Hardware Reference
In-Depth Information
PTH connectors have more mechanical anchoring for robustness, but the difficulty
and cost of manufacturing will increase due to the extra soldering step.
Consider the PCB color. Green is cheap. White PCBs turn yellow during reflow if
the manufacturer is not careful.
Consider assembled PCB cleaning. Most mass-produced electronics require clean-
ing to remove a chemical residue that can break down solder connections over
time. However, not all parts can withstand a wash cycle. Does your design contain
parts that cannot be washed?
Consider how the end device will be tested. Where are the test points? Is program-
ming required? Do you have to take it outside to get a GPS lock? How fast is the
test procedure?
Is this a kit—that is, will the user put the parts together? Does it require multiple
pieces, such as a board + USB cable + screws?
Does it have printed materials that need to go in the box?
Are you shipping to the European Union? Do all the components need to meet
RoHS standards? Do all the components need to be child friendly?
Is this design double sided? That doubles the manufacturing cost. This is a tradeoff
that is often made to reduce PCB size.
Can the reflow oven handle and not damage the parts on the double-reflow side?
Consider the PCB panel's overall width. Will it fit in the pick-and-place machine?
Will it fit on the conveyor belt of the reflow oven?
Can the part footprints be optically inspected easily during the AOI step? Can the
AOI machine recognize 0603 versus 0402 component footprints?
Once all of these details are figured out, a new production prototype PCB (usually just
a single copy, not yet a full panel) is created and sent off to a PCB fabricator. This produc-
tion prototype is then given to an engineer for verification that it still works as designed.
Such prototypes may also be tested out on beta users. Changes are subsequently made as
necessary.
If no changes are needed, the BOM is evaluated one last time by both the designer and
the manufacturer. An estimated retail price is determined by taking the total BOM cost
plus the estimated manufacturing labor of the design (excluding any overhead costs for
now) and multiplying by 4. That rough retail price is then used to determine whether the
product still makes sense in the market. Is it competitive with similar products, given its
feature set? This moment of truth for the designer leads to a decision being made between
proceeding, going back for another round of prototypes, or abandoning the project alto-
