"AlSiC-Based Hybrid Composite Tool Kit"

By Richard W. Adams

and Mark A. Occhionero

Ceramics Process Systems

111 South Worcester St

Chartley MA 02712-0338

www.alsic.com

New England IMAPS 31 Annual Symposium

Thursday May 6, 2004

"AlSiC-Based Hybrid Composite Tool Kit"

• Abstract: AlSiC and multi-component structures provide unique

thermal management electronic packaging solutions for

microwave, microelectronics, power electronics, and

optoelectronics that result in improved product reliability. This

paper reviews volume AlSiC manufacturing applications today,

and then describes examples of a wide range of possibilities for

multi-component, multi-functional thermal management

structures.

AlSiC Packaging for Electronics Thermal Management- Basic Parameters

• Controlled Thermal Expansion

– Engineered CTE values - for component and assembly compatibility

= reliability

– Engineered solutions can create typical CTE values 7-12 ppm/°C

• Thermal Dissipation

– High isotropic thermal conductivity, typical = 200 W/mK

• Lightweight

– 3 g/cm3

• Cost Effective Manufacturing Capability - net shape cast

CPS AlSiC Fabrication - Defines Properties and Design

• SiC to Al-metal ratio defines thermal expansion– 1st - SiC preform with controlled and variable volume content– 2nd - Infiltrate with Al-metal to form the AlSiC composite

• Thermal conductivity determined by components– Electronic Grade SiC 230 - 260 W/mK – A356.2 Casting Alloy 160 W/mK– Little influence of ratio of 2 components

• net shape forming – preform is ~ smaller than final part– infiltration tool = final dimensions– eliminates costly machining

SiC preforminjection molded

AlSiC productinfiltration casting

AlSiC - Metal Matrix Composite Material

SiC

SiC particles uniformly distributed in continuous Al-matrix

~63 vol% SiC

~55 vol% SiC

~37 vol% SiC

See www.alsic.com

AlSiC Tools

• Marry Properties to Product Design

• Design Functionality

– Basic AlSiC

• lids

• baseplates

• package system structures

– AlSiC + Concurrent IntegrationTM

• Cooling Tubes - active fluid

• HOPG / Diamond - passive transfer

• Dielectric Ceramic Inserts - Ω isolation

Basic AlSiC Design

• Pick compatible AlSiC CTE

– Seal rings

– Substrates

– Devices

• Design rules for AlSiC casting

– Draft Angles

– Thicknesses

– Radii

– Al-Rich Areas for conventional

machining

See www.alsic.com

Basic AlSiC - lids

• Simple to Complex Geometries•Applications:

•Microprocessor Lids•DSP•Flip Chip Lids•Optical Lids

•Volumes•100 pcs - 40K/week

•Price (Volume/Complexity) • $ 2 - $ 5 in volumes of ~100K/yr

Basic AlSiC - lids

• Complex Geometries•Product is net-shape fabricated - no machining

•multiple pedestals•angled features•radial alignment features•septums and walls•lower cost than machined Aluminum alternative

Basic AlSiC - Baseplates

• Compatible CTE = unlimited

thermal cycling of package

– AlN soldered to AlSiC

• Design

– Dome Shape - Side 1

• Compressing a dome shape

against flat cold plate

maximizes heat transfer

– Flat - Side 2

• Attachment of “flat” substratesflat dielectric substrate surface

convex bow cooler plate surface

Thomas Schuetze, Herman Berg, Oliver Schilling “The new 6.5kV IGBT module: a reliable device for medium voltage applications”, PCIM September 2001

Concurrent IntegrationTM -High Density Interconnect (HDI) for GaAs Microwave Transmit/Receive Packages

First, dense dielectric ceramic ferrules are inserted into the QuickCastTM infiltration tooling along with the SiC preform.

Then, the Al-metal, that infiltrates the SiC preform to form the AlSiC composite, hermetically bonds and fills the ferrules to form coaxial feedthrus. This process is termed Concurrent IntegrationTM.

• Dielectric Feedthrus

Concurrent IntegrationTM - AlSiC LED Submount

• Alloy Metal Inserts•Product Features:

•multiple pedestals•angled features•partially machined to expose Alloy 49 pads for assembly•Alloy 49 bonded direct to Al phase of AlSiC

Alloy 49 pad

Concurrent IntegrationTM - Optoelectronic AlSiC TE Cooler Substrate with HOPG

• High Thermal Conductivity Insert

• Product Features:– Pyrolytic Graphite (PG) compressively

encapsulated within AlSiC

– Thermal conductivity 1300 W/mK

– PG located near heat source/TE cooler position.

• Selective use of costly material

1350 W/mK

Heat source surface

1350 W/mKAlSiC laser diode TEC substrate system showing TEC mount area (top) and the cross section showing the HOPG insert in the AlSiC composite (bottom).

HOPG 1300 W/mK

AlSiC

AlSiC

Concurrent IntegrationTM - Liquid Flow Thru Cooling

• Cooling Tube or Heat Exchanger

Product Features:• Tube intimate within AlSiC casting

– SiC overmolded onto tube

– Direct bond AlSiC to tube

– Maximize heat transfer AlSiC to tube

• Low cost one step assembly• CPS Patented process

Metallurgical Bonding AlSiC to AlSiC

BASE

TOP

Heat sink and housing are joined by Friction Stir Welding.

• Friction Stir Welding •Bonding of Engineered Al-Rich Areas within AlSiC casting

•Al Solder Bonding Processes•Various commercially available•Desired Al Skin Present on AlSiC

QuickCastTM High Pressure Precision Aluminum Casting

• Aluminum-only precision casting

– Tolerances in the +/-0.003” Range

– Low cost tooling

– Rapid product introduction and

moderate production rate

• Option for Concurrent IntegrationTM

– Diamond, PG, etc inserts

High Output LED light housing

• RV, Boats, Theater, Safety Lighting

Summary "AlSiC-Based Hybrid Composite Tool Kit"

• Basic AlSiC Properties coupled with Concurrent IntegrationTM

– AlSiC = Engineered CTE, Thermal Conductivity, Lightweight

– CPS AlSiC =

• Shape Complexity and Tight Tolerance - net shape

• Attractive Value Proposition for many (growing number) of Applications

• Concurrent IntegrationTM Presents Thermal Package Design Options - limited

only to your imagination

– AlN, ZTA, Al2O3, Si3N4 Substrates/Ferrules, etc.

– Stainless steel, alloy 49, Titanium inserts

– Tubes, Heat exchangers, welded pin fin coolers

– High Thermal Conductivity Diamond, PG

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