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The mandate of the DEM group is to provide CERN-wide support for
the layout, production and assembly of printed circuit boards, flexible circuits, hybrids and fine pitch detectors. |
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Group
Leader: E. van der Bij |
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Electronics Design Office |
Photolithography & Microconnectics Technologies |
Assembly Workshop |
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The three sections of the DEM Group function with a light structure of CERN staff where the major part of the work is performed by teams working under a single industrial service contract. The production of fine-pitch detectors in the cleanroom of the PMT section is operated exclusively by staff to protect and develop this core-value of CERN. |
The group provides CERN-wide support in the following fields of production of electronics:
As CERN engineer or engineer from a collaboration you enter the service in the DEM-BE section (B. Magnin, electronics-design-office@cern.ch) with schematic diagrams that you made in Cadence or PCAD. If necessary, you can even come with hand-drawn schematics. The design office can also design mechanics such as front-panels and small crates.
Based on when you need the prototype, a planning is made. Also dates will be fixed on which you have to verify the placement and the PCB layout. The fabrication of the boards is not started until you have given your OK. You should provide us the components that are not existing in the CERN stores; there is no need to give standard resistors and capacitors (SMD or Pin-Through-Hole). Please tell us if you like us to buy all components for your project.
The design office stores all schematics, manufacturing files and documentation in the EDMS system so you can reach them over the web. Also placeholders are made to which you can attach other documentation such as user guides, specifications and photos (example, other EDA examples).
The DEM-BE section takes care of the handling and ordering (including the small mechanical parts and front-panels) and will give you the completely assembled cards or crates on the date that was agreed on. If we foresee a delay in the delivery, we will inform you immediately.
Prototype quantities of boards (up to 10) are normally completely handled
within CERN. For somewhat larger quantities and in special cases, the DEM-BE
section will organise that the production of PCBs and the assembly will be done
by commercial companies. For this CERN has negotiated contracts with several
companies. Those contracts are based on a large volume and have followed the
official CERN/FI
tendering procedures.
Users are encouraged to contact the design office
so that those cheaper PCB contracts can be used.
For large scale production, where the total cost will be more than say 40 KCHF, the DEM group will not be able to do the full work for you. In this case you might have to go through the official Finance procedures such as Market Survey and Call for Tender. Be aware, the total process for this may take up to one year and will have to be done for a large part by yourself. Have a look at the CERN Purchasing Service Home Page for more details about the rules.
If you have designed your own PCB, flexible circuit, hybrid or detector, the DEM-PMT section (R. de Oliveira, electronics-pcb-workshop@cern.ch) can produce it in prototype quantities. To make sure that the files are correct and are compliant to the technical norms (e.g. Class 6), you should pass via the design office in the DEM-BE section for a final check. Also in this case you will receive a complete planning for the production and assembly of your board. If you need a somewhat larger production, the DEM-BE section can help you, backed by technical support from DEM-PMT for complex products.
If you just need components to be mounted on a board, you should first see the DEM-BE section (B. Magnin, electronics-assembly-workshop@cern.ch) where the work will be verified before it is given to the assembly workshop. In most cases specific manufacturing files for the solder dispenser or colour plots of the location of the different components are needed. The DEM-BE section can generate those files for you. Cables can normally be made based on simple documentation.
For rework on PCBs, such as replacing connectors or components (including BGAs) you can go directly to the workshop located in building 1/1-015 or call them before on 72694. In most cases you can have your board back within half an hour!
If you have any questions, don't hesitate to contact us.
A commonly asked question is: "How long will it take you to build my design?". Our answer is: "Count ten weeks in total". Those ten weeks include all phases of the production of your board, from the PCB layout until the final assembly of the components. We will organise all those steps for you, just come with verified Cadence or PCAD schematics that use the CERN central symbol libraries. Some five weeks later you should give us the components that are not available in the stores.
The table below shows how this production time is built up. Notice that instead of having a margin for each of the phases, we have all margins collapsed at the end. So it might be that you get your fully assembled board even earlier!
| Prototype electronics production - multi-layer PCB, standard priority | |||
| Layout 4 weeks |
PCB
fabrication 3 weeks |
Assembly 2 weeks |
Margin 1 week |
What do we do when there is an overload? We outsource. For all phases we have contracts with companies outside CERN that can do the job. Delivery times should stay the same.
What can you do to help us keeping our delays? Please tell us a few weeks in advance on which date you will come with your schematics! That's all we ask.
With an early planned entry date, we can schedule your job early enough, so we don't have to disappoint anyone or that we have to urgently shuffle jobs and delay the schedule of one or several of your collegues. The entry date also gives a nice deadline for you as engineer, which reduces the risk that your project slips. An early announcement sometimes can make that the four weeks of the Layout phase can be reduced to only two.
Please contact us if you have any special needs, be it in technical details or in planning.
Services from TS-DEM (.pdf, 3.5 MB)
Presented to the AB/BI group, July 2007
The role of DEM at CERN. Presentation (.ppt), Paper (.pdf)
Presented at the TS Workshop, May 2005