L2 card with Ethernet or USB part 2

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Carpentier
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L2 card with Ethernet or USB part 2

Post by Carpentier »

Version: 1
Status: Public release
License: BSD
Download: /files/project_builds/lan.zip

Finally succeded with my XS1-L02A-QF124-C5 processor card and Ethernet.

The card worked perfect immediately.

This card has a dual core processor but is very small (35 x 60mm).

As with the previous card, all IO are 5V on the 25 pin PC compatible IO port and are from core1 . The ethernet and the yellow led on front is on core0.

The power supply iinput is a min B socket with only the VBUS power signal taken from it. It works from a PC port or from a USB charger.
The download include

-part list

-PCB Gerber files

-schematics

-photos
I can provide the PCB for 5USD.
Images:


ale500
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Post by ale500 »

Great project !

How did you solder the L2 ? Did you send it somewhere ?
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Post by Carpentier »

You should have a microscope set to about 40X magnification unless you have very good vision.
It takes 15 minutes for the preparation.
Spread a lot of 0.25mm solder balls on the chip which was covered with a little quantity of flux (RMA-223 or better NC559). The flux which is rather viscous help the balls to stay in place. The thickness of flux applied is about 0.05 to 0.1mm. If too much flux , the balls will travel when heat will be applied.
under the microscope, with the tip of a very fine plier, move the balls to have 1 ball exactly on each pad of the chip (except the center pad). This require exactly 124 balls. If you have a stencil (I have one now but did not have at the beginning), you can get all the balls placed more rapidly, but it still require a visual check for missing balls, displaced balls etc.
Then , when you have all the balls placed, carefully heat the chip with a hot air gun with minimal airflow (i have done that) or a InfraRed soldering station. when the balls reach melting temperarture, they product a very beautiful solder grid array on the chip.
With the chip prepared like this, take the PCB apply a small amount of flux at the position of the chip, apply a little quantity of solder paste at the big center pad, align the chip with a good precicion (better than the 0.5mm pitch), and reflow the PCB in a reflow hoven, which will solder the pre-balled chip with a good temperature profile( i have done that). It always worked for the 5 samples i have done.
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