the sonochemistry centre - loughborough university...sonochemistry centre at coventry university...

An Evaluation of Sonochemical Surface Modification for Electronic Manufacture

Dr Andy Cobley

Prof. Tim Mason

The Sonochemistry Centre

SUMEEPnet Workshop(Sustainable Use of Materials for

Electronic & Electrical Products network)

Henry Ford College, Loughborough University19th March 2008

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

AgendaAgenda1.Surface Modification in Electronic Manufacturing

Problems associated with traditional methods

2.What is SonochemistryAcoustic cavitation

Advantages for surface modification

3.Sonochemical Surface Modification

Screening

Optimisation

Scale-up

4. Evolution of the project

5. Lean, Green and Clean Processing?


Traditional Traditional ‘‘WetWet’’ Surface ModificationSurface Modification

Chemistry Time / min Temp / ºCSolvent Swell 5-15 65-85Rinse 2-6Rinse 2-6Permanganate Etch 5-15 75-85Rinse 2-6Rinse 2-6Neutralizer 3 RT-50Rinse 1-2Rinse 1-2

•Relatively long dwell times

•3 stage process

•High Temperatures required

•High energy costs

•Copious rinsing

•High water costs

Example Example -- DesmearingDesmearing of PCBof PCB’’s or Adhesion Promotion of s or Adhesion Promotion of MIDsMIDs


Traditional Traditional ‘‘WetWet’’ Surface ModificationSurface Modification

Substrates 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 Traditional ‘‘WetWet’’ Surface ModificationSurface Modification SummarySummary

Traditional surface modification processes characterised by…..

•Long process times

•High temperature baths

•High water usage

•Hazardous chemistry

CAN SONOCHEMISTRY HELP ?


SonochemistrySonochemistryThe 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 ModificationSonochemical Surface Modification Acoustic Acoustic CavitationCavitation

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




Sonochemical Surface ModificationSonochemical Surface Modification Generation of Oxidizing Species

Chemicals break down in the cavitation bubble

Sonochemical decomposition of water

H2 O →

Ho + OHo

Ho + O2 →

HO2o

HO2o + HO2

o →

H2 O2 + O2

OHo + OHo →

H2 O2

OHo (Hydroxyl radical) – short lived

HO2o (Perhydroxyl radical) – short lived

H2 O2 (Hydrogen Peroxide)


Sonochemical Surface ModificationSonochemical Surface Modification MicrojettingMicrojetting at a solid surfaceat a solid surface

surface cleaningdestruction of boundary layersurface activationimproved mass and heat transfer

boundary layer

solid surface

Collapse at or near a solid surfaceInrush of liquid from one side of the collapsing bubble

produces powerful jet of liquid targeted at surface



boundary layer

solid surface

Collapse at or near a solid surfaceInrush of liquid from one side of the collapsing bubble

produces powerful jet of liquid targeted at surface


Sonochemical Surface ModificationSonochemical Surface Modification MicrojettingMicrojetting at a solid surfaceat a solid surface

Prof. L.A. Crum, University of Seattle


Sonochemical Surface ModificationSonochemical 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 ModificationSonochemical Surface Modification Feasibility StudyFeasibility Study

Isola 370HR – Tg 180 ºC

Materials Tested

Cycolac S705 – ABS/PC

Noryl HM4025 – Polyphenylene ester / polystyreneCourtesy of Moulded Circuits

Ceramic Material


Sonochemical Experimental SetSonochemical Experimental Set--upup20 kHz Ultrasonic probe

Water in

Water out

Water Jacket

Solution

Sample holder

Sample

Thermostat

•All experiments performed at 40 ºC


Sonochemical Surface Modification Sonochemical Surface Modification –– ScreeningScreening

Effect of Ultrasound on Existing Surface Modification Processes

DI Water 400g/l Potassium Hydroxide

10% Sulphuric acid 5g/l AB42

10% Sulphuric acid, 5% Hydrogen peroxide 150g/l AB42

20% Nitric acid Alkaline Permanganate

20% Nitric acid, 40% Phosphoric acid 75ml/l Nitric acid, 27g/l Potassium permanganate

40% Phosphoric acid 20% Hydrogen peroxide

85% Phosphoric acid, 5g/l Potassium permanganate 27g/l Potassium persulphate

20% Ammonia, 40% Hydrogen peroxide 27g/l Potassium persulphate + 5g/l Ferrous Sulphate

8.2% Hydrochloric acid, 8.2% Hydrogen peroxide 4.1% Hydrochloric acid, 4.1% Hydrogen peroxide

•Reduce chemical concentrations

•Reduce process times

•Reduce temperatures


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 ModificationSonochemical Surface Modification Effect of Ultrasound on Existing Surface Modification Processes

Weight loss results for Ceramic Material

DI Water


Sonochemical Surface Modification Sonochemical Surface Modification OptimisationOptimisation

Sonochemical Surface Modification in DI water

Evaluate the effect of Sonication time on Surface Modification

Determine Efficacy by various surface analysis techniques

•Weight loss

•Contact Angle

•Roughness (Stylus profilometer)

•SEM


Sonochemical Surface Modification of Noryl HM4025Sonochemical Surface Modification of Noryl HM4025 Effect of Sonication time on weight loss

20 kHz Ultrasonics Horn, Power 33.5 W, 40 ºC, DI Water

0.0000

0.0500

0.1000

0.1500

0.2000

0.2500

0 10 20 30 40 50 60 70

Time (minutes)

Wei

ght L

oss

(mg/

cm2 )

As received

30 minutes sonication


Sonochemical Surface Modification of CeramicSonochemical Surface Modification of Ceramic Effect of Sonication time on weight loss


0.0000

0.0500

0.1000

0.1500

0 10 20 30 40 50 60 70Time (minutes)

Wei

ght L

oss

(mg/

cm2 )

As received

30 minutes sonication


Sonochemical Surface Modification of Sonochemical Surface Modification of IsolaIsola 370HR370HR Effect of Sonication time on weight loss


0.0000

0.0500

0.1000

0.1500

0.2000

0.2500

0.3000

0 10 20 30 40 50 60 70

Time (minutes)

Wei

ght L

oss

(mg/

cm2 )

As Recieved

30 minutes Sonication


Sonochemical Surface Modification Sonochemical Surface Modification –– Phase 2 Phase 2

Conclusions• Sonochemical Surface Modification of Isola 370HR, Noryl

HM4025 and Ceramic is possible in DI water• Degree of surface modification tends to increase with

sonication time• Little effect on ABS – some very localised surface

modificationFurther work• Optimisation of sonochemical parameters

– Power– Frequency– Viscosity


Sonochemical Surface ModificationSonochemical Surface Modification Scale-up

Surface Modification of a Ceramic

0.0000

0.0200

0.0400

0.0600

0.0800

5 minutes 15%HF Etch

5 minutes 150W 5 minutes 150W+ Surfactant

10 minutes150W

10 minutes150W +

Surfactant

Wei

ght l

oss

(mg/

cm2 )


Sonochemical Surface Modification Sonochemical Surface Modification –– Scale up Scale up

Work in progress….• Scale up appears to be feasible• Confirms that sonochemical surface

modification can be achieved in tap water• Weight loss significantly higher than HF etch• Adding a small amount of surfactant is

beneficial to the process• Need to optimise ‘jigging’ of material


Evolution of the Sonochemical Surface Modification ProjectEvolution of the Sonochemical Surface Modification Project

Concept

Use Ultrasound to Enhance existing surface modification techniques

Sonochemical Surface

Modification in water

Optimisation of sonochemical

paramaters

Scale up

Other Ultrasound techniques

Abrasive particles Sonoelectrochemical

Spin off projects


Sonochemical Surface ModificationSonochemical 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 DETAILSCONTACT DETAILS

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

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


Sonochemical Surface ModificationSonochemical Surface ModificationProject funded by

Industrial Partners

MOULDED CIRCUITS LTD

Laminate supplied by………


Thank youThank you

Any Questions ?

the sonochemistry centre - loughborough university...sonochemistry centre at coventry university...

Documents