TLA Microsystems - Design for Manufacture(TLA_TOP.GIF-23k)

Design for Manufacture

Design for Manufacture (DFM) is one of those terms that comes up often but with little or no explanation. It is a broader subject than can be covered in a 2 hour seminar or by purchasing another expensive add-on for CAD software. The facilities usually equated with a DFM option are only a small part of what designing for manufacturing is all about.

As the expression implies, there is a distinction between an electrically competent design and one that is suited, or more importantly, optimised for the manufacture of that particular product.  Each product must be treated individually and the design must take into account the expected production volumes (both short and long term), who will be doing the manufacturing (inhouse or external contractors), what type of infrastructure is in place (is the manufacturer currently making electronic products), is the product disposable or serviceable,  and so on. Closer to the product itself are issues such as packaging, housing manufacture, multiple language/facility/upgrade options and intended market perception.

Many of these things (and DFM itself) are not immediately tangible items. They can't be shown as distinct items in a costing or on "the bottom line". Well, often not in the short term, anyway. Items that haven't been designed with production in mind are nearly always still able to be made, but with a degree of reluctance. The only way an external supplier can express this is through increased pricing or perhaps everybody disappears when you arrive at reception. If something is difficult to make, the staff involved become less than enthusiastic about doing it and a lowering of morale drops the overall productivity. Not just for that particular product.

DFM is often considered a subject for high volume manufacturers but this isn't the case. If the product is to be made in a garden shed, there are still many areas that can be considered at the design stage and make life easier. For example, selecting components that have multiple supply sources, short lead times (if not ex-stock), are easilly distinguishable, large enough to be handled and the locations are clearly marked on the PCB. The same product for volume production may use surface mount components and have no component legend, be supplied in a 20 up panel with optical and physical orientation marks and include free areas for the placement machines.

TLA Microsystems works on the principle of "saving favours". If the majority of products are as close to ideal as a supplier would like, when that one comes along that just has no alternative but to be difficult, the door is still open. For example, many PCB manufacturers can make boards to 0.006" design rules. If that is the manufacturing limit of that supplier, whenever they have a problem it will be your boards that are going through at the time (Murphy's Law). Unless you actually NEED that level track density, why do it ? Let someone else enjoy that moment.

Designing for manufacture can only really be attained through experience and establishing a good relationship with suppliers. Ask a supplier if they can do "XYZ" and they'll answer "yes" (unless you are at the wrong address). Once you know them a little better, you'll find that they can do it, but would prefer "XyZ". Having spent many years working with large, small and contract manufacturers, TLA Microsystems can pass on that experience and structure a design solution that best suits your particular product and circumstances.

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