January 13, 2004


Notes from Tracker Summit in Pisa


Ronaldo – introductory remarks.

Robert Johnson – revised agenda.

Dick Horn – Overall LAT project.

-        2/07 launch

-        Lehman review at the end of March.

-        Added Dave Rich, primarily as MCM engineer. Jim Martin on the tracker team full time.  NASA also helping to add additional support to Italian efforts.

-        Spacecraft development effort on the order of the instrument.

-        Dick as both DPM and Deputy for systems.

-        Must resolve design issues and must understand each production step. Need to shift thinking toward production of flight units.

-        All subsystems about at the same stage – initial start of flight production.

-        Critical path shows CAL ASICs in the lead.

-        GTRC7 at the end of the month.

-        Good progress on ladder production.

-        Design does not usually cause mission failure. More likely to be a small flaw in the manufacturing process that causes any problems. Need the paperwork.

-        Have to balance schedule and cost to get to launch.

-        Focus on tower A. What has to occur to get tower A done? Who do we need? Etc. Need a plan to work through problems in production.


Robert Johnson –

-        Do have baseline for the grid/tracker interface.

-        Looking at modifications indicated by comments from INFN.

-        Corner flexures can be machined completely at the parts level eliminating the bottom tray-machining step.

-        120 degree screws look good. No shims.

-        MCM issues are critical.

-        Sidewalls – finish variation of coupons.

-        Need to verify interface with SSD and MCM.

-        GTRC7 in this month. Should know at the die level within a couple of days and a week at the MCM level.

-        Omnetics connector issues being worked.

-        Resolve EM Testing

-        Manufacturing manpower being added at SLAC.

-        Lots of reviews, particularly production readiness reviews and test readiness reviews. Still need a TRR for the EM TV.

-        Schedule – Emphasized how serious this problem is. We could get cancelled if there is another significant launch slip. Believe we have done all the clever things we can to reduce downstream schedule.

§       Already in trouble with having to show additional schedule slippage at March DOE review.

§       MCMs need to be at Pisa by the third week of March (about 21st). Thus we need flight pitch adapters by the second week of February. Have already produced 800 pitch adapters. Note that pre-production MCMs have GTRC6 ASICs so are not good for flight.

§       Tray fabrication is late getting started. Have sent enough bias circuits to Pisa but need to resolve QA issues with these and at Plyform.

§       Bottom tray may be even more difficult due to Ti parts – Need to resolve I/F problems and revise drawings by the end of the meetings. Getting the parts prepared for the bottom tray is the Tall Pole today.

-        Pitch adapters sent to G&A were not flat. Any like these will be rejected. The 12 that were just measured are “flat”. Creased ones have been rejected.

-        Flex cables are still a concern. Need to get signed IDD.

-        Tom Borden reports COI machined bottom tray closeouts in the 1st week of February.

-        Need to get shipping containers ordered. Must include lessons learned.

-        EGSE – Gunther confident will get two new systems this month.

-        Complete new set of AL honeycomb cores on order. Hopefully have enough for tower A.

-        Need to improve lifting fixture.


Dave Rich – MCM status.

-        Showed process chart. Hand delivered the first 3 units to INFN today. These are trailblazers. Should be bondable. Should be representative in terms of pitch adapter alignment, etc. Fourth unit not sent as part rejected due to poor trimming.

-        Next group of 10 in burn-in and final test at UCSC. Burn-in for flight will be moved to SLAC. Should be ready to ship on Friday 16 01.

-        Teledyne stopped production of later part of pre-production units due to contracts problems. These have been addressed.

-        Pisa wants 6 trays of MCMs. This requires 16 MCMs. We want 20 fro qualification testing. 2 will be destroyed. That leaves 30 for Pisa.

-        Gunther has 36 boards not from this pre-production run – that can have the GTRCs updated to GTRC7.

-        Flight production readiness review on 1/30.

-        Flight SOW ready with Teledyne.

-        In the process of negotiating the flight purchase order.

-        A series of activities are required before 30 01. Major problem is to resolve the pitch adapter requirements with INFN.

-        Shooting for about 100 MCMs a month out of Teledyne. This assumes in-process inspection so we expect very few rejections at the end.

-        Alessandro discovered that the current pitch adapters “are not usable”. Dispersion of the first 12 pitch adapters. We don’t agree with this statement yet but need to get to some resolution before we go to G&A.


Alessandro Brez –

-        Italian efforts concentrated on detectors. Have inspected 8524/9452 detectors. Rejected rate about 1%. Last 2000 detectors are subject to finalization of the order. Should get the last set by the end of January from Hamamatsu.

-        Have 650 flight ladders made. 99 from MIPOT. Rejection rate about 2.2% (15 units).


Francesco Belli – INFN Roma – tray bakeout

-        Ready in Roma for bake out procedure for trays before shipment to G&A.

-        Showed pictures of fixtures and equipment for tray bakeout.


Luca Latronico – Status of database.

-        Currently using database for SSD and ladder testing. Tray testing in work and tower test under development.

-        Next thing is tray production.

-        Flow control may be put inside the database to allow the user to follow a pre-defined procedure.

-        NCR system must be extended for higher level (than ladder) levels of assembly where inputs from the US are required.


Riccardo Bagagli – INFN Pisa

-        Visual and ESPI inspection of the tower.

-        Tested two sides and got the same modal response with frequencies at 130 and 176Hz.

-        Visual inspection with all sidewalls removed. Have done all the visual inspection of the bottom tray. Will take the bottom tray and try to look at flexure bonding, via X-ray.

-        INFN has not agreed to do the thermal vacuum test and then the vibration so their position is once you go to the TV test your vibration testing days are over.

-        Found some damage to the thermal strap. Looks like the source of the limited number of metal chips found. Riccardo believes these chips were done during the torquing of the strap, not due to vibration.


Alessandro Brez – Italian production “boxes”

-        Still needs static test fixture from Hytec and some lessons on what to do. Roccardo has already traveled to Hytec.

-        Very important to test at the stacked tray level before the tower assembly and test.

-        May need to ship the tower from Pisa, rather than Alenia, due to customs reasons.


Luisella Gianni - Plyform

-        Has two main sites. The one in Milan concentrates on auto parts.

-        Have procedures that include tracability of each part produced.

-        Main business is aerospace.


Georgia Pontelli - G&A President – general presentation on company.


Dick Horn with Darren Marsh’s slides on QA.

-        Have to agree on what goes in the travelers that accompany the hardware. This does not have to be the entire end-item data package but must include critical data.


Niccola Mazziotta – INFN Bari

-        Going to do vibration test of the trays after Plyform is finished to ensure we don’t put Si into a bad tray. The tray is then sent to Roma for cleaning and bakeout and then on to G&A for ladders.

-        All trays will be vibration tested, without the SSDs, and Thermal cycled after SSDs are added. Before and after TC trays will be tested in stacked configuration.

-        CPT and LPT procedures will be refined based on mini-tower testing. LPT and CPT may well be defined by the time available to take data. The longer time periods allow for stability testing.


Long discussion on tracker interface -

-        INFN is basically OK with the current concept with the conical seat. They cannot accept any design changes in the bottom tray and the associated assembly procedure.

-        Agreed that we would make all 12 attachments the same and use an alignment jig. INFN will build this jig.

-        They are ready to design a new jig to assemble the bottom tray with the revised bracket assembly.

-        Need to go forward with building the Titanium parts.

-        A mockup at some level is recommended but I believe need to make sure this doesn’t slow down the effort to build the flight, (and demo), Ti parts.

-        First guess from Martin is two weeks to get drawings finished and then 6 weeks to get the parts.





January 15, 2004


Tom Venator

Notes from Pisa Tracker Summit – Version 2


Discussion of MCM results

Looked at pitch adapter results from the previous version. Two units were delivered and measured. The basic problem is that dimensional errors in the pitch adapters may affect bond quality and bond speed. Due to the large number of bonds (8 E5) bond speed is a very important parameter in determining the actual build rate of the towers. We are expecting some comments, and perhaps some “negotiation” at G&A tomorrow. There are two main errors under consideration.

  1. Pitch variation. There is some statistical variation in the spacing of the bond pads. This has been a major concern in driving bond speed. Today the major way of tackling this is to measure the current set of 800 pitch adapters and select those the result in less variability over a ladder, (1/4 of a MCM), and keep this under 30 microns. There is also some shrinkage in the pitch adapters, which Parlex attributes to the etching process. If there is too much shrinkage there is a possibility of ladder bond wires interfering with the bias circuit high voltage pads.
    1. We are going to ask Parlex why, and if, they do not correct for this as it seems predictable.
    2. We also need to check our specification to understand why the MCMs are acceptable.
    3. We also discussed modification of the tooling at G&A to allow for centering the MCM relative to the ladders.
    4. We are going to check with Teledyne to see if they can center the pitch adapters on the MCMs.
  2. Bond pad slope. Discussions with the bond machine people lead to a “less than 4 degrees is easy” statement. Unfortunately the data from the 2 units measured showed pad angles over 4 degrees. This is not a reasonable thing to measure on the entire set of MCM so screening is out and we have to work on a process improvement at either G&A or Teledyne.
    1. A test, with G&A bonding to the 2 units measured has been suggested to evaluate the bond strength as a function of slope.
    2. We are hoping that measurements of the 3 MCMs hand carried this week will show a better result. I believe no additional process improvement studies for Teledyne have been proposed.


Discussion of Darren Marsh email on tray production paperwork.

Reviewed Darrens email and enforced the need to complete this by the end of the month to facility start of the mid-trays. A parallel activity is to select the usable honeycomb from the current lot and have enough assurance to start production at Plyform. Plyform can not start and stop production. Plan is to have Darren review Plyform travelers and procedures on January 27. Also plan to have Ben Rodini there to look at overall practices as well as procedures.


Also discussed with Sandro the need for QA at Pisa. Both G&A and Plyform have existing QA systems but Pisa currently does not. They do have a database for measurements that support scientific characterization but nothing fancy for travelers and NCRs. May have to use a paper system for the first tracker or two. INFN is adding people to address the problem now.


EM Testing

Agreed that we will push on with EM TV. Target date for pump-down is 23 02 04. INFN Bari team is already working toward this date. Plan is to have Tom McCarthy and Jack Goodman out before the end of the month to ensure all preparations are underway. Alenia set-up effort would start 18 02 04 in this case. Note that there are some procurement as well as preparation problems that could cause delays.


Near term goals:

  1. Ready to procure Titanium parts for bottom trays by the end of next week (23 01 04).
  2. Ready to begin mid-tray production by the end of January (30 01 04).

January 16, 2004


Tom Venator

Notes from G&A


I received 5 samples from the Plyform for us to check the plies. Dick would like us to measure thermal conductivity if possible. Should get this done next week before the trip to Milan.


Went over the same presentation of the pitch adapter assembly effort at G&A. They used a clamping system to control the outside edge geometry of the pitch adapter. Results, using rejected PWBs, were very good. This is likely a superior way to attach the pitch adapters, but it has not been incorporated into the Teledyne process. We saw this during the vibration test. Estimates 2 months to implement this into the process flow. This was done at the request of SLAC. As soon as we pay them for it they are willing to send the clamp and samples to SLAC. We are still interested in either incorporating this into the current process at Teledyne but today are not sure how, and more importantly when, this can be done.


Message to G&A. Must build first tower in July and must use the Teledyne product. Saw the result from the last 2 boards and are getting information from the next 3. First one is the pitch. Pitch is typically too short. Can select boards from the pitch adapter with deviation less than 30 micron per ladder. G&A would have to re-align for each ladder. Should have enough for first production. G&A reports that tolerance is importance only for cost. Advertised 30 micron error per ladder in pitch and asked for adjustment possibility of +/- 300 microns laterally.


The primary manufacturing problem with the current design is not the pitch variation but the slopes of the bond pads. G&A notes that variations can, in general, be accommodated, but it increases the time, and thus the cost, of the operation. G&A is concerned about making a production commitment today and wants some time to study the process. They asked for 5 boards but we can easily provide 10 for better statistics. G&A has already measured the 3 we brought along and they meet our pitch variation criteria and thus they already have the first three. We have agree to provide the remaining 7 in two weeks but this is contingent upon the next set of 10 meeting our pitch variation criteria. (Note that the measurement data of the slope of the bond pads was also better than the last set of 2 but there was a pad about 5 degrees). INFN/Pisa is also going to provide a set of AL tray simulators that will assist G&A in studying the bonding by the end of January. Goal is to be ready for tower A 45 days, (5 days/week), to get ready for tower A production. We think this fits the schedule developed on Wednesday.


Also discussed non-destructive testing of the bond strength on the flight boards by using the bias circuit grounding connections. There are 8 of these to the same ground plane on the flight boards. This would likely be a problem for Nick Virmani.