Riotee

An open-source platform for the battery-free Internet of Things

May 02, 2023

Project update 5 of 7

Production Progress

by Kai G

It’s been one month since the end of the campaign, so we would like to share with you the current status of the project.

We are currently waiting for the transfer of funds from Crowd Supply. But, because we know you want to get your hands on Riotee as soon as possible, we decided to pre-finance production and get started now.

Here’s the current status of each individual product:

We did factor in multiple weeks of unexpected delays when planning the timeline for the fulfilment of the campaign. Therefore, despite a number of obstacles and delays, we are still on schedule and aim to deliver the first batch of products to Crowd Supply this month.

Challenges

We were faced with two challenges regarding series production of the Riotee products: The first challenge concerns the Riotee Solar Shield. The shield was supposed to be equipped with four KXOB25-05X3F solar panels. For as long as we’ve been working with these excellent panels, many thousands had been in stock at Digi-Key so we didn’t worry about them. But just as we were getting ready to place the order, they sold out on Digi-Key and we had to find an alternative. Luckily, the KXOB25-03X4F was still in stock. The panel has the same footprint and only slightly different characteristics so we can use it as a drop-in replacement.

The second challenge was with one of our manufacturers who was supposed to assemble the Riotee Modules for us. This manufacturer had previously built prototypes of the Riotee Module without problems and sent us a quote for the series production in January. But when we had a meeting to discuss the details in mid-April, the production manager was concerned that no automatic optical inspection would be possible after the EMI shield is placed on top of the Module.

They offered two solutions: A blind production run without optical inspection or a two-step assembly, where EMI shields get manually soldered onto the Modules after optical inspection. The first option may lead to an increased number of defects, some of which could be hard to detect reliably during final testing. The second solution is extremely expensive, since every single module would require manual attention.

Disappointed with these options, we contacted another trusted manufacturer in Dresden, Germany who we’ve worked with before. We sent them the production data and asked them if they can offer a better solution. And indeed they could! Unlike the first assembly house, this manufacturer uses a jet printer to apply solder paste before assembling the components. This allows for an automated, two-step assembly process with intermediate optical inspection: First, paste for the components is applied, components are placed, and the PCBs are soldered in the reflow oven. Next, the PCBs go into optical inspection to detect any potential solder defects. After passing inspection, the jet printer applies another round of solder paste to the area where the EMI shield will be placed. The EMI shield is placed in the pick-and-place machine and the PCBs run through the oven a second time. This way, assembly should be reliable with an expected failure rate of less than one percent.


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