sLHC Stave Wire-bonding Clearances (Tim) WP4 Glasgow (13 th June 2011)

Overview Recent developments in stave mounting mechanisms and move towards lower tilt angles means space for locking mechanisms is more restricted. Current work-around is to dog-leg the locking mechanism. Impact for stave construction is that dog-legged locking mechanism locally increases stave thickness and globally increases stave frame thickness What is the impact on wirebonding?

Assumptions Consider issue to only be relevant for ABCN13 module geometries i.e. – Two hybrids with single rows of 256 channel ASICs ‘Current’ locking mechanism geometry – Length 20mm – Height = 22mm from stave mid-plane Wire-bonding mechanisms – Complicated issue Machine dependent Look at some photos!

H&K 710M 20mm 15mm

Movement During wire bonding – Working height ~ 108mm – Transducer ~ +15mm (123mm) Transducer may spin round so all components should be lower Before / after wire bonding – Height ~ = 120mm Park and Wire Feed – (Vector) movement from arbitrary X,Y,Z=120mm to pre-defined positions:- Park: back / right Wire feed:front/right

Operating Areas & Modes Nominal Job Height

Wire Feed Access needed to thread wire Operator likes to clear job to minimise risk to component Use of tweezers to feed wire Upward illumination needed Hard to accomplish if wire feed position is within frame boundary

Transducer Movement Circle During wire bonding the whole head may need to rotate – Not clear that the XY position where this happens can be defined. Therefore need to define an exclusion radius – Estimate from photos of 65mm 15mm 65mm

Stavelet Wirebonding

Current Module / Tape Interfaces All wire-bonding is in the ‘longways’ direction Typical gaps are:- – Power side: 35mm – I/O side:20mm Width of jaws ~20mm at 15mm height – Limits proximity of wire-bond field to high edge component

Current Stave(let) If all components lie within +/- 15mm of the centre-line of the stave then there should be no problems with wirebonding. – The job can probably be set up so that wire-feed takes place outside the frame – Would need a well controlled stave mounting / removal mechanism to avoid transducer/wedge damage – Might work for dog-leg locking mechanism if barrel part is glued after wire bonding (15.6mm)

ABCN13 Modules Two hybrid fingers each with a single column of ASICs – Choice of hybrid layout:- Identical hybrids Symmetric hybrids – Inboard – Outboard Hybrids are within outer dimensions of silicon wafers – Wire-bonding area is behind 1 st /10 th FE-ASIC Wire-bonding is – Always transverse to the stave – Excluded either side of the locking points within 12mm

ABCN13 Module Wire-bonding

ABCN13 Conclusions (Preliminary) Lack of available length between bonding fields means it’s unlikely to be able to have identical hybrids – Maybe an issue for the module builders ? Ease of access/viewing suggests that transducer should always be at the rear – Locking points must be at the front IF we are OK to dismount (or lower by 60mm?) the stave to ease wire feed then the frame can be thicker by up to 2 x 13mm (56mm total thickness) before the bellows would foul provided the frame is extended to ensure the transducer movement circle clearance Could also consider developing jigging which defines bonding area to be between ‘park’ and ‘wire feed’ – should avoid all clashes – Preference for in-board hybrids?

220 x 175mm bonding area Programme for 1 or 2 modules Clear path from any XY point to PARK and WIRE FEED

H&K mm