TuxCon-Kitty the OSHW TuxCon 2017 conference badge soldering kit is in the web shop

TuxCon-Kitty

TuxCon 2017 conference was 3-4 of June in Plovdiv. Specially for the conference we made soldering kit badge, designed with KiCad and programmable with Arduino IDE.

TUXCON-KITTY-1

Here is how it looks assembled:

1a

2a

The project is hosted at GitHub. It’s good way to learn how to assembly SMT components and how to install, setup and program with Arduino IDE.

Do not hesitate to make pull request for your Arduino sketch if you manage to compose your own music with this board 🙂

 

We are back! Tg for PCB quiz answer

pcb-fabrication

Tg is the glass transition temperature of the PCB material and very important parameter.

At this temperature the raw PCB material changes from stiff glass-like material to a elastic and bendable plastic-like material.

The biggest problems in the PCBs during the assembly is the Z-axes thermal expansion as above Tg temperature PCB expands rapidly and if kept long time about Tg temperature the small PCB vias may/will crack internally.

The most evil part is that when the PCB cool off the vias will shrink and may still give unreliable contact like touching together two copper wires, but later with temperature changes, vibration moisture these internal cracks in the vias can cause lost of electrical connections on random basis.

Tg 135 was commonly used and good enough for the old SnPb technology.

Since 2006 the new Lead Free technology require higher soldering temperatures and Tg 135 is not good choice.

PCBs assembled by ROHS lead free technology should be done with material with Tg 170 to be reliable. Especially this is valid for multilayer PCBs with small vias less 0.4 mm.

A64-OLinuXino update, the Rev.B design will be possible to produce in industrial grade -40+85C, dual voltage eMMC 3.3/1.8V

А64-1cut

A64-OLinuXino first prototypes were made in March and lot of people wonder why we do not release for mass production this board yet 🙂 so we got lot of e-mails and I see there is need for blog post with update.

Here is the recap from the first prototypes:

  • RAM memory works at amazing 667Mhz clock much more than A20 and other boards and the board works stabile under stress tests for many hours
  • eMMC works fine, we didn’t test NAND Flash due to the missing Linux support probabbly this will stay just as option and we will assembly the boards with eMMC which is faster, better and in industrial temperature
  • Linux Kernel is 3.10.65 and works fine, we managed to run all peripherials
  • Audio In and Out is working
  • HDMI is working
  • USB host is working
  • USB-OTG is working
  • WiFi+BT is working
  • MIPI interface – no display which to use to test, any ideas?
  • HSIC interface – don’t know how to test, any ideas?
  • LiPo charger and step up works
  • LCD works
  • Ethernet Gigabit interface works just in master mode

While we worked on this board we found new PHY from Microchip which can be ordered in industrial temperature, we tested it with A20 and it works fine (we already have LIME2 version with it which is on prototype), so we decided to re-design the Ethernet part of A64-OLinuXino with it, this will allow us to produce A64-OLinuXino in industrial temperature grade -40+85C.

Another major upgrade for Rev.B is around eMMC interface, we re-designed it as per your feedback to be possible to work on programmable 3.3V and 1.8V thus to allow faster transfers.

Rev.B is routed at 90% we need 1 more week to complete it and run new prototypes. If everything goes smoothly we will be ready by end of the month.

 

Quiz Answer – PCB Layers stackup

PCB-STACK

On the picture above you see 4 layer PCB. The layer stckup is very important if your board will have controlled impedance, i.e. if you route high speed signals.

For most of our designs we use this standard stackup:

  • TOP copper signal layer 35 um finished copper thickness.
  • P2116 prepreg which have 100 um thickness.
  • internal copper GND plane with 35 um copper thickness.
  • Core 1.2 mm
  • internal copper GND plane with 35 um copper thickness.
  • P2116 prepreg which have 100 um thickness.
  • BOTTOM copper signal layer 35 um finished copper thickness.

When add all above we get total PCB thickness = 0.035+0.1+0.035+1.2+0.035+0.1+0.035 = 1.54 mm +-10%

Why we use this stackup? Because with it, the traces with 5 mils width have about 50 ohm characteristic impedance and 5 mils is convenient for high speed signal routing.

 

Our Help Day for September is this Saturday 26th of September in our training building

Help Support Advice Assistance and Guidance on a signpost

Our next Help Day is this Saturday 26/09 at 11.00 o’clock in our training building.

If you need help with your project, or you don’t know how to use some of our boards you can come this Saturday at our Help day.

We got a number of requests to make KiCAD workshop in Plovdiv like the one we did in Sofia at Hack Conf this weekend, so if you want to get familiar with KiCAD you can come on the Help day with your laptop with KiCad pre-installed and to learn how to use it 🙂

We use KiCAD extensively this year and already got more than 20 boards designed with it, so we got some experience we can share.

We will make KiCAD workshop on HackConf 2015, 19-20 of September in NDK, Sofia

hackconf

We have been invited by Hack Conf 2015 organizers to make workshop and will take this opportunity to make small workshop about the Open Source PCB CAD program KiCAD.

The workshop will get you introduced to KiCAD, the flow of work, component library creation, schematic capture, PCB layout. At the end of the work shop you will be able to make your first small PCB with KiCAD and to prepare files for manufacturing.

Bring your computer with you and download and install KiCAD before you come. KiCAD can be download from http://kicad-pcb.org/

Looking forward to see you there!

myNetPCB – simple Open Source Schematic drawing program – Made in Bulgaria

myNETPCB

I got interesting request yesterday – we keep on our web long list with different CAD tools for PCB schematic design and layout.

Sergey Iliev asked me to add to the list the CAD program he works on last 4 years. The project is open source written in Java and hosted at SourceForge (yes this site is still live and kicking 🙂 )

He said he is working now on the PCB layout accompany program.

What impress me is that the package is only 600K Zip file.