Mechanical and Electronics Design Is Converging. It Has To.
John Hayes posted on October 27, 2018 |

Electronics is getting to be such a big part of a product’s design that a purely mechanical product has become a rarity in our modern world. But the interplay between mechanical design teams and electronics design teams can be anything but straight forward. It is a situation that often delays successful product launches.

The physical form of the electronics must be carefully considered in the product design. For example, take a printed circuit board (PCB). The typical workflow involves an electronics designer working with one design software while their mechanical counterpart designs the enclosure with a different software package.

This FLOWdometer from SweetSense, shown on a soldering fixture,shows a common task for the mechanical designer: fitthe PCB insider the cavity. The desire to make devices ever smaller leads to multiple iterations between electronic and mechanical designers. (Picture courtesy of SweetSense)
This FLOWdometer from SweetSense, shown on a soldering fixture,shows a common task for the mechanical designer: fit the PCB insider the cavity. The desire to make devices ever smaller leads to multiple iterations between electronic and mechanical designers. (Picture courtesy of SweetSense)

Taylor Sharpe is a mechanical designer at SweetSense, makers of sensors that monitor critical water infrastructure in remote parts of East Africa. He described the delays that result from a work flow that goes back and forth between electronics and mechanical design. “Our electronics engineer would design a board and send it to a 3rd party to create a prototype,” says Taylor. “We’d get the prototype and it wouldn’t fit into the enclosure either because the electronics designer added something or because someone on the mechanical side changed the enclosure. This back and forth added lots of delays to the process.”

This problem gets more critical as electronic designers, software developers and mechanical designers are forced to work ever more closely on product releases. In a recent engineering.com survey, we found that a “typical” mid-size design team now consists of 3 mechanical designers, 3 electrical/electronic designers, 2 software designers, 2 systems designers and 1 industrial designer.

A typical product design team consists of 11 members, including specialists for mechanical, systems, industrial, electrical/electronic and software. (Source: Research Report: Integrating Electrical and Mechanical Design. Do Product Teams See Value?)
A typical product design team consists of 11 members, including specialists for mechanical, systems, industrial, electrical/electronic and software. (Source: Research Report: Integrating Electrical and Mechanical Design. Do Product Teams See Value?)

Anything that vendors can do to streamline the workflow between the various disciplines without having to resort to file translation is a STEP (pun intended) in the right direction.

CAD vendors are working towards supporting integrated electrical and mechanical workflows. Siemens PLM bought Mentor Graphics in 2017 and now offers electrical and electronics design within their CAD packages, NX and Solid Edge. SOLIDWORKS has had an electrical design software for many years and also partners with Altium for PCB design. Similarly, Autodesk acquired EAGLE in 2016. All of these software vendors are striving to create bi-directional associativity without file translation to smooth the electronic/electrical/mechanical workflow.

Autodesk recently announced enhancements to their integration between their Fusion 360 cloud-based mechanical CAD solution with EAGLE, their PCB design tool. Sam Sattel, Sr. Marketing Manager at Autodesk claimed that EAGLE is the most popular PCB design tool in the world, with “millions” of users of its free version. The free version allows teams to design boards of up to 2 layers.

Sam says that since the acquisition, Autodesk has been working diligently towards true associativity between Fusion and EAGLE where, “a change on either side informs the model on the other side,” although he concedes “it’s not all there yet.” For example, the mechanical model in Fusion 360 does not understand the layers of the board.

Also, all of the electrical simulation and electronic design is done in EAGLE. That said, the integrated suite now supports importing board outlines from Fusion 360 to EAGLE or EAGLE to Fusion 360. It also lets users update their placement of components on the board in EAGLE or Fusion 360, and populate each component with a 3D model. This makes a lot of sense for teams where the responsibilities for electronic and mechanical designs are starting to blur.

Sam referred to common problem with placing mounting holes. “Typically, an electronics designer might start their design with a few constraints from the mechanical designers, such as the size of the board, placement of critical components such as an HDMI plug, and mounting holes,” he said “The mechanical team then carries on as though the electronics team will be able to match those constraints, but to do so, the electronics designer might have to move a mounting hole. Or the mechanical designer might have to move a major component just a little bit.”

And then the fun begins…

A Fusion360 designed FLOWdometer enclosure including a PCB designed in EAGLE. (Picture courtesy of SweetSense)
A Fusion 360 designed FLOWdometer enclosure including a PCB designed in EAGLE. (Picture courtesy of SweetSense)

Sattel pointed out, “With the improved EAGLE/Fusion 360 integration, any change in one model informs the other model. The designer can choose to accept or reject the change. Say you are working in EAGLE and there has been a change to the mechanical model. You are informed of the changes via a text-based slide-out that tells you what has changed with a reference to where it is.”

“In the other direction, the notification is similar, but a little more elegant. The user is notified of the update and invited to sync the model.”

In this video demonstration, the designer designs the board outline in Fusion 360, including mounting holes, and passes the design to EAGLE where the components can be placed. The demonstration also includes some back and forth design changes, pushing from one package to the other.

According to Taylor of SweetSense, this functionality in Fusion 360 has been “a game changing enhancement” to their design workflow. He now builds the enclosure models in Fusion 360 with a PCB outline. “If the electronics designer makes any changes, it auto-populates in the mechanical model,” he said. “We are now finding mechanical interference much faster than we did through prototyping. It also lets us explore unique mounting approaches to fit the enclosure as tightly as possible around the board electronics.”

“Using an integrated electronic/mechanical tool like Fusion 360 with EAGLE has cut our overall cycle time by 50%, give or take,” he added. The findings of the engineering.com survey support that comment. Fully 72% of design teams said that they could reduce their development cycle time with integrated electrical and mechanical design tools.

EAGLE and Fusion 360 are still two separate software packages. Nirvana would be a single package running on a common database, offering customized menus for each discipline. That requires a cloud-based product development environment that stores and syncs all of the data. While many software vendors appear to be heading in that direction, a completely integrated suite of tools stays just over the horizon. In the meantime, we can certainly benefit from the progress design vendors are making towards this goal.


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