When designing a PCB, the decisions can have a significant impact on the ability to manufacture the circuit board, such as significant cost increases, slower manufacture or even the inability to manufacture at scale.
Considering the lifecycle stage of the components and identifying those prone to allocation are important steps. Specifying alternative drop-in replacements can also help with risk mitigation in the case of unexpected supply chain shocks.
Very small packages like tiny passives and fine-pitch BGAs (Ball Grid Arrays), can require re-working placements and further inspection to ensure they can be manufactured reliably.
Increasing the amount of PCB layers helps with flexibility on routing but often adds cost and complexity into manufacturing.
Combining SMT and THT and specialist components can lead to additional manufacturing stages which can add significantly more cost than the straightforward assembly process.
Large numbers of unique components, suppliers or types of packages can rapidly increase risk, especially in an industry known for its volatility and supply chain instability. This often impacts procurement, kitting and setup. This can be avoided by selecting (where possible), components which have drop-in alternatives already available on the market or cultivating alternate suppliers in case of a supply chain shock.
Densely populated boards can cause a number of problems in manufacture, including placement difficulties, soldering, rework and inspection challenges which could be mitigated by a better initial design to allow for these to be done in the first place.
While double-sided assembly can look attractive, it can easily lead to increased complexity in assembly and potentially lead to additional reflow stages needing to be built in.
This is important when designing a circuit board for manufacture. Large copper areas, components with large differences in thermal mass, thermal pads and heatsinks can all affect soldering and reflow profiles.
Although often overlooked in favour of optimal assembly, this can become a problem later when looking to test or inspect efficiently.
This can impact the efficiency of assembly and can also affect handling and panelisation, increasing the cost and complexity overall.
This includes, blind, buried and via-in-pad designs which can be necessary for complex boards, but come with an increased difficulty to manufacture than more conventional through-hole vias.
Unnecessarily tight design tolerances can also become a problem for manufacturing, especially when there is no real overall benefit to the finished product.
Having reviewed the key considerations regarding board design, which is relatively well known, we can consider prioritising those which are likely to make the largest impact and begin to look for solutions.
The level of impact can vary depending on what you are trying to achieve through the design of the PCB, but we at Colmworth look at the four most common high impact considerations:
Component selection and availability deliver the highest impact generally. The circuit board can be perfectly designed but if the components are obsolete, suffering from long lead times or are otherwise difficult to source, the design can’t be executed and therefore doesn’t matter.
Many designers don’t place the same emphasis on this compared to more technical considerations. Having a secondary/alternate supply readily available helps to alleviate the risk of over-reliance on single suppliers, especially in the case of supply chain disruptions.
Implementing DFM (Design for Manufacturability) principles at an early stage can bypass a lot of the problems, especially related to manufacturing issues. Ensuring the spacing is well designed for manufacture, inspection, and testing is helpful. Additionally, avoiding miniaturisation where possible and prototyping before volume manufacture helps to mitigate some of the challenges.
Using standard through-hole vias, avoiding via-in-pad where possible, simplifying the PCB stack-up and keeping the layer count low are all good ways to reduce manufacturing complexity.
Additionally, avoiding unnecessary double-sided PCBs along with mixing SMT and THT tend to add manufacturing costs, including additional process steps and additional equipment.
For help with challenges sourcing alternate components, mitigating supply chain risk, kitting, PCB design and assembly to deliver optimisations, contact Colmworth Electronics today.
Call or email our team and our experts will assist you with optimising your PCB design and manufacture.
Email: sales@colmworthelectronics.co.uk
Call: 01480 477400
