I have been wondering, this since i dont have that much experience in product design, but, who is supposed to do the case design of an electronic product? the industrial engineer or the electronic engineer? i have been trying to find the answer to this question last job i had my boss didnt want to allow me (electronic eng) to participate in the case design (i needed to ground it at least)
Enclosing/Casing Design for electronics (electronic eng. vs industrial designer)
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In my industrial experience, the way things generally go in terms of a design cycle follow this sort of flow (condensed version):
- Market research/contact with a customer (identification of the what the basics of the product should be)
- Establishment of a specification (or "spec" as it's often abbreviated)
- A formal quotation and business agreement between the parties (or between engineering and marketing for a 'standard' product)
- Initial design / calculation / simulation / debugging
- Design validation testing, or DVT (you making sure the product meets the spec)
- Bugfix implementation / regression test
- Independent DVT (someone else making sure the product meets the spec)
- Safety and regulatory approvals
- Design for manufacturability review (DFM)
- Production release / marketing release
If you have a project that you've developed, and you feel you're ready to market it, you may want to consider some or all of the following points:
- Write a spec if one doesn't exist. Characterize the typical performance of the product and put this in the spec, as well as any absolute maximums or minimums in terms of 'externals' (volts / amps / degrees) that should be avoided.
- Make sure that your product meets your spec. Do a formal DVT and make a report of the results. Also, test a quantity of boards against the spec and use statistical analysis (Cp/Cpk) to prove that over tolerances and normal variation, you product can do what you say it can do.
- Come up with a reduced number of tests to perform per-unit as a manufacturing reliability test. Bad builds, bad parts, new operators, bad equipment can all lead to problems.
- Make sure that your PCB has in-circuit test pads on as many nets as possible to facilitate in-circuit test (ICT) or manufacturing defect analysis (MDA) - finding problems earlier rather than later is always beneficial.
- If this product is intended to be high reliability, you may want to perform a life test. Run a quantity of units perpetually until something fails. There are industry standards on life testing (acceleration factors, lot size, etc.) which fall beyond the scope of casual advice.
- Consider HALT (highly-accelerated reliability testing) as well - testing the product under thermal and mechanical vibration stress can show weaknesses in the design as well as its construction.
Many of these sorts of tests are big bucks. (Tens of thousands of dollars per test). The cheapest things you can do are those that you can do yourself - the spec, the DVT test and statistical analysis, test pads on the PCB, for instance.
You may wish to consult with an experienced manufacturing engineer to figure out what you really need to do, given your budget and the expected revenue of the product.
Good luck!
Ask Olin :-) - but wear a flame suit.
Unlike data sheets, which SHOULD be holy writ (but often don't quite make it), Application Notes are a very "mixed bag". It does not pay to just take what is in an AN as gospel, although you'd hope it was at least usable without magic smoke.
The following is opinion (of course).
people are most welcome to offer counterpoints to any assessment I make.
Code: When it comes to sample code that comes with AN's, you can expect that it is liable to be "somewhat rushed" if it was written speifically for the AN, and of perhaps grater quality if it builds on existing applications and libraries. Olin, who is far more qualified to speak on this than I am, will tell you that MOST AN code is poor or dangerous. It happens that Olin's company are top Microchip representatives and that Olin is the sort of perfectionist that you'd want as your developer and not want as your boss ;-). ie you can probably be slightly lss scathing about AN code that Olin is, but listen carefilly to his advice.
Hardware: With reference to hardware, you'd hope that an AN writer was highly competent. If the AN is regarding a reference design that they suggest you can use as the basis for a commercial product then you'd also hope they had put their top people on it. BUT if you make a lot of ICs and you want to suggest ways that people can use YOUR product then you can expect "the boy" to write at least some of them. SO be discerning - look at what is suggested and be prepared to find some bloopers.
Chip bloat: A factor which I recalled again tonight when looking at a TI app note is that there is a tendency to "gild the lily' - to use many ICs where fewer may do. Anyone would think they had some sort of interest in getting the IC's into circulation, or something.
Writer reputation counts for much - this is one place where "appeal to authority" has some merit. If Jim Williams wrote it then trust it. Jim died recently and all too many of the other classically trustable names have gone the same way.
Company reputation counts somewhat.
LT are usually good. Mainly with Jim to blame.
AD / Analog devices are usually very good.
NatSemi are a bit of a mixed bag with much good but nothing certain.
Microchip make great products but do rather tend to churn out the app notes.
Burr Brown tend to be keepers of the Holy Grail [tm} but having been acquired by TI the name could get used differently.
TI are usually quite good over many decades. They have acquired NatSemi and BurrBrown and others in recent years and will hopefully bring th average up and not down.
Zetex (acquired by Diodes Inc) make great great great parts (great!) but have been known to write less than perfect app notes.
Nichia tend not to write app notes but if they did you could probably frame them.
Luxeon/Lumileds / Ghost of Philips past write superb technical notes for LEDs. LLP understand LEDs unlike almost any others on the market and can be used to grow your knowledge base when looking at other products.
Atmel/AVR: Should stick to digital which they know very well. Actually usually very good - using body diodes as zero crossing detectors was a fit of momentary madness.
Hewlett Packard: Old School HP technical stuff was utterly utterly utterly superb. Utterly. Novo Riche HP if they produce app notes of relevance should be treated with care. Pass by on other side if in doubt. Agilent carries much of the mantle of the old HP and can largely be trusted.
Motorola of old not too bad at all. On Semi followed fairly well. Spun off children maybe also.
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Best Answer
Since the aesthetics of the enclosure are often what distinguish your product in the marketplace, it is an industrial designer, not an industrial engineer, who should be doing the enclosure design. Your company may have one in-house, or hire one as a consultant.
The industrial designer will be working with any other engineers involved in the project, such as electrical, mechanical, and industrial, plus a human factors person, and will be responsible for seeing that the enclosure meets all the electrical, mechanical, and regulatory requirements of the product.
I don't see that an electrical engineer would be too involved in the initial case design, except to give to the industrial designer a BOM of all the large parts anticipated to be used in the design. Often, a case design will be influenced by whatever type of display is being used and other user interface features (buttons, etc.). There may be some back and forth between the EE and the industrial designer on some of these components.
After a case design has been proposed, then the EE would need to make sure there is enough room for whatever PCB's are needed and also cutouts for connectors, that there is adequate height for tall components, and any thermal considerations are taken care of.
The industrial designer will typically render models of the enclosure using a 3D CAD program like SolidWorks. Programs like this can usually exchange files with PCB layout programs like Altium Designer, for example, to make sure mechanical features of a PCB like a cutout for a mounting post like up exactly.
3D modelling programs can be used to design enclosures that will be produced either in metal or plastic. Prototypes are usually made using 3D printing. Later, instructions for making a mold or CNC instructions for making a metal enclosure can be output from the CAD program.
When designing the enclosure, it is important for the industrial designer to keep manufacturing costs in mind; adding additional complexity to a mold can easily cost an extra $10,000.