Contact materials at elevated temperatures. High Temperature Electronics

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Agenda

Introduction

Soft Solder Alloys

Sintering

HotPowCon (HPC)

Summary

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Assembly of a power module

Introduction

Requirements:

High power density

High reliability

High heat Conductivity

Ambient condition more than 150

°

C

Lead Free technology

Live time more than 15 years

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Soft Solder Alloys

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Speziallegierungen für Weichlote: Innolot

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Speziallegierungen für Weichlote: Innolot

Seite 6 J. Trodler | Heraeus Materials Technology CMD-AM | 06.12.2012

SPEZIALLEGIERUNGEN FÜRWEICHLOTE

Source: Abschlusspräsentation BMBF-Projekt LIVE; Akzeptanzkriterien thermisch hochbelasteter,

miniaturisierter Lötverbindungen; J. Albrecht Siemens AG, CT MM6; Berlin 17.9.2008

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Special Soft Solder Alloy: HT1

Cross section after powder

production (source: Müller,

NMB 160804)

Mapping of the powder;

figure b) Ag (=Ag3Sn)

(source Müller, NMB,

160804)

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Special Soft Solder Alloy: HT1

a) SAC + In (without modifier) and b) SAC+In+KM (source Müller, NMB, 160804)

a)

b)

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Cross Section with 3,75% Ag, Ag3Sn

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Melting Range (Liquidus and Solidus)

Special Soft Solder Alloy: HT1

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Technology Qualification TCT 30’/10’’/30’@-40/+175 N=500

SnAg3.5

HT1

Innolot

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CS N=3000 SnAg3.5

CS N=2000 SnAg3.5

CS N=1500 SnAg3.5

CS N=1500 HT1

CS N=4000 HT1

Source: Dudek, Fraunhofer ENAS

Product Qualification TCT 30’/10’’/30’@-40/+125 N=1500/2000/3000/4000

Special Soft Solder Alloy: HT1

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Table with the most important properties

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Sintering: Processing mAgic 016

Items

Items

Process Equipment Parameter

Paste Application

Paste Application

Stencil printing convetional printing equipment •Stainless steel or PU squeegees •Print Speed 30-70 mm/s

Paste Drying

Paste Drying

Drying of printed sinter paste Conventional Box oven

•Drying time 5-15 min •drying temperature 60-120°C •Drying in air

Die Placement

Die Placement

Placement of die

Die placemer with heated substrate

holder

•Die Placement temperature 80-130°C •Die Placement force min

0.03 MPa

Sintering

Sintering

Sintering Step Sinter press •Sinter Pressure 20-40 MPa •Sinter Temperature 230°C-280°C

•Sinter time 1-2 Minutes in air

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Sintering: Processing mAgic 016 with DIE size 100mm²

Items

Items

Process Equipment Parameter

Paste Application

Paste Application

Printing/Dispensing Standard equipment •Standard Parameter

Die Placement

Die Placement

Placement of Die

Standard Die placer

Standard die Placement Parameter

Sintering

Sintering

Sintering Step

Box Oven

•Peak Sinter Temperature 230°C-280°C

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Thermography

Sintering

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HotPowCon

Laufzeit 05.2011 – 04.2014

FKZ 13N11510

Coordination: Robert Bosch GmbH

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Diffusion Soldering HPC

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Investigation of thermo/mechanical reliability by experiment and simulation,

source: Fraunhofer ENAS

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Diffusion Soldering HPC

Combination of thermal solidification and isothermal solidification could be the

basis for a new quality of interconnection

Phase diagram of a two element

system

Creating of intermetallic with Cu in a SnCu

system. (Source: Fraunhofer IZM)

• Structure design through high melting intermetallic by using soft solder alloys based

on solder paste

• soft solder alloy will be used based on Sn with a high metal concentration and

additives

• Isothermal solidification at low/standard solder temperatures

• operation temperature higher than liquidus temperature after soldering

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Diffusion Soldering HPC

Combination of thermal solidification and isothermal solidification

IGBT on DCB with SnCu solder

paste (type 6) produced with a

20µm stencil

IGBT on DCB with SnCu solder

paste

(type

6)

and

Cu

powder

produced with a 20µm stencil

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Diffusion Soldering HPC

Workpackage and Milestones

Design

Process

Test &

Simulation

WP2

WP3

WP4

Materials

Application

WP1

• M1 describes a combination of materials

as well as the realization of that

combination based on a lab application

• M2 has fixed the processes including a

qualification of test equipment.

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Diffusion Soldering HPC

Results DMA

-0,05 0 0,05 0,1 0,15 0,2 0,25 140 240 340 440 C h a n g in g o f le n g th [r a ti o ] Temperatur [°C]

DMA with Cu particles Q1and SnCu

reference, after soldering. There is no

-0,05 0 0,05 0,1 0,15 0,2 0,25 150 200 250 300 350 400 450 C h a n g in g o f le n g th [r a ti o ] Temperatur [°C]

DMA with Cu particles Q2and SnCu

reference, after soldering the

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Summary

FEM: By the local damage-parameter D

(read area 0,96 < D < 1 = delaminated)

it shows a delamination at the corner

of the Die. Means the delamination starts

at app. -35

°

C.

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• Soft Solder Alloys up to 175

°

C depends on the

assembly concept

• Sintering already use for industry applications,

different project for optimization (minimization)

process temperature and pressure

• Government founded project: HotPowCon (HPC) as

alternative for higher operation temperature > 300

°

C

in project progress

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~ 1000

°

C Sintering (process temperature 220

°

C)

~ 400

°

C HPC (process temperature 227

°

C + 20K)

~ 300

°

C High Lead solder (process temperature + 20K)

~ 220

°

C Lead Free solder (process temperature + 20K)

Summary

Figure

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References

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