Tags

Post for August 29th, 2014

While I (anxiously) wait for OshPark to mail me my three copies of my first developer revision of the Healthy pH Board, I’m getting tools and techniques together.  I’m also looking into how I can most efficiently solder multiple boards..

The Goal

The goal of this post is to describe the techniques I plan to use to solder the components onto the Healthy pH Shield PCB.

Thanks To Those That Go Before

  • Chris Gammel.  Chris’s Session 1B Contextual Electronics course helped me make a monumental leap forward in my soldering skills.  The other students were also amazing in their abilities and sharing what they know.  I love being the person who has the most to learn in a class and being able to keep going through the firehose of learning!
  • OshPark for making it possible to inexpensively, easily, and quickly (but of course not quick enough 🙂 ) to fabricate PCBs!
  • OshStencils for providing a service to create inexpensive stencils.
  • Curious Inventor and EEVBlog for creating some great videos on soldering techniques.

Previous Efforts

We did a lot of soldering of SMD components onto a PCB during Session 1B of Contextual Electronics.  The biggest challenge was soldering the MCP3901 ADC 20-SSOP.  Wow – this is one small part for my soldering skill set!  After much frustration with my soldering iron, I ended up getting an AOYUE 968A+.  While I appreciate the smoke absorber, the hot air soldering iron.  How did I live without it?  

Yet, I am proud of the soldering job I did with the soldering iron and solder:

in order to use an MCP3901 on a breadboard, I decided to order an SSOP to DIP adapter from Sparkfun. I used the soldering method described in this Curious Inventor Surface Mount Soldering 101 video.  I found:

  • holding the part over the pins
  • applying the right amount of solder.  To conquer this, I used a lot of flux on the pads and then just used the solder from tinning the tip.  I found adding any more solder created clumps that took me a LONG time to clean up with a solder wick.
to be the biggest challenges.

A fellow student in my Contextual Electronics course had occasionally used self closing tweezers for holding parts in place.  What a great idea!  I found using self closing tweezers to be a tremendous tool for holding the MCP3901 in place on the SSOP to DIP adapter.

I got these on eBay – although I would advise getting a smaller size.

Happily, the soldering worked and I can now prototype circuits that include the MCP3901.  A definite YIPPEE! moment.

Soldering the Healthy pH Shield

Given my experience and current skill set I’m exploring a few different ways to solder the components onto the Healthy pH Shield.  They share a common point in that I decided the easiest method for me is to use reflow.   This way, my overly shaky hands won’t get as much in the way.

Pieco Paste Press + AOYUE Hot Air Soldering Iron

The biggest challenge I have had with using the hot air soldering iron is getting the right amount of solder onto the teeny-weeny pad.  I started looking for inexpensive methods of solder paste dispensing that was better than my fat thumb pressing on a syringe.  I ended up buy a Pieco Paste Press on Tindie.  I broke my own rule when buying.  I like to ask a support question and see what response I got.  I wrote both a message on Tindie to Pieco as well as tweeted a question to their twitter account.  I did not get a response on either one.  I was surprised.  A big reason I like to buy from “the small guys” is because I have this perhaps unfounded belief they are passionate not only about their product but also their customer.  Having done support for my own company, I can imagine the person or few people to be “really busy” but in my experience I always found time to at least let the person know I don’t have time…

I also bought 10CC of ChipQuik solder paste from digikey.com.

Awhile back I had bought several soldering practice boards from ebay.

Practice Soldering PCB

I tried the Pieco paste press with a 23GA tip.  The solder came out easy enough.  However, I had trouble getting a straight line on a pad like is shown on the Pieco video.  After putting on lots of flux, I tried to “carefully” put the solder paste on the pads.  Hopefully, I will get better over time.  For now,  the best I could do was spread the past along the pads and pins then turn the hot air reflow iron on….

PCB With Solder

I circled the two areas where I used solder wick to pick up the extra solder gluing the pins together.

I thought the solder paste worked well – at least better than the last I got.  More experience and finding out what others use will evolve my choice.  I’ll keep using the Pieco paste press when I do this type of soldering in the future.  Right now I am not overly wowed by the outcome.  However, the lack of precision could very well be on my lack of knowledge and skill in how to best use the paste press.

Stencil + Hot Air Soldering

Once I (geez – it’s hard to wait!) get the dev boards from OshPark, I’m very excited to try out the stencil I just received from Osh Stencils.

 

OshStencil

I’ll be using the technique Dave showed in his EEVblog video #415 – SMD Stencil Reflow Soldering Tutorial.

Another way to get to a stencil….Thanks to a posting from the Amped Hour subreddit, I read this blog post on DIY Stencil.  I hope to try this technique in the future!

Stencil + Oven Reflow

Our local hacker space – Metrix Create Space – has a reflow oven I can lease by the half hour.  If I’m not too lazy, I plan to find my way there and give oven reflow a twirl…

 

So much to learn…

Thank you very much for reading this far.  Please find many things to smile about.

Advertisements