Metal Injection Molded Photonic Device Packaging

1
Metal Injection Molded Photonic Device Packaging

• Rob Linke
• MIMforms LLC

2
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

3
What is MIM?
4
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

5
Manufacturing Process

• Design of Component
• Tooling of Mold
• Injection Molding
• Debinding
• Sintering
• Optional CNC Machining
• Finishing/Plating

6
Compounding

• Components
• Metal powder
• Wax
• Polymers
• Goals
• Sufficient binder to fill all voids
• Uniform mixture

Metal powder at 100x D50 2-10 µm
7
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

8
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

9
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
10
Shrinkage in Sintering

• Green part typically shrinks 15 during sintering
• Density increases
• Strength increases
• Final mechanical properties attained

11
Post-Sintering Structure
3000x Magnification
12
CNC Machining and Plating

• MIM tolerances
• /- 0.5
• For features lt4.0 mm it is /- 0.02 mm
• CNC tolerances
• /- 15 µm
• Plating
• Gold
• Nickel
• Other

13
MIM Materials Kovar

• Photonic and optoelectronics packages which match
  CTE of borosilicate glass
• 29 W, 17 Co, 53 Fe
• Properties
• CTE (30-400oC) 4.4-5.2 ppm/ oC
• Density 7.95 g/cm3
• Density 97

14
MIM Materials Iron-Nickel

• Photonic and optoelectronics packages
• 50 Fe, 50 Ni
• Properties
• CTE 8.8 ppm/ oC
• Density 7.75 g/cm3
• Density - 95

15
MIM Materials Tungsten-Copper

• Heatsinks for photonic housings which mirror CTE
  of borosilicate glass
• 80W, 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

16
Tungsten Copper Structures
Infiltrated Tungsten skeleton with liquid Copper
Vacuum Sintered Tungsten-Copper powder
17
Why use MIM?

• Reduce or eliminate individual CNC machining
• Reduce material waste
• Enable mass production of intricate, highly
  detailed structures
• Reduce total cost

Kovar Lens Holder
18
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

CNC MIM
package cost ?
production volume ?
19
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

CNC MIM
package cost ?
shape complexity ?
20
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
21
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

22
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

23
Additional Information on MIM

• Organization
• CISP-Center for Innovative Sintered Products-Penn
  State
• Book
• Injection Molding of Metals and Ceramics German
  Bose