Another SMT Soldering Technique

Cary showed me how he likes to do surface mount soldering. Mike uses highly activated liquid flux. Cary prefers a gel flux.

Cary showed me 2 YouTube videos that shows the technique. Someone "borrowed" his smt kit.






I went to Fry's and they had some. It worked like a charm. I tacked the part, put some flux down and it all worked as in the videos.

My problem is that the Fry's stuff does not clean up well. So I need better flux gel.

So, I see myself using the gel for multi-pin parts and the liquid flux for the basic caps and resistors.

To practice, I looked on the net and found 2 companies that sell practice boards. One is Topline. They have a board that has 4 tqfp parts. Depending on how many you purchase, it is $10 - $6.75 per part. Practical Components was even more expensive.

So a browsed ebay and digi-key. What I found was smt converter boards on eBay for $1.80 each. Search Google for "smt converter boards tqfp" to find parts. If I looked further, I could have gotten the same board for $1.50. The board is for a single 80-tqfp chip.

Then I looked on ebay for qhips, all too expensive. I looked on digikey. I found a Pic processor for $2.91 in Quantity 10. Part number PIC18F83J11-I/PT-ND.

So minus shipping and tax, $4.41 per practice component. After the fact, you wind up with a working PIC18 if you do it correctly.

I hope that I will not require the 10 for practice, so some people might be getting some practice boards from me.

Once I get this working, I will be very exited. I will have the confidence to build my AT Sprint 3B1 from Steve Weber. And will order his ver 4 in February when it ships. I also have the NUE-PSK digital Modem It does have one TQFP-64 .5mm pitch part. The rest are easier pitch or 1206 components.

Right now I have friends helping me debug issues with a Small Wonder Lab PSJ31 20M rig. I had 2 resisters I swapped, otherwise I placed all components correctly. No cold joints. I have one part that is bad and another is being sent to me.

Crappy passwords

Why is it most sites, especially those that have good reason to require a secure password don't allow symbols?

There are a lovely set of characters on the number keys and a couple of other places. But financial institutions don't allow them. At least not the 3-4 I've dealt with.

I'll admit, I'm not a security hack. I know that some programmers allow certain characters to not be escaped correctly and it causes issues with URLs and SQL. But is it really insecure to allow a backquote or @? Or is it that companies are afraid of the lower common denominator of software engineer will allow known back doors to be opened by use of certain unescaped symbols.

This is a frustration. Or maybe I just need to read more about security to find out in 4-10 characters ( a-Z, A-Z, 0-9) we can create secure passwords. Why can't I type the password I prefer? Why can't I have longer pass phrases like I can with an SSH key?

OK, I'm done bitching for now.

Chumby Guts - cool but can be better

I put my Chumby guts together this week. They are available at the Maker Shed http://www.makershed.com/ProductDetails.asp?ProductCode=MKCH1 for $139. I took advantage of the initial offering of $99.

The chumby is an interesting device. It is a device is like an iTouch or iPhone, but you leave it on all the time and have it flip through each application every 30-60 seconds. Granted there are only about 1300 applications, 200 of which are clocks. But the potential is there.

The chumby has a 320x240 touchscreen, wifi, an accelerometer, 2 usb ports, microphoen and is linux based. Like a facebook app, you can partially host the application.

The 2 issues I have with the chumby is it's wifi and the network interface. The usb wifi card is reallllllllly weak. I even put the wifi card on a usb cable away from the chumby's shielding and it still was horrible. I found an antenna at Halted Electronics that fixed the problem.

• http://www.halted.com/commerce/catalog/product.jsp?product_id=24191
• http://www.halted.com/commerce/catalog/product.jsp?product_id=24192
  

With the antenna, it is working well.

For setting up your wifi password, they don't present a keyboard.
They provide three lines that scroll left and right. One line are the lowercase characters, one upper and the third numbers and symbols. Other than a game console where you cursor through the screen of letters, numbers and characters, I have not seen a worse data entry screen. From playing with the twitter widget, I it can present a keyboard.

So, overall, it is an interesting device that offers folks lots of possibilities for writing network aware widgets.

But for the cost, up the ante on the wifi card and redo the passphrase interface.

Finally used my solder pot.

I am building the Small Wonders psk31 20M transceiver. I wound 4 torroids. t37 and ft50 sized.

There really is a difference in magnet wire coatings. The wire supplied by small wonder did not tin by dipping. But what I picked up at the electronics store did.

I dipped the tips in some flux and then into the solder pot for a few seconds and out came nice shiny tips.

Now, I do not know if they work. There are no diagnostic and setup steps until everything is put together.

CQ CQ NE6RD CQ CQ

12/8/08 at 12:48PST I checked the ULS database and my new callsign showed as approved!!!

NE6RD the NERD.

Built Digital Dial Designed by Steve Weber. KD1JV

I picked this up for 2 reasons. One it is the one surface mount part of the bitx 20M kit sold by Hendtricks QRP Kits and I wanted to have an extra in case I screwed it up when I build my Bitx 20M kit. Second, I am building a series of QRP kits and I need to test the crystals to see how off they are. This kit has a mode where it will do that.

The good news is that this all went together really well. No repairs required.

You can see my solder job on the smt side here:




The parts are all 805 which I consider midsized parts. These are approximately 2mm x 1.25mm. Starter smt projects use 1206 parts which are3.2mm x 1.6mm. I practice with 805 and 603 (1.6mm x .8mm) parts.

When I was first trying kits with 1206 parts I would use thin strips of masking tape so I can use normal soldering techniques. I tried using flux and a tinned tip, but it never really worked for me. I found out why.

As opposed to what radio shack and Fry's will have you believe, there are multiple types of flux. From no clean lightly activated crap to highly activated that requires you wash the board every 10-15 minutes.

My advise, do not bother with the no clean crap! This is the stuff that has people telling you to not use extra flux when you solder.

The highly activated stuff is incredible. Flux is the stuff in solder that makes the solder flow to metal and not the masked area. The highly activated stuff works the best, but it is also highly corrosive to the metal pads and the smt parts. One of the EEs at work showed me this stuff and his technique for doing smt parts. He has to work on boards with 402 parts (1mm x .5mm) and high pitch (dense number of pins) parts, so I take his word as gospel. He has been doing this for years.

He has me take the cap to a large mouth drink bottle, approx 1.5-2 inches, and put a few drops of flux in. You can see this cap in the above picture. Then drop in the number of parts you will solder in 10 minutes. Then take each part, place it on the board, tin the soldering iron tip with enouhg solder and touch the pad and part. The flux fizzes off and the solder gets sucked up and goes where it is supposed to go. For multi-pin parts, I add a drop of flux directly to the placed part.

The painful part is the great stuff only comes in gallon sizes for about $50. Luckily the guy at work has had a gallon for 10 years and gave me enough to last for a long time.

When I clean the board I run water of the board and use a toothbrush to scrub it. To dry it I use paper towel and my heat shrink heat gun.

The soldering iron I use is a Hakko Soldering Station, 936, ESD, With 907 ESD Iron
. It is temperature controlled with a ceramic element that the tip goes over. It recovers fast and heats up fast. The tip I use for surface mount is a 1MM bevel edge tip, a 900M-T-1C. The bevel holds more heat than a pointed tip and has a nice edge. I run the iron between 400-450 degrees. I use .020 thick solder.

You soldering station is a personal preference. But do not cheap out. When soldering, you want one that is adjustable. One where you can easily get tips. One where the tip has a large area of contact with the heating element. One that recovers well should just solder part after part and get good clean shiny solder joints. The Weller WES51
is another good choice from what I've been told. If you can find a used one or have the cash, the Metcal is supposed to be the best. The Hako and the weller are about $90.

I have a 50W quartz halogen desk lamp for light. For seeing things I use both headset and a 10x loop. You can find the headset I own at Amazon, (SE) Magnifier, Headband Lighted
, but a decent 10x loop is not hard to find. Amazon has these as well. The loop is helpful for both inspecting the solder joints and reading the marking on the small parts.

I know there are people that swear by using solder paste. I just have not had the time to try it.

There are those that tin the pads, place the part and reflow the solder. I don't like this one. For one you can't do it on a dense high pin part. You will never get the pins lined up well. Two for small parts like resistors and capacitors, the part is not level on the bard and you are applying a bit of downward pressure on the part. This is where I can see the parts flying out of the tweezers. This also means you are soldering twice. One on the pad and again to reflow the solder.

Lets face one reality here. SMT was meant for robots and industrial soldering machines that use solder paste. What ever we do is going to be a compromise and we will just work with what ever we find comfortable for ourselves. You might prefer solder paste or pre-tinning. This is just how I do it.

I blathered on long enough here.

Summary:

• I built a smt kit and it works.
• Don't cheap out on your soldering iron.
• Do acquire highly activated flux.
• A bright light is required.
• Multiple forms of magnification are required.

Most importantly, have fun!

New Callsign in Progress

I have an application in for NE6RD. When I earned my license I figured I just stick with what the FCC gave me. By the time I earned my extra. I had already made a commitment to KI6QNZ. Logins, memberships, badges and business cards. Now with that my participation with 2 VECs, DSW cards, and using KI6QNZ for last years Maker Faire. And eQSL and Log book of the world.

This is like moving. Worse this is similar to what people who change their name goes through. A call sign change is like a name change. It is a change in identity. You have to let people know in correspondence who you used to be known by.

But just like someone who is willing to deal with all the hassle for love, I am doing it for the true geek factor of what I consider a very cool callsign.

No one else has applied for it, so I just have to wait for the FCC to approve it. Which could take until December 18.

This is supposed to be a slam dunk. The callsign has been available since that last holder upgraded to extra in 2002 and no one else has applied.

But I am not ordering new badges and everything else yet in preparation. I'll wait. I can't wait.

I wanted nerd.com when I got mikey.com back in 1993. This is the next best thing.

Yee Ha!

ARRL offers us support again

I talked with Bob Inderbitzen, ARRL Sales and Marketing Manager, this morning. He has offered support of our effort again. New volunteers and those who have worn out their shirts will get another this year.

Bob has offered books and handouts this year again.

I greatly appreciate the ARRL and Bob's effort to support us in educating people about amateur radio at the Maker Faire.

I hope Bob can make it out again this year. He was a great asset in the booth and a good guy to get to know.