copper deposit deposition reaction to catalytically active sites on substrate

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Plating of Laser Structured Materials

• Different materials sets

l d ith thi employed with this technology (PC, PCABS, Polyamide LCP etc ) Polyamide, LCP, etc.)

• Plating performance

achieved by optimizing achieved by optimizing chemistry and matching to material choice and lasering parameters.

• Laser structured vehicle,

h t l ft d f shown at left, used for process optimization.

Laser structured test vehicle (4x4 cm) with multiple lasering conditions single piece enables process optimization 12 enables process optimization

Electroless Copper

• Main Reaction drivers

– NaOH HCHO & heat

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– NaOH, HCHO, & heat – Increases copper deposition rate

2 2.5 in

– Controlled and replenished through direct analysis

1.5 2

• ns/30m

analysis

1 micro 0.5 3 6 9 12 [NaOH] g/L

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Electroless Copper

• Reaction stabilizers

– Proprietary chemical

3.5

– Proprietary chemical additives, & air – Decreases copper

2.5 3 in

deposition rate – Controlled by direct analysis and maintenance

1 5 2

• ns/30m

analysis and maintenance additions

1 1.5 micro 0.5 2 4 6 8 10 12 [stabilzer] mL/L

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Electroless Copper

• Side reactions

– Cannizzaro Cannizzaro

• The non-productive reaction and consumption of NaOH with

HCHO to sodium formate and methanol

2 HCHO N OH HCOON CH OH

• By-product build-up

2 HCHO + NaOH HCOONa + CH3OH

y p p

– Measured by increase in specific gravity – Caused by reaction products from copper deposition reaction and Cannizzaro reaction and Cannizzaro reaction.

Cuo + 2HCOONa + 2NaCl + 2H2O + H2

Cr, Cu, Pd

CuCl2 + 4NaOH + 2HCHO

– Leads to bath instability & tank plate-out

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Electroless Copper

• Electroless Copper

– Effects of main analyzable components

• Copper

– Low copper concentration will sacrifice initiation especially

• n LDS substrates

– High concentration can lead to bath instability due to insufficient chelator ratio

• OH

– In Strike bath - Low concentration will cause poor initiation coverage particularly on LDS substrates – In Build bath – Low concentration will slow down plating rate p g effecting output (productivity) – High concentration may lead to over activity, high deposition rates and bath instability

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Electroless Copper

• Electroless Copper

– Effects of main analyzable components

• HCHO (formaldehyde)

– Low concentration will degrade coverage – High concentration may lead to bath instability and increase High concentration may lead to bath instability and increase non-productive side reactions

• Temperature

– Primary contributor to deposition rate Primary contributor to deposition rate – LDS » Strike bath must be run at higher end of operating range to initiate plating to initiate plating – DSNP and DSP » Strike bath should be run at lower end of operating range to prevent bath instability due to Pd from substrate to prevent bath instability due to Pd from substrate

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Electroless Copper

• Electroless Copper

– Effects of Proprietary additives p y

• Bath stabilizer

– Helps control deposition rate and prevent formation and accumulation of insoluble Cu+1 salts accumulation of insoluble Cu+1 salts – Controls deposition rate and bath stability – Periodic replenishment or maintenance adds are based on site-specific operation (bath loading and production volume)

• Reaction site enhancers

– Focuses the deposition reaction to the catalytically active Focuses the deposition reaction to the catalytically active sites on the substrate

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Consistent Process Control

Process Control - Plating Rate

80 90 s 60 70 30 Minutes 40 50 inches - 3 Strike Build 20 30 Cu Micro

copper plating rate analyzed by standardized rate panel method each operating shift assures bath life and high

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1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3

plating yields

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Operating Shifts

Assuring High Yields

A combination of the best chemistry and adherence to “best adherence to best practice” process control assures high production t l t d rates, low costs, and the highest yields. This includes the use

• f simple, effective

chemistry controllers.

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Assuring High Yields

Solution Sparger Air Agitation Control Valve Reserve Formaldehyde Replinishment B Replenishment C Replenishment

Proper equipment selection and engineering also

Pump Filter Bag Air Agitation control Valve A Replenishment To Copper Trap Solution Height Control Heater

engineering also strongly influences plating productivity d i ld

Front Back

and yields. Suppliers must work with fabricators to assure that plating tanks are designed and operated p properly

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Successful Process Demonstration

• Electroless copper process

enhancements are designed to deliver:

– High yields on laser High yields on laser structured, two-shot, and single shot parts from the same chemistry same chemistry – Stable plating chemistry with long and predictable bath life long and predictable bath life – Process simplicity: Easy to use and control Predictable use and control. Predictable plating behavior.

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Successful Process Demonstration

• Demonstrated in piloting and

in large scale production in large scale production (China) to deliver 98%+ plating yields.

• Consistent plating rates and

high yields obtained through simple and reliably simple and reliably controllable chemistry

• Customer training on best
• Customer training on best

practice operation provided to assure ongoing success

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Continuous Process Development

• Electroless Copper

Hi h d b ild – High speed build process

• Target deposition rate of 5μm/hour

– < 3 hours to achieve 12μm < 3 hours to achieve 12μm

– 1 bath system

• Eliminates need for copper strike bath

pp

– Provides more process tanks for higher output

• Reduces number of active components

f – Provides ease of operation and reduced inventory

• Alternative Surface Finishes

– Opportunities to optimize RF and electrical performance

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Thank you for your attention Thank you for your attention

Contributors:

John Swanson Director, Final Finish and Interconnect Technologies jswanson@macdermid.com R b t H ilt Robert Hamilton Technology Manager, MID Technologies rhamilton@macdermid.com Ying (Judy) Ding Ying (Judy) Ding Senior Research Chemist, Central Research jding@macdermid.com

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