CCD Packaging Discussion

1
CCD Packaging Discussion
C. Baltay SNAP Collaboration Meeting June 7, 2005
2
CCD Module/Focal Plane Workshop
At Yale May 27, 2005

• CCD package
• NIR package
• Focal plate
• Connectors
• Assembly procedures
• Electronics front end
• Thermal structural
• issues of above items

3
The Focal Plane Mock -up

• Because development of the focal plane is seen to
  be a difficult task, we must show at proposal
  time that we are capable of doing it.
• We have to generate a design which addresses the
  major challenges of
• Mechanical mounting
• Thermal control
• Working within constraints of detector materials
  and vendor packaging systems
• Data interfaces
• Elimination of single point failure modes
• Stray light
• Contamination
• Accommodation of the spectrograph
• Ability to perform testing, integration,
  maintenance and rework
• We propose to fabricate a full scale focal plane
  mock-up to visibly demonstrate that we have
  solved the major design challenges

4
May 27, 2005 Meeting at Yale

• Attendees
• Berkeley H. Heetderks, C. Bebek, N. Roe
  (Telecom)
• Fermilab M. DeMarteau, T. Diehl, J. Fast
• Univ. of Michigan B. Bigelow
• Yale Univ. C. Baltay, W. Emmet, D.
  RabinowitzAgenda
• C. Bebek-Overall specifications, CCDs, IR
  detectors, Rockwell vs. Raytheon
• H. Heetderks-Engineering overview, choice of
  materials, etc.
• W. Emmet-2nd generation CCD package, assembly,
  etc.
• B. Bigelow-Infrared detector packaging, silicon
  carbide considerations
• J. Fast-Bump bonding
• Discussion
• Where do we go from here?
• Breadboards
• Who does what?
• and so on

5
Agreements and DecisionsSummarized by Henry
Heetderks

• The SNAP focal plane will be designed to
  accommodate RSC NIR, RVS NIR, and CCD detectors
  interchangeably in any location. To accommodate
  this, the unit cell pitch on the focal plane will
  be fixed at 45.52mm.
• LBNL will design a modified CCD of 3900 X 3900
  pixals to accommodate the 45.52mm pitch.
• The thickness of the cold plate will be between
  50mm and 75mm with the final value determined by
  Pat Jelinsky with FEM support from Robert
  Besuner.
• The baseline material for the design of the focal
  plane cold plate will be silicon carbide. The
  silicon carbide plate design will be carried
  forward until the design is complete or until
  substantial difficulties are identified at which
  time it may be decided to consider other
  materials (such as molybdenum).
• Two versions of the CCD and NIR modules will be
  designed one version will accommodate a silicon
  carbide cold plate, with the other intended for
  a molybdenum plate.
• We will hold another meeting of this group in
  approximately September at either FNAL or
  Berkeley (TBD).

6
Action Items and Near Term Activities

• Berkeley will
• Devote the Engineering Meeting on the last
  Thursday of each month to detector issues. The
  other weekly Engineering Meetings will
  concentrate on more general focal plane design
  issues.
• Continue layout and design of the focal plane
  mock-up with the intent of beginning fabrication
  within the next four months. Near term tasks
  include continuing thermal and mechanical FEM
  analysis of the cold plate to make a decision on
  the thickness.
• Continue review of material properties of silicon
  carbide as they impact the use of this material
  for the focal plane cold plate. Of particular
  importance is to determine definitive values for
  CTE at cryogenic temperatures for various SiC
  manufacturing processes. (Note that Pat Jelinsky
  believes that the SiC CTE information we are
  seeking is already included on Rev C of drawing
  00064 which was released on 2005-05-12. Select
  the Integrated Expansion tab on 00064-ME02-C.)
• Pat Jelinsky will send cryogenic information on
  Epotec 301-2 and Hysol 9361 which was measured at
  LBNL to Jim Fast. He will also add it to Rev D
  of 00064.

7
Action Items and Near Term Activities

• Yale will
• Design a total of 4 variations of the Version 2
  CCD module. All packages will mount via three M3
  screws in an isosceles triangle configuration
  with 35mm height and 31mm base. The dimensions
  of the mounting pattern may be changed by Pat
  Jelinsky working with other members of the
  collaboration. The Yale designs will include
  bump bonded and wire bonded versions and versions
  which attach to silicon carbide and to molybdenum
  cold plates.
• Refine FEM study of various insert geometries to
  include epoxy in the Ikea design, and to load
  the block in which the insert is mounted in the
  way it would be loaded when mounted on an actual
  focal plane cold plate.
• Manufacture a 3X3 block of 9 unit cells for
  evaluation mounting of the various detector
  module configurations.
• Manufacture a full scale mock-up in aluminum of
  the cold plate made to the geometry of the
  silicon carbide plate.

8
Action Items and NearTerm Activities

• Fermi National Accelerator Laboratory will
• Review analysis of polymeric back fill of CCD
  bump bonded to aluminum nitride circuit board.
  Research and establish cryogenic properties of
  Epotec 301-2 and Hysol 9361.
• Evaluate other polymeric systems which may be
  used for back fill, particularly cryogenic
  properties.
• Set up system to make cryogenic flatness
  measurements of CCD and NIR detectors for SNAP.
  System should handle both Yale Version I CCD
  modules as well as the version 2 units which will
  be packaged in the baseline flight configuration.
• Set up a thermal cycling test of the Version 1
  CCD which will be delivered imminently by Mike
  Lesser.
• Jim Fast will send bump bonding information to
  Chris Bebek at LBNL. (I didnt quite understand
  what the issue is here. hdh)

9
SNAP 4-Side Buttable CCD Design

• Sectional View

10
Thermal Expansion Data for SNAP CCD Candidate
Packaging Materials
11
SNAP 4-side Buttable CCD Finite Element Analysis

• Isometric View of Deformation in Z-axis (Invar
  36/Aln Package)

12
SNAP 4-Side Buttable CCD Design

• Aluminum Nitride Substrate-Top View

13
SNAP 4-Side Buttable CCD Design

• Aluminum Nitride Substrate-Bottom View

14
SNAP 4-Side Buttable CCD Design

• Circuit Board-Bottom View

15
SNAP 4-Side Buttable CCD Design

• Circuit Board-Top View

16
2nd Generation Package
Bump-bonded with Invar 36 mounting foot
molybdenum interface (Hypertronics connector)
17
2nd Generation Package
Bump-bonded with Silicon Carbide mounting
foot (Hypertronics connector)
18
Area-matched CCD packages
Raytheon
Rockwell SNAP V2
Keep 10.5 µm pixels in both cases
19
Wire-bonded Package (contd)
We have some experience with this type of
packaging (QUEST project)
20
Wire-bonded Package (contd)
Wire-bonded with Invar 36 mounting foot (contd)
Detail of wire bond cavity
21
Wire-bonded Package
Larger device size leaves more room for
wire-bonds (see Bebek Holland Report on SNAP
v3 CCD Effort and Risk 5-May 2005)
Wire-bonded with Invar 36 mounting foot (SiC
could be substituted)