Hi,
We started by removing all thru hole components and eliminating all components that we don't really need in a production environment (some LEDs for debugging, headers for testing, some connectors for easy external access).
This will have an impact on the board layout / size and number of components. (It's a double-sided 4 layer PCB).
In terms of the overall cost of manufacturing a PCB, what are the major cost factors that we need to take into account ?
We have a clear view on the price of the individual components and a rough idea on the price of the PCB, but what determines the price tag associated with putting the components on the PCB (pick and place / reflow / ......) ?
I can imagine that the following items an important role in the actual cost:
- the number of components on the board
- the different type of components
- single / double sided board
- all SMD components
- size of the PCB (?)
- the quantities (obviously).
What else can we take up in the design that would help lower our PCB manufacturing cost ?
Thanks...
The items you listed are indeed the major ones, especially board size and quantity. I hope you are asking your pcb supplier in addition to this forum.
Additional items that directly affect pcb cost and items that affect assembly cost might include:
- can you panelize your board so that you are running more than one at a time through pick&place?
- is your pcb or pcb-panel using the available area of a blank panel efficiently (
https://pcdandf.com/cms/home/246-2012-articles/9058-panelization )
- can you take advantage of low cost methods of separating your individual boards from the panel, like using v-score instead of routing
- does your board have slots in it that need to be routed. slot routing costs money.
- does your board include controlled impedance traces? Why? they cost more than not specifying them
- do you have via-in-pad? Why? These can cost more if you specify that they be filled.
- typically, costs go up as the number of holes go up, if the hole sizes include very small ones like less than .016in dia
- typically, costs are higher if you have very fine spaces between traces, or if you have very fine trace widths (for example, spaces/traces less than 0.008in start to add to cost)
- what surface finish is used. HASL is typically cheapest as opposed to ENIG for example.
items more pertinent to assembly and test costs:
- are you careful to limit yourself to easily handled smt part sizes, for example using 0603 or 0402 resistors while avoiding 0201 sizes. Or specifying TSSOP ic package rather than QFN or other leadless types?
- it might be a bit early to remove your engineering components unless you're entirely happy with functionality and performance
- what kind of electrical tester will be used for functional test? Adding probe test points may allow use of a higher speed tester or a lower cost system.
- have you scrubbed your design with an aim to reduce the number of unique resistor values, capacitor values, inductor values, ic types?
- do you have any components that are unusually shadowed, that is, a tiny part right next to a very large part. Or parts literally underneath other parts. This may require more tuning of the solder process.
- is your documentation crystal clear, accurate, and dummy-proof? Something like could cost you time and money if mistakes are made during assembly. Are you providing all the necessary assembly information that could possibly be needed including special handling notes?
- can you avoid unusual soldering requirements like high-temp? How about board cleaning, is no-clean flux ok for your parts?
- are you avoiding special handling of the board after assembly by ruggedizing it against ESD damage?
- are you using simple methods to attach your pcb to its chassis or housing? Can you use snaps rather than screws? Is your final assembly simple, for example all in one direction? Are you able to avoid multiple pc assemblies and inter-board wiring?
- are you ensuring sufficient tolerance in the location and diameter of your mounting holes?
- have you avoided having more than one electrical connector between boards so as to avoid addition of location tolerances?
- are you using the cheapest possible method of heatsinking your hot components?
- do you avoid handling costs by doing pcb assembly and final assembly in one location? Or do you ensure best quality by doing pc assembly in one location and final assembly and test in another (ie. your own shop)? The latter is preferred when doing your initial low volumes. Keep you final and especially your testing close for now.
- minimize your warranty and yield costs (and save your reputation) by meticulously policing the soldering quality of your assembly operation. Do detailed inspections (microscope examination, x-ray etc.) using IPC standards as reference and be aggressive with your assemblers if they make dumb mistakes or just do poor soldering. An assembler with a the right attitude loves negative feedback that is deserved, how else can they improve?
- don't assume anything. Assign one of your people to be responsible for assembly quality.
- on the other hand, don't get carried away with reducing your BOM and assembly costs if you are still testing the market. If you don't have a first customer you may be wasting your time. It is often the case that your first customer will want you to change the design anyways. It is often the case that your first product is not the one that goes to big volumes. Don't spend money on cost reduction if you don't have a good reason.