PCB Design for Sustainable Manufacturing

Key Takeaways

• An overview of sustainable manufacturing.

• Methods manufacturers can adopt to improve operational efficiency.

• Steps to follow for land pattern creation to minimize work duplication and the chance of error in translating manufacturer’s data.

Design for sustainable manufacturing balances absolute throughput with total demand alongside additional practices to reduce waste and environmental harm.

The number of inventions that have provided ample innovation only to fail to stand the test of time is proof enough that one cannot stand still for long in an evolving market. A review of the history of circuit board manufacturing, which effectively began in the mid-twentieth century, reveals that PCB manufacturing has made significant advances, partly motivated by the need for sustainability. Design for the sustainable manufacture of PCBs has environmental benefits and pays dividends for manufacturers who can more easily scale production to save on waste and processing fees.

Exploring Design for Sustainable Manufacturing Practices

What Is Design for Sustainable Manufacturing?

In contrast to most traditional types of manufacturing, sustainable manufacturing design is a broad strategy that extends beyond the factory production line. The emphasis on environmental impact is in-line with thrusts in other sectors, such as the energy and automotive industries, to minimize the harm done to the ecosystem. Ensuring that flora and fauna are not hurt intentionally or inadvertently by manufactured products, their byproducts, or any other step of the manufacturing process is a significant undertaking, but necessary to maintain the long-term viability of the industry.

Arguably the biggest shift in sustainable manufacturing thus far came about with the Restriction of Hazardous Substances (RoHS) directive, which categorically reduced the usage of leaded solders (among other toxic materials). Since most consumer electronics are highly disposable by nature due to rapid technological advancements, the buildup of heavy metals and other dangerous items has resulted in significant localized pollution at waste sites. Banning certain materials (in most cases, there remain exceptions, but these are less likely to end up in landfills) improves the environmental outlook for all, but manufacturing must adjust. For example, the exclusion of lead from solders not only raises the eutectic temperature for alloys, which adds age-related wear to the board and requires more energy, but it also reduces the overall reliability of the solder joint due to spontaneous solder defects like whiskering. While this is less of an issue in consumer electronics due to their aforementioned disposability, it still represents a potential pain point and optimization opportunity for manufacturers.

It’s worth noting that sustainability and efficiency do not necessarily need to butt heads during production. One of the key points for high-volume lots is eliminating extraneous board features (like removing unnecessary vias) and maximizing material usage (like in panelization) to get the most out of everything consumed in the manufacturing process. Simply by adhering to these frameworks, manufacturers have already taken steps toward good stewardship.

Sustainable Manufacturing Design Methods

Sustainable manufacturing design can be viewed as an attempt to best merge the primary concerns of all parties that may be impacted by the creation of a printed circuit: business profitability, community ecosystem, and safety of all involved. Accomplishing this requires adherence to government and regulatory requirements, good business quality, and risk management, and is best achieved by implementing manufacturing strategies tailored toward sustainability:

• Lean Manufacturing - Reducing time to market helps maximize manufacturing inputs and eliminate the excess buildup of product.
• Agile Manufacturing - Having the equipment capability and expertise to respond to market changes quickly minimizes waste and obsolescence by delivering products that successfully balance supply and demand.
• Green Manufacturing - The term applied to production processes that seek to minimize negative environmental impact by reducing waste, utilizing recycling, minimizing natural resource usage, and other practices. 
• Additive Manufacturing - Also known as 3D printing, additive manufacturing creates three-dimensional objects by building layers upon layers. It is a burgeoning technology that often utilizes composite materials. This method is cost-effective and allows for the production of complex and lightweight products efficiently. 

It is 3D printing that arguably holds the most promise for sustainability, for numerous reasons. First, the boards themselves are more readily recyclable due to the materials used and the unique method of production. 3D-printed circuits can also reduce the total amount of conductor material used with point-to-point traces: instead of routing orthogonally layer by layer, a 3D-printed trace can be manufactured as the crow flies. As it is still a nascent technology, 3D printing is invalid for mass production quantities at this time, but continued development is ongoing.

3D-printed PCBs will allow some new design opportunities compared to traditionally manufactured boards.

Incorporating Design for Sustainable Manufacturing Practices

While sustainability may sometimes be given less of a priority than other parameters during manufacturing, any variant of sustainable production can be adopted to reduce environmental stress. Regardless of the complexity of the board or the quantity of production, creating the most effective sustainable manufacturing process requires board design to adopt principles and incorporate steps to support the board building process:

• Work to maximize panelization - Board production is billed per-panel, not per-board. Good manufacturing practices will wring the most usable panel space by rotating and positioning boards. More rarely, designers can use the panelization information as a feedback mechanism to make slight alterations to the board outline if doing so would further optimize the panelization process (e.g., moving from 3 to 4 boards per panel).
• Apply a design for manufacturing (DFM) framework - DFM-level production is concerned with board design that favors producibility, especially when considering scale. The more efficient the manufacturing process, the less overall waste. Additionally, a DFM mindset at the earliest possible point in manufacturing reduces the number of boards produced that are not intended for sale as well as time and money on any associated redesigns.
• Prioritize safety before and after manufacturing - Partner with manufacturers who adhere to government regulations for approved materials and components while taking responsibility for environmental stewardship.

Efficiency measures like panelization also boost bottom-line sustainability by decreasing material usage per board.

Like most parts of the PCB industry, design for sustainable manufacturing is a joint effort between designers and manufacturers. While designers may not have control over every choice made at the manufacturing level, designing with an eye toward efficiency will go a long way in minimizing the waste associated with rework and redesigns. Cadence’s PCB Design and Analysis tools, like the Constraint Manager, support users with customizable DFM and are fully integrated with  OrCAD PCB Designer.

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