Thoughts about PS module assembly Ulrich Heintz, Meenakshi Narain, Bill Patterson, Eric Spencer, Juan Trenado Brown University, Providence 4/16/2015Heintz, Narain, Patterson, Spencer - PS Assembly 1

PS module 4/16/2015Heintz, Narain, Patterson, Spencer - PS Assembly 2 Assume electronics hybrids are preassembled Focus on sensor and base plate assembly

Components of PS module 1. CF base 2. P sensor assembly Consists of P sensor, bump-bonded readout chips, spacers glued to readout chips. Assume that alignment targets on the four corners of the P sensor are visible from the top. 3. S sensor Assume that there are alignment targets on all four corners of the S sensor 4/16/2015Heintz, Narain, Patterson, Spencer - PS Assembly 3

Assembly sequence Mount electronics hybrids after gluing sensors to CF base ROICs protrude beyond sensor/spacer preventing insertion of sensor into a preassembly of CF base + electronics hybrids Hybrid spacer and sensor spacer need to be glued together Is support of bottom sensor/ROIC good enough for wire bonding? 4/16/2015Heintz, Narain, Patterson, Spencer - PS Assembly 4

Assembly sequence Why not like this? Alan suggested the following to simplify hybrid spacer design plus some protrusions to make contact with sensor spacer 4/16/2015Heintz, Narain, Patterson, Spencer - PS Assembly 5 The dimensions of the sensors precisely fit inside the useful area of a Si wafer. Increasing the dimension in length direction would require reducing it in the width which reduces the acceptance of the module. Not much overlap between neighboring modules and larger gaps. Suspect this statement is based on 6” wafers?

Assembly sequence Glue spacers to top sensors Maybe use similar procedure being developed for 2S modules Allows us to pull silicon sensor flat with vacuum chuck How to define position of spacers? We are working on some ideas… 4/16/2015Heintz, Narain, Patterson, Spencer - PS Assembly 6

Assembly sequence Glue bottom sensor to CF base plate Apply uniform pressure to bottom sensor when gluing it to CF base How flat is the bottom silicon? How coplanar are the surfaces of the ROICs? How good are the edges of the ROICs? How much pressure do we need? How much pressure can we apply w/o breaking ROICs or bump bonds? There are no prototypes yet so we don’t know. Do sensor and CF base have to be electrically isolated? How? Yes. The plan is to cover the CF base with parelene. What are the specs for the glue? How to apply it? No specs yet. Maybe use glueing stamp (ala FPIX phase 1) avoid bubbles over the large area? 4/16/2015Heintz, Narain, Patterson, Spencer - PS Assembly 7

Assembly sequence Glue top sensor/spacers to bottom sensor/ROICs Use vacuum chuck to flatten silicon Apply pressure to spacers to squeeze glue joints It might be useful if we can see alignment marks on both sensors simultaneously Could the bottom sensor be a little longer than the top sensor? Raises the same acceptance problem as changing the size of top sensor 4/16/2015Heintz, Narain, Patterson, Spencer - PS Assembly 8 Vacuum chuck

Assembly stage 4/16/2015Heintz, Narain, Patterson, Spencer - PS Assembly 9 Linear stage ≈ 6 inch travel in x Pins to position CF base Vacuum to pull down CF base x y z Linear stage travel in z Fine adjust in y Fine adjust in Vacuum to pick up sensors Weight to apply pressure to glue joints

Assembly stage 4/16/2015Heintz, Narain, Patterson, Spencer - PS Assembly 10 Microscope  6 inch travel in x Relative alignment of sensors x y z

Step 1 Load CF base assembly and align using pins so that CF base is aligned with x direction 4/16/2015Heintz, Narain, Patterson, Spencer - PS Assembly 11

Step 2 Load bottom sensor/ROICs Maybe initial alignment using edges Fine align using microscope and y/ adjustments in pickup 4/16/2015Heintz, Narain, Patterson, Spencer - PS Assembly 12

Step 3 Apply glue to CF base Move base under sensor Align in x with linear stage Lower sensor onto base Use weight of sensor pickup to compress glue joint 4/16/2015Heintz, Narain, Patterson, Spencer - PS Assembly 13

Step 4 After glue has cured lift vacuum pickup Move assembly from under pickup 4/16/2015Heintz, Narain, Patterson, Spencer - PS Assembly 14

Step 5 Apply glue to bottom of spacers Load top sensor/spacers (with spacers facing down) Maybe initial alignment using edges Fine align using microscope and y/ adjustments in pickup 4/16/2015Heintz, Narain, Patterson, Spencer - PS Assembly 15

Step 6 4/16/2015Heintz, Narain, Patterson, Spencer - PS Assembly 16 Move base under sensor Align in x with linear stage Lower sensor onto base Use weight of sensor pickup chuck to compress glue joint It might be useful if we can see alignment marks on both sensors simultaneously

Conclusion First thoughts on assembly sequence and alignment procedure for PS module Fixtures should not be too expensive It should be possible to automate alignment procedure with pattern recognition software Plenty of questions… We will start to try out some steps in this sequence 4/16/2015Heintz, Narain, Patterson, Spencer - PS Assembly 17