Framework Laptop 16 Deep Dive - Connectors

This is likely our last Framework Laptop 16 Deep Dive before we start shipping, and those of you who ordered one can dive deep on your own. We began mass production of Mainboards last week, which we’ll hold onto as we resolve the last few remaining open items to begin full system manufacturing.

You may be thinking, do we really need a deep dive on connectors? The answer is a resounding “Yes!”, as connectors are surprisingly among the most complex and critical parts of building a product that is slim, durable, high performance, and easy to repair. Connectors are the electrical and mechanical interfaces between modules in the system. They are what actually makes the product modular! Each connector needs to be easy to engage, hard to accidentally disengage during vibration or drop, robust across repeated reconnections, thin enough to fit within a tiny space, electrically sound from a signal integrity and power perspective, readily manufacturable, and cheap. Our most complicated connectors are made up of dozens of tiny formed metal parts in plastic or metal shells. Given the complexity, our preference is always to find well-proven off-the-shelf connectors. However, occasionally we run into unique interconnect scenarios that don’t match anything out there. In these instances, we’re forced to customize our own solutions. With Framework Laptop 16, we developed two of these to enable our new module ecosystems.

Input Module Connector

The first is the connector that interfaces to Input Modules and the Touchpad Module. This is what enables the hot-swappable modules that allow full input deck customization on Framework Laptop 16. From a signal perspective, this one is relatively straightforward. There are only eight pins, supporting up to one amp at 5V and with no signals faster than USB 2.0. However, from a mechanical standpoint, this was exceptionally challenging. The pins are exposed when Input Modules are removed, meaning they have to be extremely robust to handling. In addition, because of how our Touchpad Module engages, the connectors have to be able to handle not just compression force but also many cycles of shear force. All of this has to work within very limited thickness too. We initially started with a spring-based connector (on the left) during our EVT build but found it to be easy to accidentally bend and break the pins. We then quickly pivoted to a pogo pin solution (on the right), working with CFE, one of the world’s largest pogo manufacturers to build a custom solution. Despite being just 0.8mm in diameter, the brass pins are incredibly durable. They are rated to 10,000 cycles and are difficult to damage even if you try to.

Expansion Bay Interposer

The second connector is vastly more electrically complex. This is the interposer that connects the Mainboard to Expansion Bay Modules. This is what enables upgradeability of high-performance modules like discrete GPUs with Graphics Modules in Framework Laptop 16. This has two 74-pin interfaces supporting 8-lane PCIe 4.0 (and potentially higher), DisplayPort, and >10 amps at 20V. These are extremely difficult specifications to meet, and are made even more complex through our requirement to make it an easy connector to handle and cycle repeatedly. We started with the off-the-shelf FXBeam connector from Neoconix that was used in attempts from other brands at making a modular graphics system in a notebook. We quickly found that these connectors (on the left in the image) could only reliably be installed once. On removing, handling, and reinstalling, it was easy to bend or break off the small pins. We then worked closely with Neoconix to build our own customized version of FXBeam (on the right in the image) that is compatible with the same Mainboard interface, but is substantially more robust. The structure hooks the pins into place and prevents them from being malformed by force from any direction. With that, the interposer is safe for handling and repeated cycling, letting you swap between Expansion Bay Modules with ease.

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!!!

Also, interesting to see which connectors you had to replace, and I can see why you decided to put the effort in for better connectors. Thank you for trying your best, looking forward to seeing it myself soon :grinning:

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YES! We’re back!

Love this one. None of this works without the connectors. Sounds like great work, can’t wait to try them out!

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What is the updated value of repeated cycling for the customized version of FXBeam Expansion Bay Interposer?

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Can the laptop charge / be powered via the expansion bay, or is the power in one direction only?

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Welcome to the forum

If you mean can you charge via the USB-C port on the back of the GPU Expansion Bay module, if I recall correctly, no. It’s just for video out, though it does also provide basic USB 2.0 data.

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If you just mean can the Expansion Bay connector itself pass power to the laptop, yes. Something like a battery expansion bay module is possible.

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It’s these connectors, that need to be made available through the marketplace to enable third parties to build input modules and expansion bays for the FL16. I hope this happens at least right after the first dozen batches have been served.

Third parties can already build input modules and expansion bay modules, some have posted designs. That side of the connector just uses gold-plated PCB pads, which any decent PCB manufacturer can do.

I was talking about those, who can’t do PCB-Manufacturing like myself. :wink:
Futhermore it would be safer to have input module / expansion bay test adapters available for security reasons and easier debugging.

Pretty much anyone can order a prototype PCB board. Oshpark is popular with hobbyists. And all of their boards are gold-plated by default. They ship anywhere in the world. Jlcpcb.com is another popular option. FW made example boards with the connector pads that we can use. If you etch your own PCBs at home, for the input modules, I bet you could get away with raw copper pads temporarily.

Framework has a thread that offers input module connector test adapters. I would think they’d offer spare expansion bay interposers for order just on the marketplace not long after the FW16 ships. We do kind of need FW to provide threaded inserts for 3rd-party expansion bay modules, they said they are working on providing them.

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Love these deep dives and the continued commitment to transparency and education! Hoping for a smooth and exciting FW 16 rollout!

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Another one I have come across recently is Elecrow - click on the PCB links at the top. (I’ve just bought a couple of these displays to go with my FW 16 when it arrives). One of the advantages of Elecrow is they offer a number of mailing options, depending on your urgency.

There really is no excuse these days for using breadboards, the cost of running off a one-off PCB is so low these days. Use kiCAD (it’s free, available for Linux or Windows) to draw the schematic and do the layout.

The other aspect is if you are looking at doing anything on the PCIe bus with any serious speed you will need a PCB to get repeatable speed if trying to push the speed limits of the bus. Same with trying to get maximum speed out of USB-C/USB-3, you need a PCB CAD package to set out proper differential data tracks.

Seconding this. It’s great to know that it’s much more durable than the stock FXBeam… but how much more? The Input Module connectors are rated to 10,000 cycles… but no such figure was given for the Expansion Bay connectors…

I really do appreciate the Framework team’s mentality of “This is good!.. but we can make it better!”

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For the Expansion Bay Interposer, have you guys looked into the recent standards that are getting traction in the server and workstation world like SFF-TA-1033, MCIO Mini CoolEdge I/O (SFF-TA-1016 74p) and the other SFF-TA stuff?

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From what I can tell, these are about as large as normal PCIe and SATA connectors, so way too big for a thin laptop.

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