Rob Linke, MIMforms LLC - Slide 1
Metal Injection Molded Photonic Device Packaging
Rob LinkeMIMforms LLC
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Outline
1. Metal injection molding defined
2. Manufacturing process
3. Materials for photonics packaging
4. Benefits of metal injection molding
5. Future directions
6. Conclusions and resources
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What is MIM?
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Metal Injection Molding
Utilizes wealth of technology developed for plastic injection molding
Injection molding of metal powder compounded with binder (plastic/wax)
Debinding of component (solvent or thermal) Sintering of part to final density
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Manufacturing Process
Design of Component Tooling of Mold Injection Molding Debinding Sintering Optional CNC Machining Finishing/Plating
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Compounding
Components Metal powder Wax Polymers
Goals Sufficient binder
to fill all voids Uniform mixture Metal powder at 100x
D50 : 2-10 µm
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Injection Molding
Virtually identical to plastic injection molding
“Feedstock” is molded at low temperatures (150oC) with consistency of toothpaste
Consists of metal powder in binder matrix (~ 40% binder by volume)
Yields “green” part
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Debinding
Binder removal from matrix (disposable component)
Solvent – water or other solvent Thermal decomposition Results in structurally weak
component with small amount of binder remaining
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Sintering
Sintering densification increases the atomic bonds between particles
Temperature is near melting point
Density of up to 98.5% Real world example –
ice cubes sticking together in freezer
Sintering Furnace
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Shrinkage in Sintering
Green part typically shrinks 15% during sintering
Density increases Strength increases Final mechanical
properties attained
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Post-Sintering Structure
3000x Magnification
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CNC Machining and Plating
MIM tolerances +/- 0.5% For features <4.0 mm it
is +/- 0.02 mm
CNC tolerances +/- 15 µm
Plating Gold Nickel Other
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MIM Materials: Kovar®
Photonic and optoelectronics packages which match CTE of borosilicate glass29% W, 17% Co, 53% Fe
Properties CTE (30-400oC) 4.4-5.2 ppm/ oC Density – 7.95 g/cm3
% Density – 97%
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MIM Materials: Iron-Nickel
Photonic and optoelectronics packages50% Fe, 50% Ni
Properties CTE – 8.8 ppm/ oC Density – 7.75 g/cm3
% Density - 95%
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MIM Materials: Tungsten-Copper
Heatsinks for photonic housings which mirror CTE of borosilicate glass
80%W, 20% Cu as Example
Properties CTE – 7.4 ppm/ oC at 50oC Themal Conductivity – 189 W/m K Density – 14.89 g/cm3
% Density - 95%
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Infiltrated Tungsten skeleton with liquid Copper
Vacuum Sintered Tungsten-Copper
powder
Tungsten Copper Structures
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Why use MIM?
Reduce or eliminate individual CNC machining
Reduce material waste Enable mass production of
intricate, highly detailed structures
Reduce total costKovar Lens Holder
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Machine Once or Many?
CNC machining Each part is machined
to final shape individually
MIM The mold is machined
once and parts are molded to final shape
production volume ►
package cost ►CNCMIM
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Shape Complexity
CNC machining Each detail adds to
cost (and time)
MIM Details are machined
into the mold – once Reproduced in each
package during molding shape complexity ►
package cost ►CNCMIM
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Material Waste Reduction
CNC removes large amounts of metal to yield housing
MIM uses only metal necessary
75% waste reduction typical
Runners, gates can be recycled on-site
Material waste with CNC Machining
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Future Directions
Complex designs specifically for MIM manufacturing
Custom MIM alloys/mixtures Higher dimensional tolerance
MIM components Increasing adoption of MIM
package use in North America
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Conclusions
MIM can be an enabling technology for photonic and optoelectronic packaging
Mass production Low/no cost structures Reduced material waste Designs not possible or economical with
CNC machining Greater alloy flexibility through batch
compounding
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Additional Information on MIM
Organization:CISP-Center for Innovative Sintered Products-Penn State
Book:Injection Molding of Metals and Ceramics German & Bose