Design for manufacture - question

Thread Starter

Mariusz777

Joined Apr 2, 2021
9
I am quite new to design field and would appreciate some help on high-level plan for the introduction of a simple product design into manufacture (from specification to production). I would also want to ask about paperwork generated throughout. Thank you.
 

dl324

Joined Mar 30, 2015
13,087
Design For Manufacture means different things in different disciplines.

I worked in semiconductor manufacture and DFM for us meant using more conservative design rules, adding redundant vias/ contacts, operating conductors at lower current densities, having spare blocks of memory that can be fused in to replace defective blocks, etc.
 

MrSoftware

Joined Oct 29, 2013
2,015
That's a really vague question and the answer can vary a lot depending on what it is you're manufacturing, what volume you want to make, where your parts are sourced from, who is doing the assembly and where they're located, what your primary goals are (quality over cost, cost over quality, quick turn around, etc..), and surely some other things I'm not thinking off at the moment. If you can tell us more about what you want to make then we can help you more.
 

Thread Starter

Mariusz777

Joined Apr 2, 2021
9
That's a really vague question and the answer can vary a lot depending on what it is you're manufacturing, what volume you want to make, where your parts are sourced from, who is doing the assembly and where they're located, what your primary goals are (quality over cost, cost over quality, quick turn around, etc..), and surely some other things I'm not thinking off at the moment. If you can tell us more about what you want to make then we can help you more.
I am looking at wireless sensors for manufacturing industry as well as home users. We are talking here of battery powered ultra low voltage devices where battery lasts 10 -15 years. I am just trying to find out how to address it. When would be looking for pointers on how to approach the design itself. It would be great if I could find out where in the plan EMC would be addressed as well as CE making.
 

MrSoftware

Joined Oct 29, 2013
2,015
The first thing you need to do is draw up a requirements document. This will have every mandatory feature and desired feature. Start with an outline then fill in the details. Size, communication protocols, range, certifications, battery life, other devices or systems that it must work with, per-unit cost, failure rate, etc.. Include aesthetics if that is also important, everything you can think of. Be sure to include a section for acceptance tests. Acceptance testing is like the final end to development. When you hire someone to make a product for you, both sides are satisfied that the product is complete when it passes the acceptance tests, so include every single thing that is important, in detail. Don't say "it has to have good range". Say "it must communicate at 10Mbps error free at 100-feet line of sight with no obstructions in the North-South direction at noon on a Friday in the parking lot at 123 main street exactly 50 feet form the north sidewalk, while sitting on a wooden table 3 feet off the ground in direct sunlight and ambient temperature between 80F and 90F". You get the idea.

Start with the details that you know, fill in as much as you can, and at some point you will need engineering help to fill in the details. The requirements document can be a significant part of the project, it's going to take some work.

Now you have a document to show to potential design teams and consultants. If you go to a design house and say "how much to make me a wireless device with a 15 year battery life", they're going to politely walk you back out the door. If you can show them your design requirements document and say "how much to make this exactly", then you can have a real discussion. It's OK if you approach the design team not knowing the more technical details, that's part of what you're hiring them for. But you need to have the basic functionality outlined clearly.

One free tidbit; do not go to an engineering firm and say something like "I have this great idea, if you design it I'll give you 10%". Unless your project is a unicorn, you will likely be looked upon as less than serious and under funded and it will be difficult to get the attention of a very good team. Come in knowing exactly what you want and knowing that you're funded and you will get more attention.
 
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Thread Starter

Mariusz777

Joined Apr 2, 2021
9
The first thing you need to do is draw up a requirements document. This will have every mandatory feature and desired feature. Start with an outline then fill in the details. Size, communication protocols, range, certifications, battery life, other devices or systems that it must work with, per-unit cost, failure rate, etc.. Include aesthetics if that is also important, everything you can think of. Be sure to include a section for acceptance tests. Acceptance testing is like the final end to development. When you hire someone to make a product for you, both sides are satisfied that the product is complete when it passes the acceptance tests, so include every single thing that is important, in detail. Don't say "it has to have good range". Say "it must communicate at 10Mbps error free at 100-feet line of sight with no obstructions in the North-South direction at noon on a Friday in the parking lot at 123 main street exactly 50 feet form the north sidewalk, while sitting on a wooden table 3 feet off the ground in direct sunlight and ambient temperature between 80F and 90F". You get the idea.

Start with the details that you know, fill in as much as you can, and at some point you will need engineering help to fill in the details. The requirements document can be a significant part of the project, it's going to take some work.

Now you have a document to show to potential design teams and consultants. If you go to a design house and say "how much to make me a wireless device with a 15 year battery life", they're going to politely walk you back out the door. If you can show them your design requirements document and say "how much to make this exactly", then you can have a real discussion. It's OK if you approach the design team not knowing the more technical details, that's part of what you're hiring them for. But you need to have the basic functionality outlined clearly.

One free tidbit; do not go to an engineering firm and say something like "I have this great idea, if you design it I'll give you 10%". Unless your project is a unicorn, you will likely be looked upon as less than serious and under funded and it will be difficult to get the attention of a very good team. Come in knowing exactly what you want and knowing that you're funded and you will get more attention.
Lets say I have the requirements document ready would the next step be generating ideas on how to approach the requirements lets say different technologies etc. than assessing feasibility of each in regards to price and market
 

MrSoftware

Joined Oct 29, 2013
2,015
You're on the right track. I think what you're looking for is a feasibility report, basically a marketing level document that helps you figure out if there is actually a market for your product, and what price constraints you would need to work within to be profitable. Maybe what you're really looking for now is a feasibility study and the resulting feasibility report?

Once you know your idea is feasible, then you would finish up the requirements document. You may well need engineering help to finish the requirements document, but you should already have a pretty clear idea of what you want the final product to be when you create the requirements document.

Disclaimer: I've produced and brought a few of my own products to market, but there was no feasibility study required (the market was pretty clear to me), and I've worked on the engineering side of a few engineering-for-hire projects, but I'm not the most savvy on the nitty gritty business side stuff. I would not be the best reference for writing a formal proposal to show to investors. What you might want to find is an engineer who also has an MBA. There are probably a few around here, perhaps one will jump in and help out.
 

Thread Starter

Mariusz777

Joined Apr 2, 2021
9
You're on the right track. I think what you're looking for is a feasibility report, basically a marketing level document that helps you figure out if there is actually a market for your product, and what price constraints you would need to work within to be profitable. Maybe what you're really looking for now is a feasibility study and the resulting feasibility report?

Once you know your idea is feasible, then you would finish up the requirements document. You may well need engineering help to finish the requirements document, but you should already have a pretty clear idea of what you want the final product to be when you create the requirements document.

Disclaimer: I've produced and brought a few of my own products to market, but there was no feasibility study required (the market was pretty clear to me), and I've worked on the engineering side of a few engineering-for-hire projects, but I'm not the most savvy on the nitty gritty business side stuff. I would not be the best reference for writing a formal proposal to show to investors. What you might want to find is an engineer who also has an MBA. There are probably a few around here, perhaps one will jump in and help out.
Ok lets assume feasibility has been assessed and the requirement document written. Lets also assume I have got 4-6 different approaches (i.e. ideas of hardware that can be used for the development). I would go through the hardware implementation ideas as pick one which is most suitable (price, availability, complexity whether it can be manufactured for instance can the company populate BGA package or I should stick to QFP). After choosing the idea/hardware to fulfil the requirements can I go directly to prototyping stage? Lets say I have already contacted software engineer who will be writing the code - btw should I get some sort of document informing about software requirements for the product from software team i.e. hardware required on the MCU or this decision is down to myself and implementation. Furthermore at this stage I should start working with the software team directly regardless whether there is a requirements document or not so eventual changes can be rectified smoothly. Now after verification of the prototype should I go to schematic capture and pcb design or there are requirements i.e. documents to be produced after prototyping stage. Moreover lets assume the pcb has been designed including test points for ATE test, when would I produce a document specifying test points - is it a separate document or including it in the test spec is sufficient enough.
 

MrSoftware

Joined Oct 29, 2013
2,015
You're jumping all over the place. Is your goal to figure out if your idea is feasible, or to prove that your idea works from a technical perspective, or do you know your idea will work and you want to hire someone to build it?

Proof of concept builds are absolutely a good idea, and before designing custom hardware. Use as much off-the-shelf development hardware as possible to prove that the idea is technically sound, then worry about custom hardware. What stage are you at? Are you sure your idea is technically sound, or do you still need a proof of concept to prove that it works?

In regards to your question about requirements for software; on the projects I've worked on, all of the specifications are in the same product requirements doc, both software and hardware, and the company that I worked for handled both. We had software guys, firmware guys, hardware guys and mechanical guys, it was a one stop shop. You can certainly split it up and take it to different places if you like, but it may be a lot simpler to have it all done under the same roof, if you can find a company that can do it all.

If you know ahead of time that you are going to need some specific test points then they should be specified in the requirements doc. During development it may become apparent that additional test points would be helpful and they can be added.
 
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Thread Starter

Mariusz777

Joined Apr 2, 2021
9
You're jumping all over the place. Is your goal to figure out if your idea is feasible, or to prove that your idea works from a technical perspective, or do you know your idea will work and you want to hire someone to build it?

Proof of concept builds are absolutely a good idea, and before designing custom hardware. Use as much off-the-shelf development hardware as possible to prove that the idea is technically sound, then worry about custom hardware. What stage are you at? Are you sure your idea is technically sound, or do you still need a proof of concept to prove that it works?

In regards to your question about requirements for software; on the projects I've worked on, all of the specifications are in the same product requirements doc, both software and hardware, and the company that I worked for handled both. We had software guys, firmware guys, hardware guys and mechanical guys, it was a one stop shop. You can certainly split it up and take it to different places if you like, but it may be a lot simpler to have it all done under the same roof, if you can find a company that can do it all.

If you know ahead of time that you are going to need some specific test points then they should be specified in the requirements doc. During development it may become apparent that additional test points would be helpful and they can be added.
Sorry for digging deeper into it. What I am trying to find out are the processes involved in the DFM and be able to draw some plan for a simple product.

Regarding the idea and feasibility of the design I understand the processes - thank you. I also get the proof of concept (prototype) process as well.

I come from manufacturing and testing industry and at the moment researching how the processes differ. I have never worked in design before yet I would like to find out all the steps required in the design of a simple product- what are the phases and documentation required. I know I jump from one to another a little bit - sorry about that.

Can you tell me what happens after prototype is build, tested and its functionality is verified against the requirements. Lets say everything has gone smoothly and there were no hiccups in this stage the prototype has been approved and we have a green light from the management to move to the next stage.

To my understanding the next step would be to develop the schematic and produce the BOM. Inform purchasing department about materials/components required (purchasing order) skipping ERP system (there is no product yet hence no entry in ERP).

Than while waiting for components development stage of PCB can take place. It can take anything between 1 to 4 weeks depending on the complexity of the board its density, components used, amount of layers, screening for EMC, enclosure type etc.
Since first run boards lets say 5 are tested and verified by the design engineer no manufacturing assembly manuals are required yet, however software tests would be, starting from unit test through blocks to system test.

Assuming my understanding is correct the next stage would be to produce test specification based on the measurements and characteristics obtained from the boards. At this stage all the test points and operational conditions are addressed as the specification can be used for ATE equipment development (i.e. bed of nails) for massive production.

Am I correct assuming these would be the stages?

The stage of prototyping can be explained as a loop with continuous improvements and fixing any bugs during the process i.e. refining the design.

When prototype stage has been completed and we have a working populated and refined prototype - where to go from here? what is the next stage?
 

MrSoftware

Joined Oct 29, 2013
2,015
It sounds like you're looking for an official specification as opposed to someone just telling you how they've done it in practice. Maybe look at ISO 9001 and see if that's what you're looking for.
 
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