17/06/2010uk valencia ral petals and staves meeting 1 dc-dc for stave bus tapes roy wastie oxford...

17/06/2010 UK Valencia RAL Petals and Staves Meeting

1

DC-DC for Stave Bus TapesRoy Wastie

Oxford University


2

Stave Overview

Carbon Fibre foam core plank

Module

Stave module controller

Cooling pipes

Size 1.2 m x 12cm 12 modules per side each with 2 hybrids


3

Stave Detail

Bus tape

Silicon Detector

ABCN chip

Hybrid flex PCB


4

Bus tape

Tape stack up

100μm track & gap


5

Stavelet

• Module evaluation

• Two types

• Segmented shield

• Solid shield


6

Layout Details

Serial Power Return

HV

Serial In

Power protection control

Wire bond pads

TTC busDataNTC


7

Openings for Bonding

150um

0.35mm & 0.65mm for HV pad

Kapton

Kapton

Kapton

Al

Copper pad

Adhesive

Wire bond

4 masks required one for Al screen, one for Copper tracks and two cover layers


8

Bus Cable Geometry and Impedance

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1~10.7

1

2

CF

Cu

ADHESIVE

KAPTON

Materials: Al foil 2mil, Dupont LF0100, Shinetsu CA333 2 mils, Cu 18 um,Kapton 1 mil, Adhesive

Al


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In house tape prototyping

• Thermal resistance– High conductivity glue layers

• Less material ie thinner Aluminium/kapton design– Aluminium 25μm on kapton 25μm for

screen layer and 50 μm Al for track layer– Hatched screen to reduce material– Easier to handle

• Rapid prototyping possible


10

Stave09 and DCDC Powering – moving forward

2.Integration of DCDC onto a Stavelet (shortened 4 module stave), what we presently have:

•Stavelet Bus cable is (presently) designed for serial powering •DCDC can be added, via the Power Protection Board drop-in connector, BUT is not ideal

•No DCDC power feed – it comes external to the Bus cable•Drop-in connector is multi-functional – used for other serial powering topologies (SPi, …)

•Not electrically optimised for DCDC•No ‘real estate’ available to integrate DCDC directly onto present Serial powered Stavelet

•The Power Protection Board is in the way!•No access to Stave cooling contact.

Propose designing a Stavelet Bus cable exclusively for DCDC

•Remove ALL serial powering trace routing from layout – freeing up space for DCDC requirements•Power feeds to converters and control could maybe integrated onto cable

•Revisit Bus cable shielding, currently 2 flavours exist:•Segmented – each module has it’s own individual shield (shields float w.r.t. each other)•Continuous – no segmentation (maximal coverage) with modules AC-coupled to shield•Optimise for DCDC…

BUT

•The geometry of the Stave will remain the same at 500mm x 120mm – fixed by tooling.•Availability of real estate for DCDC placement is still at a premium

Slide from Powering meeting CERN 30/3/10 Ashley Greenall


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Stavelet Geometry – ‘real estate’ for DCDC

Available space per module for locating DCDC components(typically ~97.5mm x 6.2mm)



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Stavelet – Bus cables

•Bus cable routing is on a single layer – no crossovers of traces allowed (no vias used!)•Build is 18µm Cu with 50µm Kapton dielectric

•Expect majority of routing to stay as is e.g. Data I/O, HV distribution etc.•But Serial Power Return and associated control can be removed.

Data I/O (remains)

Serial Power Return (not needed)

HV (remains)

Available for DCDC (6.2mm wide)

•Bus cable shielding, 2 flavours exist:

Flexes are DC connected to their respective shield

Flexes are AC connected to the shield

Segmented Continuous

120

mm

• Insufficient Cu for DCDC power feed and return?• 6mm trace width of 18µm Cu: <6A• Need 2 traces for DCDC powering…• Consider selectively adding more Cu (35µm)

• Move DCDC powering off Bus cable to PCB?• If so, could we still use existing Bus cables?



13

DCDC Powering Implementation for stavelet

Redesign CERN DCDC PCB to fit on to the stave bus tape connect with wire bonding. Limited to 6.2mm wide. Requires a narrow multilayer flex tape to bus the power in. DCDC PCB to tape and let it overhang, will need cooling ( add ceramic base board).

2mm side by side track single layer copper 105µm thickness

6.2mm

CERN DCDC PCB


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CERN DC-DC convertor

DCDC PCB

Hybrid outline

Serial power track green

sensor outline

DCDC power track red


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Full Stave DCDC• With 130nm, will the power system be able to tolerate power

dissipation and volt drop for 24 hybrid?• Too long for one DCDC narrow PCB, would require two.

(Flex/ridged) 105µm copper thicknessStavelet tape voltage drop & power

17/06/2010uk valencia ral petals and staves meeting 1 dc-dc for stave bus tapes roy wastie oxford...

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