1. July 2, 2007
ID CERN
S. Terada
KEK Module and Service Structure Designs -Super module conceptual design- - FEA thermal analyses- -Test of angled wire bonding- Japanese SCT group

2. Super module concept
Basic concept is to mount the modules on to cylinder
Fabricate and test individual modules
Thin module - front-back correlation
Overlapping geometry without sensitive gap
Failed module is replaceable
Make a row of modules into a unit with super-frame
Unit is testable with cooling loops included
Cooling might be required in both sides
Make the cooling pipe to slide so that the move of the pipe should not be transmitted to the module
Mass of the super-frame could be compensated with
elimination of dog-legs of the service harness
reduction the number of brackets - slender and one per two modules
Carbon-carbon cooling blocks instead of Al blocks
length of the cooling pipe is twice, but compensated with smaller diameter and no solder (of the cooling block)

3. Four hybrids/module, four connectors/module Square sensors (9
Four hybrids/module, four connectors/module Square sensors (9.754 cm x cm)

4. Two hybrids/module, two connectors/module

5. Hybrid - Conceptual layout

6. Hybrid-Service connection
Mass reduction in the connection
(1)Not to use a connector,two methods:
(a)direct soldering,no Al conductor
(b)wire-bonding,thick wire,with reinforcement
(2)Use a miniature connector,three methods:
(a)ZIF FPC-connector
(b)Low-profile PCB-PCB connector(a la PIXEL)
(c) Low-profile PCB-PCB connector(a la SCT)
Note:all are similar once a reinforcement piece is included
(3)Reduce the number of connectors
(a)4 connectors/module(2 connectors x2 sides)
(b)2 connectors/module(1 connectors x2 sides)

7. SuperModule

8. SuperFrame

9. SuperModule - expanded

10. End view at Z=0

11. End view at end

12. Bracket on cylinder

13. SuperModule on cylinder

14. SuperModule installation

15. FEA thermal analyses using ANSYS (2-dimensional calculation) • 0
FEA thermal analyses using ANSYS (2-dimensional calculation) • 0.1mm thick thermal grease around cooling pipe (2W/m/K) •Dead air between sensor and hybrid (0.024W/m/K)

16. sLHC 

17. Next step Calculation/estimation of the diameter of the cooling pipe
More realistic 3-D thermal and mechanical FEA calculations
Design of the service cables/harness
Number of traces, including DCS
Investigation of the connectors in industry
Minimization of parts
Tabulation of materials, comparison
Design of the hybrids
Manufacturing of the super-frame model for mechanical and thermal measurements
Optimization of 3rd mounting points

18. Test of Angled Wire Bonding
Company: HAYASHI Precision Electric Co., Ltd
Bonding machine: K&S8060
Wire: Al/Si(1%). ø25µm
Bonding tool: K&S　4WFM T6F-M00
Dummy sensor: ATLAS98, 80µm strip pitch
Dummy ASIC 55µm pitch Al. pad on Si. substrate
Level difference: 1.850.05mm
1st.Bond: Dummy ASIC
2nd.Bond: Dummy sensor

19. Test of Angled Wire Bonding
Test piece
L=3.3mm
L=4.3mm
L.D=1.85mm

20. Test of Angled Wire Bonding
Max. bonding angle
Dummy ASIC 1287.04mm
Dummy sensor 12810.24mm
(10.247.04)21.6mm
L=3.3mm  tan-1(1.6/3.3)25.9
L=4.3mm  tan-1(1.6/4.3)20.4

21. Test of Angled Bonding L1=3.3mm, L2=4.0mm Max. angle = 26°
Good loop shape
1st bond:　OK
2nd bond:  need to keep weld width to be narrower than 1.5 times wire diameter
2nd bond on sensor
1st bond on ASIC

22. Test of Angled Bonding L1=4.3mm, L2=5.0mm Max. angle: 20.4°
Good loop shape
1st bond:　OK
2nd bond:　OK
2nd bond on sensor
1st bond on ASIC

23. Test of Angled Bonding mean r.m.s. Pull values
All wires broke at the neck of the 1st bond

24. Test of Angled Bonding Sensor with 74.5µm strip pitch (ATLAS07)
ASIC 1287.040mm
Sensor 1289.536mm
(9.5367.040)21.248mm
Max. angle of L=3.3mm: tan-1(1.248/3.3) 20.7
Max. angle of L=4.3mm: tan-1(1. 248/4.3)16.2
Adding ASIC positioning accuracy of 0.2mm
1. 2480.21.448mm
Max. angle of L=3.3mm: tan-1(1. 448/3.3)23.7
Max. angle of L=4.3mm: tan-1(1. 448/4.3)18.6(L=4.1mm: 19.5)
 L=4.3(4.1)mm OK (less than 20.4)

25. Test of Angled Bonding Summary
Wire bonding of L1=4.3mm, L2=5.0mm, level diff.=1.85mm, max. angle= 20.4° was tested to be OK.
Considering a positioning accuracy of ASIC = 0.2mm, sensor strip pitch of 74.5µm (ATLAS07), taking a bond length of L=4.3mm, max. bonding angle becomes 18.6, or L=4.1mm, max. angle becomes 19.5.  OK (less than 20.4)
Width of the 2nd bond weld should be narrower than 1.5 times the wire diameter. (minimum=~1.2)