DAC32 PRODUCTION INSIGHTS
We are stating on multiple occasions that all of our products are fabricated in-house. This gives us maximal design flexibility and also the chance to act quickly on market changes like increased demand or the introduction of new features.
Although e.g. DAC32 looks pretty simple to manufacture it is not trivial. There are many steps required and in the end over 100 single components need to be put together in the right order and with the right quality.
It all starts with the naked printed circuit boards we are sourcing from a specialist supplier. Four DAC32 PCBs are put together and surrounded by a 5 mm tooling frame. This is a so called production panel. The purpose of this mainly is increasing throughput in the following steps. The tooling frame itself is added so that the boards can be handled by the machines described below.
At first on each panel solder paste is applied using a special stainless steel stencil and a a manually operated fixture. This paste will hold the surface mounted components (SMD) in place and in a later production step will melt and solder everything together.
Next step is the pick and place machine. It is some kind of robot that will put all the single component in the right spot. Two special cameras, four nozzles, 48 tape feeders and a conveyor will do the job. Most of the components come on special reels which the tape feeders un-reel and then the head with the four nozzles will come and pick up the components before they are being places on the board.
Afterwards the boards are being manually quality inspected. In rarely occasions it can happen that single components weren’t placed correctly by the machine. At this stage it can be easily corrected by hand.
If the boards passed the manual optical inspection (MOI) they are being put into our conveyor reflow oven. It’s like a large pizza oven that has multiple temperature zones. For the solder paste to melt properly a special reflow temperature profile needs to be used. See the diagram below. First there is a soaking window and then it needs to be ramped up to the peak soldering temperature before it needs to be ramped down again to not damage any components.
Once the boards are out of the oven they are being broken apart in the single DAC32 boards. Now there is another manual optical inspection followed by hand soldering the through-hole (THT) components.
Although the board is completed now it still won’t do anything when connected to power. For this the firmware needs to be uploaded and also it needs to be tested for general functionality and audio quality. For this we built a special “flash & test station” where the boards will get the latest software and also tested automatically. In the beginning we were doing that manually which was very time consuming. This nice device helps us with reducing the production time quite a bit.
At this stage the electronics are fully functional. Nevertheless of course something is still missing. The housing.
As a basis for our housing we are using an off the shelf part made in the US. We are using our CNC mill for cutting the openings in the backside. For this we developed a special tooling frame where a couple of them can be put in and then the machine does it’s job. In the front side there also is a tiny hole for the status LED. This one is drilled by hand using a small fixture.
In the early days of DAC32 we were using the laser engraver for engraving the two labels (top and bottom side). Nevertheless that was pretty time consuming and didn’t scale well. So we have outsourced this and are now using professionally printed labels.
So at this stage the labels are being glued down on the top and bottom side. Especially the bottom one is a little tricky as there is no guide to properly align it when gluing down. This was solved using a 3D printed fixture where the label is applied and then pressed agains the housing. The four holes for the feet will help aligning it.
What is still missing? Of course the rubber feet. We could save quite some effort if we would just use self adhesive feet. Nevertheless they tend to fall off after some time and we are only building sustainable products. So we are using press-in feet that are being pressed into the four holes on the bottom that were previously drilled using a fixture. Also those feet will prevent the backside label becoming loose as they are pressing against it.
The final step is putting everything together. There are four screws that are holding the electronics in place as well as two other screws that are holding together the housing. For assembling it we are using a special tool that will always tighten the screws with the same torque.
Now look at this beauty. One could think it is ready to be shipped out – but it isn’t. We are still missing the power cable, the quick start guide and the packaging.
Let’s start with the cable. That’s easy as it’s bought from a supplier and we just have to pout it into the box. The box itself is delivered from an external supplier but it comes flat – so still needs to be folded. At this stage the most time consuming task for us currently is the fabrication of the quick start guide. Many pages need to be printed, cut, folded, and stapled together. We are looking to outsource this in future but for the time bing it’s still hand made.
Once the DAC32, the quick start guide, the cable and the packaging is ready a serial number gets assigned from our ERP system. This number is hand written onto each DAC32 and also contained on the label that attached to the packaging. Once this has been done everything is being put into the box, the packaging labels are applied and it gets sealed with a special tamper proof sticker.
Only now DAC32 is ready to be shipped out. As you see a lot of work is involved even in a device that does not look too complicated. And that was only the manufacturing part. Developing it is a story for another day.