Packaging of a miniature Piezo electric sensor
Functional packaging for a technology demonstrator EV-Board. The side perforation is for placing light sources and detectors
Packaging and housing solutions
CSTM specializes in opto-mechanical housing solutions, in realizing custom electronic enclosures, and in component encapsulation. Solving enclosure and housing problems is a common practice in many of CSTMs projects and is addressed with a methodology that aims to eliminate any negative effect of the housing or the housing process on product performance.
• Optical packaging – centralization, stress release, thermal expansion compensation, placement accuracy, placement repeatability.
• Electronic packaging – complying with various standards for electronic and electrical packaging, heat removal techniques, rail guidance, EMI\RFI protection, PCB solutions (slotted motherboard, subracks, subassemblies, FPC, rigid-flex), multi-purpose parts for cost reduction, manufacturability, maintainability.
• Component packaging – COB techniques, placement accuracy issues, enclosure durability issues, QA issues, custom placement equipment (active alignment and bonding devices)
Packaging development process
A packaging development process is similar in nature to a layout process – it is iterative. Each requirement is like a piece of a puzzle that needs to fall into place. CSTM aims to work in a structured manner defined in the flow chart on the left, which has proved to have this process reach a successful ending.
Define the housing’s TOP LEVEL specification, Relate to the following points:
• Compliance with standards
• The finished product characteristics (compatibility, materials, design, Finish)
• EMI / RFI
• Environmental conditions (temp \ humidity, wetting, shocks\vibrations, pressure, corrosion, radiation)
• Enclosure’s interface with the outside world (Electrical, Electronic, RF, Induction, Optical, Mechanical)
• Optical requirements (Windows, injections, coatings, etc.)
• Heat removal requirements
Suggest a concept for an enclosure that is compliant with the spec. The concept is to be amended in an iterative manner until approved or rejected and replaced by an alternative concept
The concept should relate to three aspects:
• Desired packaging method
• Manufacture process and derived assembly issues
• The hardware to be enclosed – PCBs, components and assemblies (It is recommended to initiate the housing project prior to finalizing the BOM and manufacturing the PCB. The project should be entered with sufficient freedom to select critical components such as the panel components or heat generating components)
3. Preliminary engineering design (ends in a PDR)
3.1 Preliminary content modeling
An interaction between the system engineer and the packaging engineer results in a system model of the enclosed part.
The design should relate to the following points:
• Dimensional setting of the enclosure and its contents – based on preliminary insights
• Component engineering – Finding the most appropriate alternatives to components and assemblies
• Location of critical assemblies and components (Panel Components, hot and protruding components)
• Definition of the mounting areas (for the circuits or elements to be enclosed)
• Heat removal analysis (no simulation required – preliminary stage) may cause component repositioning
• Relate to the environmental conditions inside the enclosure ( suppression of vibrations for instance)
• Produce a DXF or IDF file for a circuit layout design.
3.2 Circuit layout stage (if needed)
Preferably, layout design should be carried in IDF (3 Dimensional) as an iterative interaction between the packing engineer and the layout designer. The layout designer will be asked to try converging to the specified dimensions. At this stage it is important that the layout designer has the correct libraries of all relevant components.
There are several acceptable options for working with IDF files:
emn\emp or brd\lib or brd\pro or bdf\ldf or idb\idl.
IDF files consist of pairs of files, one describing the circuit, and the other contains the component library.
3.3 Preliminary Enclosure design
A full preliminary design solution is given. which relates to:
• All components (Enclosure, functional assemblies, mounting items)
• All relevant system configurations (often there are many combinations)
• Environmental conditions
• Heat removal (run a simulation at this stage)
• Tolerances analysis
4. Critical design (ends in a CDR session)
• Complete and correct the preliminary design
• Manufacture a Mockup if necessary (helps lowering risks)
• Tolerance budgeting
• A “Test Procedure” paragraph as part of the “Engineering Spec”
• Relate to the process of manufacturing, test, assembly and calibration.
• Examine the need for dedicated equipment to support the assembly process
Complete model realization plus a repair round
CSTM has gained extensive experience in a variety of packaging projects: housing of laser projectors of different kinds, large scale packaging (multi assembly) of fiber communication systems, packaging of single and double injected optics, packaging of miniature electro – optical elements, simple metal enclosures …
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