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31 October 2008. After his recent visit to CERN, Joe Fjelstad,
inventor and authority on flex circuits, made the interesting audio column "Research
and Innovation Thrive at CERN" (transcript). Quote: "Innovation in the realm of electronic
interconnects is alive and well in Europe. The online magazine for the PCB industry PCB007 also reported about Joe's visit in "Fjelstad Visits CERN Accelerator Complex". |
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 28 October 2008. After careful evaluation the assembly workshop has
decided to use just two types of solder: one lead-free
(Sn95.5Ag3.8Cu0.7) and one containing lead (Sn62Pb36Ag2).
To
make these types of solder easily available, the CERN Stores keeps these
in stock.
As the lead-free solder has a much higher melting temperature than leaded solder (217 °C vs. 179 °C), the risk of damaging the components and PCB is increased. The temperature control of the soldering iron has therefore become much more important than before and is the reason why we also have standardised precise soldering irons with dedicated tips for touch-up and repair work. If you like to get more information of the standardised solders, flux, desoldering wick and soldering irons or like to try them out please contact Sylvain Kaufmann. |
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October 2008. Joe Fjelstad, a veteran of the electronics
interconnection industry and international authority, author, lecturer
and innovator with over a hundred US patents in the field, visited CERN.
The exchange of ideas about production techniques may help us both to advance into the future. Joe also gave a lecture in which he presented many practical things such as how the layout of flex circuits can make them more reliable. Furthermore he presented his visions on embedded logic and splitting high-speed chip-to-chip communications from the other connections. The latter ideas are still rather far off from being reality, but they may indeed show future directions and hearing them was rather stimulating. If you're interested in his ideas, the free book Flexible Circuit Technology is a good starting point. |
TOTEM
Roman Pot detector, a marvel of technology|
16-layer board connects all 10 detector layers |
12 September 2008. The special CERN Bulletin (No. 37-38/2008) with
articles about the First Beam events describes shortly the
different detectors of LHC. About the "Roman Pots" of the TOTEM
experiment it writes: Veritable marvels of technology, these cylindrical vessels can be moved to within one millimetre of the beam centre. They contain detectors that will measure very forward protons, only a few microradians away from the beams, that arise from elastic scattering and diffractive processes. On the accompanying image you can see the stack of ten different flex-rigid circuit boards with an integrated special layer of material that removes the heat from the silicon detectors. The density of lines, the planarity and the overall dimensions are important features of it. The Motherboard that connects all these detector boards has 16 layers (pdf 3MB). The layout and production of the boards and the assembly of the components have all been done by TS-DEM's services. |
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September 2008. Over a year ago two physicists started a spin-off company in Heidelberg based
on work performed for a neutron physics detector project at the
Physikalische Institut of the university of Heidelberg. This company
called "CDT CASCADE Detector Technologies GmbH" makes GEM-based neutron detectors
developed with the CASCADE detector project. One detector of this type
may contain up to ten GEM foils resulting in an extremely high
sensitivity. The speciality of CDT is to make fully working
turn-key systems that include the readout electronics and software. The
company adds precise Boron
conversion layers to GEM foils to convert the 'invisible' neutrons
to photons that can be detected with the mature GEM technology. CDT has
received serious interest
from Japanese companies and European institutes.As CDT now is ready to sell its detectors, it requested CERN a licence to use the patented technology in a commercial application. CERN has awarded this request. Commercial details have not been disclosed. For more information and technical details see the website of CASCADE Detector Technologies. |
Gas detectors advance into a second century|
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27 August 2008. The CERN Courier of September 2008 features the article "Gas
detectors advance into a second century". It describes the
workshop at Nikhef that was organised to work towards the foundation of
the RD51 collaboration. RD51's aim is to get institutes together to
jointly research and further develop micropattern gas detectors
(MPGDs) such as GEMs and MicroMegas.
There are numerous applications of MPGDs. In R&D studies, thick GEMs are used for the detection of single photons in Cherenkov imaging counters. At Jefferson Lab, a new multipurpose spectrometer is being developed, where GEMs could be used in particle tracking at high rates. GEMs are also being developed for digital hadron calorimetry in experiments proposed for the International Linear Collider (ILC) – a very high granularity can be achieved with small cells that are either "on" or "off". Groups working on experiments for the ILC have in addition designed large TPCs with MPGD read-out, and both GEMs and MicroMegas are being considered for this role. In other developments, MicroMegas detectors read out the TPC for the Tokai-to-Kamioka experiment in Japan, or can be used as muon detectors at high counting rates, such as in the upgrade of the ATLAS detector at CERN for the SLHC. As maker of high-quality GEMs and MicroMegas TS-DEM is convener of the RD51 working group on "Development of cost-effective technologies and industrialisation". This working group aims to develop a common production facility, to optimise production industrialization (quality control, cost-effective production, large-volume production) and to guide collaborations with industrial partners. You may contact Erik van der Bij if you are interested in this working group. |
Expertise of TS-DEM
helps developing low
material budget detector|
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20 August 2008. The CERN Courier, the International Journal of High-Energy Physics of July/Aug 2008, printed monthly in 22 thousand copies, featured the 4-page article "Pixels make for perfect particle tracking in ALICE". Some very nice images in this article show the barrel with the flexible circuit cables made in the DEM workshop. The article specifically mentions the pixel bus, a project that we are very proud of: |
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Material budget considerations also led to the development of the pixel bus, a high-density aluminium/polyimide multi-layer flex. This technology, in which aluminium is used in place of copper, is not an industry standard and was made possible by the expertise available in the TS-DEM workshop at CERN. |
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The material budget of this pixel detector is so important as it is the first detector that the particles cross after collision. You may appreciate the technological complexity of this project by viewing The development of the fabrication process of "low mass" circuits presentation of Rui de Oliveira. The assembly workshop TS-DEM soldered all components on the modules used in the 120 half staves, while the PH Bonding lab has made the die attachments.
The CERN Courier wrote also on a previous occasion about TS-DEM: "Spark-proof GEM gives higher gain". |
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12 August 2008. One of CERN's subcontractors had problems with the soldering of Ball Grid Array components with 668 pins on cards for the COMPASS DAQ system. Fortunately we could recover the 136 cards by doing a reflow through DEM's oven with a well calibrated temperature profile. In addition, because of a design issue, 1600 resistors had to be added afterwards. The best quality solution found was to solder these small components (measuring just 2x1 mm!) manually on top of existing ones. It was good to see that we could quickly recover from these design and production problems and that COMPASS was soon ready for commisioning.
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PCAD library support stops end 2008 |
6 August 2008. Altium, the supplier of PCAD, has
stopped the support for PCAD.
As announced last year (e-mail to CERN's PCAD users from 8.6.2007), PCAD
can therefore no longer be supported at CERN. PCAD users are therefore
strongly advised to migrate to Altium Designer or Cadence for new
designs. Altium Designer can import PCAD designs and it is available for installation from CMF. Special migration courses for PCAD users as well as courses for schematics entry and PCB design with Altium Designer are organized by technical training, there are upcoming sessions in September and October. TS-DEM will support Altium as it did PCAD, i.e. manage the libraries and route printed circuit boards. TS-DEM can also migrate existing PCAD designs to Altium. |
Beware the single hit!|
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July 2008. The CERN Bulletin (No. 28-19/2008) published the
article "Beware
the single hit" about the radiation monitors designed by the
TS-LEA group. In total, 329 radiation monitors have been installed in
the LHC tunnel and its experimental areas.
It is not mentioned that it is TS-DEM who has produced these monitors for the team of Thijs Wijnands and Christian Pignard. In fact since 2005 DEM has been tightly involved in the development of these RADMONs (or EDA-01793 in our terms). We designed and built the various PCBs (main card, power card, sensor cards), the compact metal box around it and various adapters that allow the radiation monitor to be fixed to various structures in LHC. |
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Mai 2008. The TS-DEM group is a member of
IPC (Association Connecting Electronics
Industries) and its European counterpart
EIPC (European Institute of Printed
Circuits) and participates regularly at conferences organised by
these institutions.DEM bases its quality control largely on IPC standards that are recognised world wide. One of the norms is IPC 7711/7721: "Rework, Modification & Repair of Electronic Assemblies" of which a new version is just released. Other important IPC standards we use are IPC-A-600-G: "Acceptability of Printed Boards" and IPC-A-610-D: "Acceptability of Electronic Assemblies". DEM also uses these standards in the technical specifications and when qualifying its PCB producers and assembly companies. Selecting the right IPC norms is not always an easy task as there is a complete IPC specification tree and sometimes they need to be tailored to CERN's specific needs. |
Technology Transfer of GEM technology|
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14 April 2008. The CERN Bulletin (No. 16-17/2008) published an
article about the creation of a European network dedicated to technology
transfer. As TS-DEM together with the TT unit at CERN have made several
technology transfer contracts for the production of Gas Electron
Multiplier detectors, a project dear to TS-DEM for TOTEM was
specifically mentioned: "The gas detectors for the TOTEM experiment (GEM) offer potential for fruitful collaboration within the framework of the TT network. Many other technologies are going down the same road." |
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March 2008. As part of
a new project to develop the controls electronics for the PS
renovation and the future machines such as the Linac4 AB-PO-CC are
developing the third version of the function generator/controller
(FGC3). For the prototyping phase the TS-DEM group will provide the PCB
layout and fabrication service.
TS-DEM showed their assembly facilities to members of the FGC3 design team during which Quentin King, section leader of AB-PO-CC made a nice series of photos that show the assembly process. The complete slideshow shows even more details with comments. |
The master craftsmen of the electronics
world|
Scoop! |
4 February 2008. The CERN Bulletin (No. 06-07/2008) published
a flattering article about the TS-DEM group.
At the forefront of the development of electronic modules, the DEM group provides continuous support for the engineers and technicians of the LHC experiments."Electronics at CERN are in a way CERN’s nervous system. Electronic components form an integral part of the data transfer and detector control systems", says group leader Erik van der Bij. "Our objective is to be able to provide the expertise that is not available in industry." |
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January 2008. To improve the quality of the work in the electronics
assembly workshop we have recently purchased two small but very useful
machines. One is a pneumatic press for precisely inserting press-fit
connectors. As there is a spring mechanism that makes the contact to the
metalised hole in the PCB these connectors don't need any soldering.
They have the additional advantage that they can be replaced up to five
times without even damaging the printed circuit board! For new designs
such as VME boards we therefore strongly recommend press-fit connectors
instead of solderable ones.
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28 January 2008. Claude Millerin, who most of you know as leader of
the SMD and cabling workshop, left CERN. When he arrived in 1970 to work
at CERN he built analog and digital electronics for wire-chambers, drift
chambers and electronics for the UA1 and Aleph experiments. In 1987 he
started the SMD workshop that is now part of TS-DEM.
In 2005 he reinforced DEM's design office section to set up a professional subcontracting service with the additional service of purchasing electronics components. After 38 years of CERN he now retires and will stay active with his car hobby. We very much appreciated all his work and presence and wish him and his family a long and healthy life! |
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January 2008. With the change to lead-free (RoHS) solders the
quality of the temperature profiles and ovens used have become much more
critical. The American SMT Magazine
has recognised this and made the survey "Inside
Reflow" about modern practices. Also CERN has participated in SMT's
survey and comments from TS-DEM have been quoted next to remarks from
specialists from the world's largest assembly companies such as
Flextronics, ATS and TRW."Sylvain Kaufmann, production technician at CERN/European laboratory for particle physics, talks about the need for accuracy — it has increased with the growth of component size and sensitivity variety. Flexibility became a major factor." "Temperature and ΔT during process steps (preheat, soak, peak, etc.) and repeatability from week to week are important to Kaufmann at CERN. He measures these using generic boards pre-wired with thermocouples connected to a thermal profiler." |
A Silicon Tracker for Christmas|
TS-DEM participated in
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22 January 2008. The article "A
silicon tracker for Christmas" in the CERN Bulletin (issue
04-05/2008) describes the final installation of the CMS Silicon Tracker.
Inside this detector there are a total of 10 million detector strips
read by 80,000 microelectronic chips. These strips and detectors are
connected together on so called hybrid circuits.
The article does not tell that Rui de Oliveira, section leader of DEM's PCB workshop, had helped to solve severe production problems of these hybrid circuits. On Rui's suggestion the stack-up of the different layers inside the circuit was modified to prevent via holes to crack and generate bad connections. Furthermore he interacted with the production company which resulted in a document that improved the quality assurance for the production of these hybrids. TS-DEM is happy to have participated in making this project a success. This example confirms the statement of the CMS spokesman Jim Virdee: "Building a scientific instrument of this size and complexity is a huge technical and scientific achievement". |
CERN apprentice receives award|
Every year DEM gives practical training to apprentices |
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January 2008. "CERN
apprentice receives award" reads the heading in the CERN Bulletin
(issue 04-05/2008). It was electronics technician Stéphane Küng who was
honoured in November by the Social Foundation of the Union Industrielle
Genevoise (UIG) as one of Geneva’s eight best apprentices in the field
of mechatronics.
What is not written is that Stéphane has learnt the art of electronics production in the electronics design office and the SMD assembly workshop of TS-DEM. He spent 6 months with us during which he also learnt how to produce printed circuit boards. In fact every year DEM trains up to two apprentices in collaboration with Jean-Marc Bouché, head of CERN’s apprentice training programme. We're very happy that Stéphane has won this price that will most certainly help him in finding an exciting first job! |
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11 January 2008. On 11 January at 8:30 we received a request from
AB/CO to find the fabrication files of an 11 year old design with only a
few references such as "J24415" and "80 418 CO 801d" written on the PCB
and paper schematics. These are the type of reference numbers that we
used before the famous EDA numbering scheme. Just 22 minutes after the
request we had found the files that were in fact in 2003 already
restored in EDMS.
Anyway, we are well prepared for this type of demand: after the "copy
that floppy" action in 2007 we can easily go back electronically to
1988. A series of these so-called GDAC GFAC boards, that control most of the power converters of the PS complex, needs to be fabricated again as the Controls group in the AB department is running low on stock. To be able to survive until a new system is designed TS-DEM will produce 50 spare cards. |
In 2007 more jobs needed |
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A large amount
of work
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... for the LHC Experiments and for new |
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... and we should not forget that the
massive kicks
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