Bucharest International Technical Fair TIB 2010, 36 edition, October 6-9, 2010 Mechanical Test...

Bucharest International Technical Fair

TIB 2010, 36 edition, October 6-9, 2010

Mechanical Test Assessment for Electronic Modules Able to

Function in Harsh Conditions

The 3rd International Symposium on Electrical and Electronics Engineering, 16-18 September, Galati, Romania

I.Plotog, G.Varzaru, P. Svasta

Vapor Phase Soldering Technology, a response for Innovative IMM Requests to

Lead–Free Era ChallengesI.Plotog, G.Varzaru, P. Svasta



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ContentsIntroductionCritical Mass outbreak of Innovation ProcessLead-Free Soldering Challenge

VPS technologyBasicsEquipments facilities

Applications

Conclusions

Acknowledgment

References



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Introduction:Introduction:Critical Mass outbreak of

Innovation Process



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Critical Mass outbreak of

Innovation Process

Human Factors Knowledge

Catalyst: Socio-Economic & Financial

environment

Economic development with broad social implications

Competitiveness through competence



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Innovation

EducationKnowledge

Practice

Theory

Industry

Inventors & Innovative SME

Cri

tic

al M

as

s o

f p

eo

ple

an

d S

ME

s

by

incr

eas

ing

th

e c

om

pe

ten

ce

UPBCETTI-ITA

Actions



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Assembling Workshop



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8



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Introduction:Introduction: Lead-Free Soldering Challenge



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Solder Paste

Pad NiAu, OSP, Ag-Im, HAL, Sn-Im

Solder joints

4P Soldering Model = 4 terms involve PASTE-PAD-PIN-PROCESS

Soldering Process

Thermal profile

Electronic

components



Lead-Free Soldering Process

Lead/Lead-Free Thermal profile



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Large dispersion for temperatures at PCB surface with consequences over solder joints microstructure



Thermal problemsTemperatures exceeding 230°C drastically increase the risk of thermal damages of the board and the electronic components

Popcorning

Cold Solder Joint (L-leaded package)

Cold or unsoldered solder joints

Limited temperature induction increases the risk of insufficient heat transfer especially on hidden solder joints (Shadowing effect)

Temperature

Cold Solder Joint (BGA ball)

Thermally overheated BGA ball

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Non Wetting of BGA ball

Non Wetting of L-leaded package

Wetting problemsReduced wetting properties of lead-free solders usually require a protective gas atmosphere during the soldering process

N2 coverage

Bad Wetting of rectangular component

Bad Wetting of L-leaded package

Higher process cost due to protective gas

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Increased overall machine length

To avoid solder cracks by enabling a smooth temperature ramp up the overall soldering track is further increased

Increased energy costHigher temperatures, larger machines, along with increased requirement for protective gas increases the already high energy requirements even higher

Increased ReworkHigh temperatures increase the risk of severe damage to the board. Solder and wetting problems, popcorning and others increase the production cost.

Hot Air Rework Process of BGA

T >> 250°C

Convection Vapour Phase

Power consumption

Depending on system

11 - 20kWh0,8 - 5,5kWh

Max Power consumption

Depending on system

>>20kWh1,8 - 10,4kWh

Solder Crack in L-leaded package

Solder Crack in J-leaded package

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Consequences: Increased temperature Poor wetting More voiding More oxidation Worse cosmetics Smaller process window Large temperature dispersion at PCB level with important modifications of the solder joints microstructure and in consequence over quality and reliability



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VPS technology:Basics



The heat transfer rates are much higher in condensation (Vapour Phase) than in convection.

Overview: Condensation (Vapour Phase) and Convection

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Vapour phase:A boiling fluid is creating a vapour blanket. The temperature is physically limited by the boiling point of the fluid. The electronic units are moved into the vapour, which is condensing at the (colder) electronic units. Convection:Heating elements in combination with blower motors are creating various hot air zones (forced convection). The electronic units are moved through the zones on a conveyor.

Heating elements with different temperatures

Conveyor Air at 175°C - 300°C

Air at 175°C - 300°C

Overview:Basic Vapour Phase

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Air

Process fluid

Vapour

Water Cooled Housing

Circular Water Cooling

Condensing Fluid

50-80°C

230-240°C

230-240°C

Standby

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Air

Process fluid

Vapour



Condensing Fluid

50-80°C

230-240°C

230-240°C

Cold Board Enters Vapour Phase System

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Air

Process fluid

Vapour



Condensing Fluid

50-80°C

230-240°C

230-240°C

Board at Soldering Temperature

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1.

2.

3.4.

5.

Soft Vapour Phase movement

Vapour Phase thermal profiling

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VPS technology:VPS-Convection process comparison



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VPS technology:Equipments facilities



The VPS equipment and facilities

The VPS equipment IBL company: SLC309

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Vacuum applications in VPS- IBL equipment Vacuum zone



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VPS Technology and Applications

Applications



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PCB with Different Core Materials



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Pin-In-Paste (a.k.a. Alternative Assembly and Reflow Technology, AART, and reflow soldering of

through-Hole, ROT)



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High thermal resistance

Lower thermal resistance

• Thermovizion analyzes



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CONCLUSIONSCONCLUSIONS Electrical & thermal parameters depend by all P

“actors” of the 4P Soldering Model; The Process influence significant the solder

joints reliability; VPS soldering process contribute to the

component thermal stress reduction (30°C maximum difference);

VPS offer lower peak temperature & lowest ΔT; Vapour Phase soldering is an ideal solution for:• Increased Quality• Economical Production• Energy Saving



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AcknowledgmentAcknowledgment

This paper represents the result of work done for promoting innovative technologies in the frame of INOINDEX project (CNMP: 91-002/2007). The authors are very grateful to the leading staff of IBL-Löttechnik GmbH for continuous support and collaboration to fulfill experiments used in the presented paper.

Many thanks from the authors to: -Cookson Electronics which offered the solder pastes for experiments, -FELA Leiterplattentechnik GmbH, the company that supplied the glass and metal core PCBs for experiments.



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ReferencesReferences

[1] R. Strauss, SMT Soldering Handbook, Butterworth-Heinemann Linacre House, Oxford, 1998, ISBN 0 7506 35894, pp. 179-189

[2] P. Svasta, I. Plotog, T. Cucu, A. Vasile, A. Marin, 4 P Soldering Model for Solder Joints Quality Assessment, ISSE 2009,The 32nd International Spring Seminar on Electronics Technology, 13-17 May, Brno, Czech Republic proceedings ISBN 978-80-214-3874-3.

[3] I. Plotog, P. M. Svasta, N. D. Codreanu, T. C. Cucu, C. Turcu, G. Varzaru, VPS Solution for Lead-Free Soldering in EMS Industries, ESTC 2008: Vol. 1, 2, Proceedings Pages: 121-124, London 2008

[4] I. Plotog, P. M. Svasta, N. D. Codreanu, T. C. Cucu, G. Varzaru “Investigations on Assembling of Electronic Packages onto Glass Substrates using Lead-free Technology”, 31st International Spring Seminar on Electronics Technology, ISSE 2008, Budapest, Hungary, May, 2008, Conference proceedings, pp. 415-419.

[5] H. Leicht, A Thumm, Today's Vapor Phase Soldering. An Optimized Reflow Technology for Lead Free Soldering, IBL-Löttechnik GmbH, www.ibl-loettechnik.de, Germany

[6] FELAM Thermoline, „Technical Documentation“, FELA Leiterplattentechnik, 2007.



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Mechanical Test Assessment for Electronic Modules Able to Function in Harsh Conditions

Ioan Plotog

Senior researcher, Executive Director, Technological and Business Incubator, CETTI-ITA Center for Technological Electronics and Interconnection Techniques, UPB-CETTI“Politehnica” University of Bucharest, UPBSpl. Independentei 313, sector 6, 060042Bucharest, Romania Tel: +40 21 4103108; +40 21 4024650Fax: + 40 21 4103118Email: [email protected]://www.cetti.ro/ita

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