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

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)

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

Two hybrids/module, two connectors/module

Hybrid - Conceptual layout

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)

SuperModule

SuperFrame

SuperModule - expanded

End view at Z=0

End view at end

Bracket on cylinder

SuperModule on cylinder

SuperModule installation

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)

sLHC 

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

Test of Angled Wire Bonding Company: HAYASHI Precision Electric Co., Ltd Bonding machine: K&S8060 Wire: Al/Si(1%). ø25µm Bonding tool: K&S　4WFM6-2015-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

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

Test of Angled Wire Bonding Max. bonding angle Dummy ASIC 0.0551287.04mm Dummy sensor 0.08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

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

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

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

Test of Angled Bonding Sensor with 74.5µm strip pitch (ATLAS07) ASIC 0.0551287.040mm Sensor 0.0745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)

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)