Week 4
Assignment 5
Electronics Production:

Electronics Production:

Objective:

1. Group assignment:

This week is having the following Objectives for the Group-

  1. Characterize the design rules for your PCB production process: document feeds, speeds, plunge rate, depth of cut (traces and outline) and tooling.
  2. document your work (in a group or individually)
Details here.

2. Individual assignment:

Make an in-circuit programmer by milling and stuffing the PCB, test it, then optionally try other PCB fabrication process.

Learning Outcomes:

Described the process of milling, stuffing, de-bugging and programming
Demonstrate correct workflows and identify areas for improvement if required

Checklist:

Linked to the group assignment page ✔

Documented how you made (mill, stuff, solder) the board ✔

Documented that your board is functional ✔

Explained any problems and how you fixed them ✔

Included a ‘hero shot’ of your board ✔

Opening Quotes:

Electronics is clearly the winner of the day.--- John Ford
When I was a teenager in the late 30's and early 40's, electronics wasn't a word. You were interested in radio if you were interested in electronics. --- Ken Olsen
My hardcover sales are 17% down in books but up 400% in electronics. --- Lisa See
By the end of this decade, computers will disappear as distinct physical objects, with displays built in our eyeglasses, and electronics woven in our clothing, providing full-immersion visual virtual reality.--- Ray Kurzweil
Each of us is now electronically connected to the globe, and yet we feel utterly alone.---Dan Brown

Electronics Production:

The task of this week included assignments to be done in group and individually. We have to mill PCB plates, solder the components over it. For two weeks, we have been only working on the laptops. From last week, we have been making our hands dirty on the machines and learning to fabricate with the CNC machines.

Two of us already had experience of Milling and Soldering. They took lead and we divided the tasks amonst us. I have drafted the Group Assignment by taking the Snapshots, Screenshots and documenting the process. The details of the Group assignment could be found here.

Individual Assignment:

In this week, we had to individually mill, stuff, program the Fab ISP PCB plate.

A. PCB Milling:

PCB milling is the process of removing areas of copper from a sheet of printed circuit board material to recreate the pads, signal traces and structures according to patterns from a digital circuit board plan known as a layout file.

PCB milling is typically a non-chemical process and as such it can be completed in a typical office or lab environment without exposure to hazardous chemicals. High quality circuit boards can be produced using either process. In the case of PCB milling, the quality of a circuit board is chiefly determined by the system's true, or weighted, milling accuracy and control as well as the condition (sharpness, temper) of the milling bits and their respective feed/rotational speeds.(wikipedia)

A. Introduction to PCB Milling machine at FabLab-0 – Vigyan Ashram, Pabal:



(Source: https://www.dgshape.com/en/srm-20/)

Introduction to Machine

After the Global review, next day we were introduced to the milling machine.

We have SRM-20 Milling Machine by DG Shape (Roland) in our FabLab. On Thursday, the 18th Fab. 2021 we were introduced to this machine by our Local Instructor (Mr. Suhas Labade). During the introduction, we were told about the DO's and DON'T's of the machine operation which included the Cleanliness of the machine and work area, ensuring safe and proper electrical connections. Door of the machine should be always closed while operating and giving commands or else it will not operate due to magnetic switch in the door for enhanced safety feature.




B. Preparing the SRM-20 machine for Milling:

Very first thing to start with the machine is to clean it and ensure proper electrical connections.

We have used the FR-1 material for PCB milling.

Our SRM-20 milling machine has used two layers of 12 mm acrylic sheets as sacrificial layers. This is because the head of the machine cannot reach the depth of the bed.

Steps followed by us for the operation of the Milling machine are as follows:

15. The process of setting / mounting the drill bit is as follows:

C. CAM Operation (Configuring / Generating Tool Path using MODS):

The process of CAM operation or Configuring / Generating Tool path is as follows:

D. PCB Milling (Trace Cutting and Outline Cutting):

I tried to mill another PCB but due to uneven surfac and improper levelling of the overlay and bed area, it had burring and superficial trace cut. I didnt tried double pass as it already had the burring.

E. Learnings:

F. Caution:

B. PCB Soldering:

Soldering is an especially common requirement for jobs involving circuit building, PCB assembly and electronic prototyping. For this assignment, we will be soldering the following components of FAB ISP PCB plate as given in the Brian’s Fab Academy page

Tools required for the fabrication of Fab ISP by Brian are:
Appropriate tools are always necessary to make a clean soldering. Also it will make our life easier.

Being new to the Electronics, I first tried to understand the components by asking about what is called what? how does it looks? what it does? how to differentiate?

The components used in the SMD PCB fabrication are altogether different than those used in the Throughhole PCB fabrication.

I also tried to understand about the polarity of the Diodes, LED's and the Integrated Circuits (IC's)

I came to know that :

  • Zener diodes are always connected in reverse position as they work in breakdown region.
  • There is a small dot on the IC's which needs to be connected to the first pin.
  • LED's have markings on them to convey the negative terminal.

    • This was first time of soldering in life. I first tried soldering on the old Through hole PCB plates by desoldering the attached components by using desoldering hot air gun. Then I soldered few components again.

    Then, I desoldered the components on SMD PCB plates and soldered them again. My hands were shaking and water rolling out of eyes due to focus while soldering the tiny components.

    After this net practice, I then collected all the required components and started soldering. I approached by first soldering the small components and then atlast soldering the IC and Connector pins. This will allow you sapce for working. If the connector pins and IC are soldered first, it will be difficult to solder the smaller components.

    Some Issues that I faced were:

  • Components used to slip out of the tweezer due to more pressure or improper handling. Even they would not remain in place.
  • Cold Solders: To avoid more soldering on the pins, I quickly removed the soldering gun and used very little solder wire. So, the pins were not connected and not soldered properly.
  • Sometimes, my solder wire used to stick to the pins as I removed the soldering iron first and then tried to pull the solder wire.
  • Due to more solder wire, few pins/joints on the PCB plate got connected with each other.
  • I forgot to check the polarity and continuity of the diodes and LED's which led me to do the desoldering again.

    • My approach to Soldering after observing my experienced colleague changed.

    I, now-

  • first applied flux liquid to the PCB plate
  • applied little solder to the PCB plate where I had to solder the component.
  • connected one pin, fixed its position at a time on the PCB plate and then diagonally soldered and then connected other pins.


    • Hero Shots of my Board

    PCB Programming:

    I am having Windows OS on my Laptop. So, I had to install the required programs and softwares to Program the fabricated Fab ISP. It is easy to do on the Linux OS by command line.

    The process for Using the GNU AVR toolchain can be found here.Building the Fab Tiny ISP

    The process for Using the GNU AVR toolchain on Windows 10 can be found here.

    The Screenshots of the AVR Dude Toolchain, AVR GNU, Make and Adafruit drivers installation process on my Laptop are given below.


    Downloading Make


    Downloading avrdude


    Defining Path for installing the software


    Make Setup Done


    Make succesfully installed


    Defined the Location of make setup


    Provided the Admin permission for making changes


    Changed the path


    New Path is generated



    Changed the File Name


    Deleted _x86 from the File Name


    Stated gitbash


    avr GNU Toolchain processed


    USB tiny programmer

    The .hex file could be found here.


    in HEX file change to USB tiny



    Firmware download


    Configure the Firware






    The various commands used by me in Git Bash for programming the PCB plate (Fab ISP) are:

  • make
  • make flash
  • make fuses
  • make rstdisbl

  • The PCB was detected by the Laptop and LED would glow BUT ERROR occured when I gave the command to make flash.
  • It prompted a warning suggesting me to check the connections.
  • I then realized the problem of COLD SOLDER where there are gaps in the circuit and the pins are not properly soldered. The IC pins were loose and not connected to the PCB plate.
  • Even for the first time, it suggested to install adafruit drivers in my Laptop.
  • I sorted the issue by Soldering properly again and resumed the process


    • used make command


    used make flash command


    used make fuses command


    used make rstdisbl command


    configuration process ongoing and completed the setup


    I prepared two ATtiny45 programmers. So, applied the same process to make it programmable.


    used make fuses command

    After the installation of AVR Dude, GNU, Make and adafruit drivers, I then used Git Bash for programming the PCB plate (FAB ISP) fabricated by me earlier. The Screenshots of this process are given below.

    Issues during programming the Fab ISP faced by me:

  • The PCB was detected by the Laptop and LED would glow BUT ERROR occured when I gave the command to make flash.
  • It prompted a warning suggesting me to check the connections.
  • I then realized the problem of COLD SOLDER where there are gaps in the circuit and the pins are not properly soldered. The IC pins were loose and not connected to the PCB plate.
  • Even for the first time, it suggested to install adafruit drivers in my Laptop.

    • I then downloaded the FFMPEG for Windows to Compress the size and trim the length of the Video. I used the commands given in CAD Design Week here.

    Video Stream of the LED's Flashing while programming the Fab ISP:

    Downloads:

    The Original Design Files of PCB Trace Cut of Brian FABISP, Test as well as the .HEX file can be downloaded from here.