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.

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!

New Open Source Hardware KiCAD project board in stock: MOD-OLED-128×64

MOD-OLED-128x64-3

MOD-OLED-128×64 is low cost, low power, high contrast LCD display with UEXT connector which allow to be used with any of our OLinuXino and Arduino boards.

The LCD panel control is done via I2C thus only 4 wires are necessary Vcc 3.3V, GND, SCL and SDA.

The power supply required is only 1 uA in sleep mode, 200 uA in operating mode and 7mA in display ON mode.

View area is 21 x 11 mm.

MOD-OLED-128×64 can be used on Breadboard too. For this purpose 4 pin header is provided which could be soldered on the back of the board.

MOD-OLED-128x64-2

 

 

KiCAD files are on GitHub, Python code to work with any of our OLinuXino Linux board is provided, also code for Arduino.

ESP8266 WIFI chips and modules arrived

ESP

Recently we blogged about the new ultra low cost UART to WIFI modules based on ESP8266 ICs. Today the WIFI modules and sample chips arrived so we can finally test them.

The low cost $5 modules focused the interest of many people. We already have translated datasheet, forum and some people even started write code for Arduino without having these modules at all 🙂

One problem I see is that there are no official schematic with components with values nor reference design. We are going to change this as we already got 3 different modules and the components around ESP8266 are not so many, so we will capture the schematic and make reference PCB layout in the next few days.

Hackaday.io 

ATcommands

Tutorial

Forum

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.

New Product in stock: A10-OLinuXino-LIME-UEXT adapter

Image

A10-OLinuXino-LIME-UEXT is adapter board with Male connector on 0.05″ which can connect to A10-OLinuXino-LIME GPIOs with  0.05″ step ribbon CABLE-40-40-10CM and allow LIME GPIOs to be used with BREADBOARD-1, or with A13-LCD43TS, A13-LCD7TS or A13-LCD10TS.

For the moment A20-LCD15.6 is not supported as LVDS signals got noisy when pass through A10-OLinuXino-LIME-UEXT but we are looking for solution.

UEXT signals can be used only when connected to GPIO1. On the other connectors UEXT signals will be not present.

Why we will not upgrade to Eagle 6

I guess for the same reason we didn’t upgraded to Eagle 5.

We are happy with the 4.16 version which we use and do not miss any of the new features which Eagle 5 and 6 introduce.
Each time new major version is released you have to pay new licensee fee to Cadsoft.
Eagle 4.16 installation is 5 MB and fast, Eagle 5 rise to something like 15 MB if I remember correct and we never saw something more than early bug fixes so we decided to not upgrade and pay again for something we already paid.

Now Eagle 6 is over 40 MB,  let’s see what’s new:

– XML database – we never used such nor need one
– merge schematic / boards we can do it with 4.16 too with a little bit of care
– routing enhancements – we never count on autorouter
– library editor optimisations – so small that not worth mention them
– layout editor add-ons – again insignificant to adjust new payment

what I notice though is that customers who made PCB designs and submit them for production to our PCB prototype service is that Eagle 6 do not generate correct gerbers when there are polygone fills.
I attach example of PCB made with Eagle 6 which do not generate correct polygone fill which leads to shorts on copper plane.

here is example of such board
The general impression is that Eagle 6 is done in a hurry new release to shave the customers with some $$$ which the new Eagle owner obviously need after the purchase.
The bad thing is that one used to be good product before become more buggy and less useful with it’s x10 file size increase and adding useless “features” just to do new release and ask for more money.