DFM – Design for Manfacture

In the modern world of electronics design and manufacture, where the complexity of the design has to meet with the real world of manufacturing, the need for good design for manufacture (DFM) advice and feedback has never been more important. So why in so many cases has this vital link in the chain become so broken?

I have been around the UK electronics industry for nearly 30 year now, over 20 of which I spent running production in a bare PCB manufacturer. I feel this experience gives me a good insight to comment on the subject of what goes in to making a good design for manufacture. On top of that, I now have the privilege of working for an EMS company that prides itself on its record of giving good DFM advice, which is run by one of the most knowledgeable PCB designers in the UK electronics industry.

What I have seen in recent years, is that designers all too often seem unwilling to ask their supplier’s opinions on a new design, until it is either too late or problematic to change. Then in turn, many suppliers seem to have given up offering good feedback on the issues they encounter when it comes time to manufacture the design.  Both of these often lead to less than optimal conditions for easy manufacture and more complex designs than were possibly required, which in turn leads to higher production costs than were necessary had only a bit of good DFM advice been sort early in the design cycle.

The most usual excuse given for the lack of advice being sort or given all too often seems to be ‘lack of time’! The designer will say the project just needed to get done, they had a deadline and just didn’t have time to go off consult with manufactures. Then in turn the manufactures will say they did not have the time to give feedback, as they were all too busy making the over complex design, while trying to work out how they were going to break the news that the price would need to go up due to the complexity. Though at this stage a good manufacturer should not be thinking just how much extra they can charge due to the products lack of DFM (which many an unscrupulous ones will). What they should be doing is going back to the customer with good feedback on the issues found, along with suggestions on how to solve them with possible tweaks to the design, so they can be fixed before the next round of manufacturing takes place.

However while the lack of good feedback from the manufactures is a big issue, it is not as big as that of the designers not seeking DFM advice early in the design cycle, as this is where early implementation can have the biggest impact on the final products manufacturability and hence cost price. Though in fairness it is not always the designer’s fault this is not implemented these days, as all too often the designer and the manufacture never meet, talk or have any form of contact, as there are so many people in between them. With so many companies cutting their internal electronics design staff to the bare minimum or completely, and then going down the route of using an external design service (nothing wrong with that, before I get bombarded with comments). The designers hardly ever get involved with manufacture of the product they design, that is left to the buyers and intermediaries such as PCB brokers (just an example) to sort out, all of which puts more distance between the designer and the people who ultimately have to make his design.

In the not so distant past, it was often part of the designer’s job to help identify the best manufacturer to suit their requirements and then work with them to get the product in to manufacturer, which allowed an easy path for the DFM feedback loop to take place. However, in the modern cost driven model of purchasing where the product is designed often in isolation and then past to the buyer, who in turn just gives it to the lowest bidder, DFM is all too often left by the wayside, which is rather ironic as if done it would most likely have lowered the manufacturing cost further.

I could go on all day listing all the different cause from the way I see it, as to why good design for manufacture is not properly being implemented, but the simple truth is it’s just all too often a concept that is bantered around but not truly implemented. However, I will throw one more item in for you too considered, often worse than getting no DFM advice, is receiving poor advice. This is usually because the people giving the advice possess little or no real knowledge of the process used that they are advising on. In the past have personally known people who have firmly believed that bare PCB’s were just dropped out of a photocopier like machine, because they had never gone to the bother of actual finding out how they were really made, but who were still then advising people on board design within their company.

Good design for manufacture only ever occurs when the advice is sort from people who actually know and understand in the real world how the manufacturing process works.

Author: Robert Burbidge