sonochemical surface modification of electronic materials ... · sonochemistry centre at coventry...

Sonochemical Surface Modification of Electronic Materials

Dr Andy Cobley

The Sonochemistry Centreat Coventry University

New Developments in PCB and Interconnect Manufacturing NAMTEC, Rotherham UK

4th August 2009

Sonochemistry Centre at Coventry University “The Home of Sound Science”

Agenda

1.Surface Modification in Electronic ManufacturingProblems associated with traditional methods

2.What is SonochemistryAcoustic cavitation

Advantages for surface modification

3.Sonochemical Surface Modification

Preliminary work

Optimisation

Commercial applications

4. Lean, Green and Clean Processing?


Traditional ‘Wet Chemical’ Surface ModificationSubstrates Chemistry HazardsPCBs, MIDs other polymers

Solvent Swell VOC, flammable

PCBs, MIDs other polymers

Alkaline Permanganate

Highly caustic, strong oxidant

ABS Chromic acid Carcinogenic, highly acidic

Ceramics, glass

Hydrofluoric acid

Causes burns, targets bone

•Hazardous Chemistry

•VOC’s, carcinogens, corrosive

•Environmental and health and safety legislation

•High Waste Treatment costs


Traditional ‘Wet’ Surface ModificationSummary

Traditional surface modification processes characterised by…..

•Long process times

•High temperature baths

•High water usage

•Hazardous chemistry

CAN SONOCHEMISTRY HELP ?


SonochemistryThe effect of sound on the chemistry of a solution

I I I I I I I I 0 10 10 10 10 10 10 10

2 3 4 5 6 7

Human hearing 16Hz - 18kHz

Conventional power ultrasound 20kHz - 100kHz

Extended range for sonochemistry 20kHz - 2MHz

Diagnostic ultrasound 5MHz - 10MHz

THE FREQUENCY RANGES OF SOUND

I I I I I I I I 0 10 10 10 10 10 10 10

2 3 4 5 6 7

Human hearing 16Hz - 18kHz

Conventional power ultrasound 20kHz - 100kHz

Extended range for sonochemistry 20kHz - 2MHz

Diagnostic ultrasound 5MHz - 10MHz

THE FREQUENCY RANGES OF SOUND


Sonochemical Surface ModificationAcoustic Cavitation

5000 oC2000 ats

bubbleforms

bubble grows in successive cycles

reachesunstable size

undergoesviolent collapse

compression compression

rarefactionrarefaction rarefaction rarefaction rarefaction


5000 oC2000 ats5000 oC2000 ats

bubbleforms

bubble grows in successive cycles

reachesunstable size

undergoesviolent collapse



compression compressioncompression compression




boundary layersolid surface

Acoustic Cavitation in a liquid NEAR A SURFACE

UNSYMMETRIC COLLAPSEInrush of liquid from one sideof the collapsing bubbleproduces powerful jet of liquid targeted at surface

•Thinning of diffusion layer•Surface Cleaning•Surface activation•Improved mass and heat transfer

Video courtesy of University of Twente, Netherlands.and Shimadzu Europa GmbH, Duisburg, Germany

Microjetting/Microstreaming


Microjetting/Microstreaming

DEMO


Sonochemical Surface Modification

• Microjetting– Mechanical/physical attack of surface– Scrubbing/cleaning action– Destruction of boundary layers– Movement of reactants to, and

products/debris away from, the surface• Extreme temperatures and pressures

– Chemical/oxidative attack of the surface due to oxidative species

– Breaking of bonds on surface of material– Chemical reactions on surface


Sonochemical Surface Modification Original Research Concept

Use ultrasound to make existing surface modification processes more ‘sustainable’

•Reduce chemical concentrations

•Reduce process times

•Reduce temperatures


Sonochemical Surface Modification

Isola 370HR – Tg 180 ºC

Materials Tested

Cycolac S705 – ABS/PC

Noryl HM4025 – Polyphenylene ester / polystyreneCourtesy of Moulded Circuits

Ceramic Material


Experimental Set-upPreliminary work

20 kHz Ultrasonic probe

Water in

Water out

Water Jacket

Solution

Sample holder

Sample

Thermostat

•All experiments performed at 40 ºC


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

0.00

0.05

0.10

0.15

0.20

Wei

ght L

oss

(mg/

cm2 )

Solution Code

Without UltrasonicsWith ultrasonics

Sonochemical Surface ModificationEffect of Ultrasound on Existing Surface Modification Processes

Weight loss results for Ceramic Material

DI Water


Sonochemical Surface Modification of Ceramic

30 minutes HF Etch

1 minute HF Etch 1 minute Sonication in Water, 20 kHz

30 minutes Sonication in Water, 20 kHz


Ductile-like area vs. sonication time

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60

Sonication time (minutes)

Perc

enta

ge (%

) of d

uctil

e-lik

e tra

cks

Sonochemical Surface Modification of Ceramic


Sonochemical Surface Modification in Water20 kHz Horn, 29.3 W / cm2, 60 minutes in DI Water, 40 ºC

Isola 370HR as received x500 After Sonication x500

Noryl HM4025 as received x500 After Sonication x500


Sonochemical Surface ModificationConclusions from Preliminary work

Initial work indicated that sonochemical surface modification could be achieved in water – a more sustainable liquid medium


Sonochemical Surface Modification in Water Optimization of Ultrasonic Frequency

Noryl HM4025, 40 ºC, 30 minutes


Sonochemical Surface Modification in WaterOptimization of Ultrasonic Intensity at 20 kHz

Effect of Ultrasonic Intensity on Weight loss for Noryl HM402520 kHz, DI Water, 40 ºC, 15 minutes


Sonochemical Surface Modification in WaterOptimization of Probe to Sample Distance

Effect of Probe to Sample Distance on Weight Loss for Isola 370HR20 kHz, 4.8 Wcm-2, DI Water, 40 ºC

-0.0500

0.0000

0.0500

0.1000

0.1500

0.2000

0.2500

0.3000

0 10 20 30 40 50 60

Wei

ght L

oss (

mg/

cm2 )

Time (minutes)

5 mm probe to sample distance25 mm probe to sample distance


Sonochemical Surface Modification in Water Other Factors Affecting Process

Standard Process

Bubbled Argon1% 3323

Low temperature

‘Standard’ Process20 KHz Ultrasonic probeDI water @ 40 ºCIntensity – 4.8 W/cm2Time – 15 minutes

Isola 370HR


Sonochemical Surface Modification in WaterEffect of Optimization on Weight Loss for Noryl HM4025

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Wei

ght L

oss m

g/cm

229.3 W/cm2, 40 ºC, 60 minutes

4.8 W/cm2, 6 ºC, 15 minutes


Sonochemical Surface Modification of ABSModified process

As received After Sonication at 40 kHz


Potential Commercial Applications

Metallization of Polymeric Microspheres


Sonochemical Surface Modification of Polystyrene Polymeric Microspheres

As received After Sonication at 20 kHz


Electroless Copper Plated Polystyrene Microspheres

UntreatedSonicated at 20 kHz


Sonochemical Surface Modification of Electronic MaterialsConclusions

• Significant sonochemical surface modification can be achieved on a variety of materials used in electronic manufacture using water as the liquid medium

• The project has identified a number of factors influencing sonochemical surface modification

– Frequency– Ultrasonic intensity– Probe to sample spacing– Liquid temperature– Added surfactant etc

• Under optimised conditions process times reduced from 60 minutes to 15 minutes and weight loss has increased by a factor of 4 on Noryl material

• Other factors have also been identified which can further enhance the sonochemical surface modification and patent protection is being sought

• The project has produced a technology platform from which potential commercial applications are emerging


Sonochemical Surface ModificationA route to Lean, Green and Clean

Manufacturing ?

LEANOne stage process

GREENLower temperatures, reduced energy costs, less rinsing, lower

waste treatment costs.

CLEANNon-hazardous chemistry


The Sonochemistry Centre at Coventry UniversityFaculty of Health and Life Sciences

Coventry UniversityCoventry, CV1 5FB, UK

www.coventry.ac.uk/sonochemistry

CONTACT DETAILS

[email protected] - +44 (0) 24 76 888 624

Mobile – 07706 955 901Fax +44 (0) 24 76 888173


Sonochemical Surface ModificationProject funded by

Industrial and Academic Partners

MOULDED CIRCUITS LTD


Thank you

Any Questions ?

sonochemical surface modification of electronic materials ... · sonochemistry centre at coventry...

Documents