Last year at Lumos, I have gone through full hardware development
process and when I look back, I have learnt a lot about the product development. I
realized that I should share my experience with fellow hardware
entrepreneurs.
Again, this is from my limited one year experience and few
other leanings might yet to happen. Consider this blog for only simple or medium complexity consumer products.
Design Process
Here, It is assumed that you
have the product idea and you have limited knowledge about product development.
My product development process is matching
this
to a large extent. But, the article looks at it from business perspective while
I am putting it from engineering perspective.
Proof of Concept (POC) :
Proof of concept is a dirty prototype of the core functionality.
Don't try to accommodate extra features. Generally, proof of concept is making
the product using Arduino, raspberry-pi, General purpose PCB (GP), breadboard
etc.
Why should you do proof of concept before starting product
development?
- Help you establishing technical feasibility. Lot
of time, you assume that two kind of products are available and your idea is
just fusion of both. But, in reality, it might be not possible technically or
it might be significantly complex to implement.
- Help you understand important technical
components very well. i.e, you might assume that you just need to use a camera
for your product but during the POC, you need to set 100 parameters for camera
function. You need to understand camera well before configuring these
parameters.
- You have something in hand to understand
customer needs. You can judge customer's interest from this. You can talk to a
customer about importance of a particular feature. Also, you get sense of what
other features are required to make it complete products etc.
- With your initial customer feedback and some
idea about complexity, you can start drafting the specifications.
- You can show the POC to a potential investor
(your uncle or an angle investor or your manager!!) and try to fetch some seed
money. Without POC, no one is going to fund your product design activity (ignore
if you have rich parents or you are rich parent !!).
- More than above all, you get confidence on
technical feasibility and market existence before you start spending huge
money.
End outcome of the POC are many. Most important one for
product development point of view is specifications of the product. During POC
phase (or end of it), you would have interacted with at-least 100 potential
customers and know their requirement (Yes, 100 is a random number :P. The
number depends on type of market and customer segment). You should able to
create a list of customer needs and put them into these 3 buckets.
- Must haves : Required by all potential customer
segments.
- Optional : Required by some of the customer
segments
- Lateral
The lateral needs (features based on it) are very important.
These are not asked by any customer but you think it would delight them. The
product needs to be well thought and lateral features usually create extremely
satisfied customers.
Now after this, you can study competitor products or
solutions also to understand what customer needs they are addressing. Lot of
time the customers you meet forget to tell one of 'must haves'. Looking at
competitors might help here.
After you draft the needs, start drafting the
specifications. Consider both customer needs and complexity involved in
implementation. Try to define the "To manufacturing" time (deadline
for product development or design closure) along with specification of
the product. A good approach is to launch first product with minimum required
features and keep adding features on next version of the product. This might help in staying ahead
of competition.
My master project guide
, Dr. Andre Pittet,
used to suggest to go for 'wish specification' first and then cut down the
features based on time availability and complexity of implementation.
Also, your customer development team should get feedback from the customer on
each feature.
Your specifications needs to be complete. Everything from
operating temperature, humidity level to amount of mechanical load it can take
should be specified. Do specify target
cost also.
This is Lumos charger specification for example.
FAQ on POC
My complete solution includes cloud connectivity, storage and visualization too. Should I get it up at POC level ?
No for most of products. If you get the data on serial terminal of the PC is good enough. ( Beware, I am biased here, I don't appreciate complexity of putting data from serial terminal to cloud, making it secure, giving nice visualization etc.)
How much time do I need to spend of POC ?
Typical time for simple or medium complexity product is 1-3 weeks. Most of this time goes into the component procurement. You might just spend 10 hours for it.
But, if you are developing a device which measure blood pressure just by holding it in palm(complex technology) then it requires good effort. Specifically because it is not proven technology and requires testing on multiple kind of people.
Do I need to talk to customer before writing specification ? Apple never does any user survey and develops amazing product, why can't I ?
I won't go into whether Apple does the user survey or not here. They are product genius and know what user need very well and deliver beyond user's expectation. But, I would recommend doing customer development (which is little different from market survey, read the startup bible 'the lean startup' to understand what is it) before start putting heavy money and time. They main reason here is that in most cases the founders don't represent the customer segment or founders are the only customers who need the solution. Talk to few hundred potential customers before quitting your MNC job.
Instead of customers, can I talk to some retailer of similar products who will be selling my products to customers ? They know the customer segment and their requirement very well.
Yes, do talk to them. But, never assume they know all customers requirement or represent customer segment. i.e. If you are developing home automation system, which you are going to launch with leading builder. You understood all the requirement from the builder but never talked to any home buyers (potential users). This will lead to low market acceptance because the end users are not going to be happy.
Design Phase :
Design phase start with detailed specifications and end with
a product which you need to exactly replicate. It involves all design for
manufacturability, certification consideration. Typical timeline for this is 6
months to 3 year. Best way to quicken the development is to stop changing
specifications too often.
For electronic product, there are mostly two design
activities, electronics design and mechanical design. You might have few more.
i.e. we have the fashion design activity too.
Here, I am assuming that you have the block diagram of your
solution. I won't address much on how to find good solution for the problem you
are addressing.
Electronic Design Activity :
The process chart is
self-explanatory. The first 3 steps, part selection, schematics design
and PCB design go together so indicated in different color, same way the last
two. Very important consideration here
is that, you will have at-least two
revisions of above process. Some time you need 4 or more revisions because
small inaccuracies. Electronic design
needs focused mind !!
Important Parts selection
After specifications, you start with important and critical
parts selection. This involves your camera or any other sensor,
micro-controller, battery, power regulators, battery charge controller etc. This
is most critical part of design phase. I recommend to start putting these parts
into the schematics also.
While doing the part selection, with keeping eye on the
functionality, Keep eye on following parameters also.
- Cost
- Error budgeting ( What would be worst case error in measurements)
- Power calculation ( based on datasheet numbers )
- Future upgrades(You can add complex software or add the 'wish features' later).
- Selected part's market life ( the part you selected might get obsolete before you go to manufacturing)
- Certifications ( I am going to address certification in a separate blog)
- Design complexity
Here are few tips for part selection
- Design support (reference design, application
notes, forums, software support) is important consideration for each part
- Involve the component distributor like Avnet or WT from start of your design. They
will make sure you get all required support.
- Get quote for 1000 numbers to estimate the BOM
cost
- You will at-least get half of the digikey price
for 1000 quantity (from distributer like Avnet or from China)
- If you are getting component like battery from
China, make sure you ask for the certificates (MSDS, UN 38.3 etc) upfront. May
be before placing the sample order.
- Before selection microcontroller find out the
development tool cost i.e. TI has excellent BLE chip cc2540/CC2541 but TI's
pre-compiled libraries for BLE stack is available for IAR only. IAR license
cost few lakhs !!
- Prefer ARM based micro-controllers. They make
your system scalable and they supports GNU tools.
- If you have complex functionality, get the EVM
boards and test your functionality on the EVM board.
Schematic Design
After you have selected critical part, schematic design includes
passive component selection, doing power calculations, cost optimization,
selecting ferrite beads and provide provision for future expansions. I am
putting some basic tips and learning.
- Follow reference schematics or EVM schematics to
extend possible. If you are not following any of IC manufacturer recommendation,
think it well and test it well.
- Provide provision for EMI/EMC related components
like common mode inductors at all your power inputs.
- Provide ESD protection at all the ports where
humans can touch. Don't overdesign. Cost increase significantly with your
specific requirement. i.e. think thrice before you use tantalum capacitor.
Check if it is really required.
- If you are selecting passives and planning manufacturing in India. Make sure all you get from India. You will get all resistor and capacitors at Micro-components SP road (phone : 98451 57490). Micro-components get all components from 'Yageo' so quality is ok.
- There is one digikey equivalent for India : comkey.in. Check it out. Could get all connectors and inductors from here.
- Wurth Electronik is one of the best supplier for magnetic components. They are not dam cheap but be sure about the quality. Advantage with Wurth is that they are the only big manufacturer without strict minimum order quantity restriction. Their India team is very energetic and supportive.
- Capacitor cost 0.5 rupees per piece (for
quantity of 100-1000) unless you have special requirement i.e. 47uF in 0805
package
- Resistor (1% or 5%) cost 0.2 rupees per piece
(for quantity of 100-1000) (specific low value or higher power rating cost
more)
- Get the schematics reviewed by many people.
PCB Design
Steps for PCB design are following.
- Make or get footprint of basic components. If you make the footprint, get it verified with other team members.
- Get mechanical layout from the industrial/mechanical designer. Which includes PCB size, position of all the connectors, LEDs, Switches etc.
- Floorplan the components from the mechanical design and routing patterns.
- Decide the stack-up of the PCB. This include how many layers of routing, copper thickness, PCB core material type and thickness.
- Get all schematic net's maximum current and maximum voltage and out it up in an excel. This will define your routing trace thickness(current) and spacing (voltage) .
- Route it
- Get it verified from third person
- Generate gerber and release to manufacturing
It is
very difficult to give generalized tips on PCB design. Here are few tips.
- If you can, go for only one sided component
mounting. It saves the assembly cost.
- Check what minimum trace width your supplier can support
- Before you select the passive package size, check the cost factor
- Follow the IC manufacturer's layout guideline thoroughly
- Try to get one not disturbed ground plane without any traces. You can merge analog and digital ground in this plane. Approach here is to minimize ground resistance so that digital current can't create ground noise. Not disturbed ground plan help on EMI, EMC also
- Decide PCB board manufacturer now itself to design up to his capability.
- Make sure design has taken care of the manufacturing tolerances. Sometime the PCB cutout tolerances cause problem of the board fitment in an accurately designed enclosure.
- Be sure of what kind of surface finish you want. Generally popular one are HASL, lead free HASL, ENIG, OSP and gold. Read about each of them and wisely choose one. Very few manufacturer support OSP in India. But, it is one of most cost effective and good quality solution for mass production. Make sure your PCB assembly manufacturer is ready for OSP.
Prototype Manufacturing:
Manufacturer your designed board !! Generally we prototype
10 boards.
Good prototype manufacturer : PC process Penya, Bangalore or PCB power, Gandhinagar,
Gujarat
We don't make stencil at this stage. But, if you have
complex PCB, you might have to do that. We do manual mounting and soldering.
for complex PCBs, you might have to go to EMS.
Generally, we follow board bring-up method for PCB assembly.
In board bring-up we mount components in stages and check the functionality in
stages. i.e. mount first the power
components, check if intended voltages
are present at the not mounted IC pins, followed by micro-controller and then
sensor.
Software development
Yes, now your board is up. Start developing the software.
Lot of time you would like to start the software development on EVMs or
reference boards. No generalized tips here other than be careful while porting
software from one board to other board.
Testing
One of the most important part of design cycle is testing or
design verification(DV). If you are a consumer company, this becomes extra
important for you. You should make sure that your product works without any
bug.
There are many DV approaches. Take any approach but make
sure you have detailed testplan and all test are performed. Some physical test
like drop test, over temperature, short circuit at output also need to be included.
FAQ on Electronic Design
Why do you say that
there would be at-least two revisions of the PCBs ?
Because product development is complex and you don't have
good simulation tools. Many parts of design are going in parallel and mistakes
are likely to happen. If you have done similar product with same parts previously
then there is possibility that one revision is enough.
One thumb rule is that when you can't explain what is
problem with your board to your business co-founder and he insist that not to
go for any revision now, then you are going for the last revision.
Why is board bring-up
method is preferred in prototype manufacturing ?
If you get fully assembled board from your EMS and start
testing it, mostly you will see IC heating up or capacitor burning. If not, you
will have an issue which will make you nuts debugging. Irrespective of where
you do assembly, make sure your functionality is getting up one by one.
Mechanical Design Activity :
Mechanical design/ Industrial design is most important part
of your product. Users interact with it more than your underlying electronics.
It is very important aspect if you are making a consumer product. Also,
manufacturability is much more complex here that an electronic part manufacturing.
If you don't have any one to design the mechanicals then
get a good industrial design firms.
Typically, an industrial design firm has an industrial designer who handle
studying user requirements and creativity and one mechanical engineer who
understand manufacturing processes and materials. Industrial designer,
mechanical designer and electronic designer should work in synergy. Here is simple process for mechanical design from
an electronic designer point of view.
- Understanding User requirement
- Create few early sketches
- Understand engineering requirement for each sketches
- Make early cad
- Review early cad (by the CEO and entire team)
- Go for final CAD with DFM consideration
- Go for 3D printing and find all issues (PCB fitment etc)
- Iterate to point 6
- Finalize the CAD
- Create guidelines for mold manufacturing
- Go for production
Some last steps before design closure
- Certifications : I will cover it in my next blog
- Design for manufacturing check : get it checked with experienced design for manufacturability person. Ask feedback from your manufacturer.
- Setting up quality process (what points voltage/current needs to be measured to make sure all components works)
Manufacturing
This is a vast topic and general tips won't make sense much.
Take all data mentioned here with some doubt. Match your product with our product
and see all tips given here make sense for you.
Mechanicals Manufacturing
This process is much complex than electronic manufacturing.
If you are going for injection molding, the major complexity is to do mold
manufacturing. Generally, molds are costly. Good manufacturer quote >4 lacs
for any size mold. Here are few things are learned.
- If your target quantity is <10000 unit. Don't do mold. One way is to avoid injection molding totally buy using metal enclosure or off the self enclosure.
- There are some manufacturer who can give prototype exactly looking like injection molding prototype. 3DPD and cycloid do that as per my knowledge. P.S: I have not tried this yet.
- One other option is protolabs, which supplies CNC machined components for low volumes.
- I refer this mold manufacturer, Tamam components, contact them on tamam2010@rediffmail.com. They are cost effective and reliable on lead times. Part quality is also ok.
- Don't assume that once mold is done, you will get exact parts. There are variations like molding time, pressure and temperature. Make sure that you go to manufacturer place and do experiments to get best combination. If you can't do this then get help of some experienced person. This is very important step for quality assurance.
Electronics Manufacturing
Electronics manufacturing is reliable if your EMS or PCB
assembler follow the standard quality practices. Wait for my blog where I
explain all layers of PCB and PCB manufacturing and assembly process. Here are
some simple tips.
- Don't forget to lock your code after
programming. Some-one can read and copy your product as it is.
- Make sure you visit the PCB assembler's factory
- First make one board and test is well before
going for mass. (To make sure that pick & place machine is programmed
correctly)
- Quality test must happen at PCB assembly
manufacturer's place
- Define maximum failure rate with your PCB
assembler before you place Purchase Order
- Go for pilot production (100 numbers) before
going to mass ( > 1000)
- Managing working capital for manufacturing is
not easy task
- Make sure that final assembly process (putting
PCB into the box) happens accurately.
- Don't go for 100% manual assembly process.
Manually soldering through holes are ok but SMD components assembly must happen
through reflow. There are does manual placements, which creates lots of failures.
- PCB board typical lead time for mass production
is ~2-3 weeks
- IC components lead times are in the range of 6-8
weeks
