Re: RD16HHF1 in the uBITX #ubitx

Eric KE6US
 

Sorry. I got lazy.

http://kd5ssj.com/solderpaste/smt-tools-and-process

Very informative. I haven't tried the beverage warmer he talks about to preheat the board. Good idea, though. I usually just wave the heat gun around a foot or so above the board to warm it up., but the beverage warmer is a more positive step that encourages doing it right.

Some people use a toaster oven for reflow and have developed temperature profiles matching commercial production techniques. That's the right way to do it, and backed up by science, but bench work doesn't always require the same techniques that commercial production requires. I never bought anything from Sony that incorporated dead bug construction, but I'm sure their engineers and techs do initial proof of concept that way.

Fun call on CW. I like it.

Eric KE6US


On 2/21/2018 11:17 AM, K5ESS wrote:

Eric,

Couldn’t find your earlier link to “Cash’s video”.  Could you re-post.

Thanks

Mike

K5ESS

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Eric KE6US
Sent: Wednesday, February 21, 2018 12:07 PM
To: BITX20@groups.io
Subject: Re: [BITX20] RD16HHF1 in the uBITX

 

Looks fine. Mine is from Michael's rated at 360w. It was $20. WalMart might even be cheaper. They're probably all nearly identical. Mine looks like the one you show except for packaging details. BTW, it's super for heat shrink tubing too.

You control the heat with the distance from the piece. I start out about a foot away to get the board warmed up to a point where I don't want to touch it, Keep the end moving. Watch Cash's video that I link to earlier. It's really that easy.

Don't get too close to the part while the solder paste is still grey. There's a point where the solder paste starts getting a little glossy and slick. You can blow the part right off the pads if you get too aggressive. For that matter, I often tape smaller PCBs down as they can scoot around from the air flow too. Then it's magic. The solder turns silver, the part aligns itself right on the pads better than you did, and it's a thing of beauty.

On very tiny parts, say ones with 0.5 pitch pins, you can get solder bridges. Don't worry about them. A light touch with solder wick and a soldering iron and they disappear leaving the part perfectly soldered in place. On many tiny parts with lots of legs, I just lay down a running blob of solder that shorts all the pins together, then wick up the excess. I did about a dozen AD9850s that way. All perfect.

I understand some guys have tremors and other things that would make SMT difficult. It takes a steady hand to place the parts but not nerves of steel. I suspect anyone who can walk from the kitchen to their workbench with a full cup of coffee without spilling any could manage the larger SMTs without difficulty.

SMTs open up a whole new world of kit building and homebrew possibilities. They aren't limiting our abilities at all. We're doing that to ourselves.

Eric KE6US

 

On 2/20/2018 9:21 PM, VE7WQ wrote:

Thank you Eric,

 

What do you think about this heat gun on eBay?

110V 300W Hot Air Gun Hand Hold Mini Heat Gun for Embossing Heat Tool $10.76

https://tinyurl.com/y7vrbfvt

Or should I buy a $20 embossing tool (heat gun) from WalMart or any craft store ?

 

73! George

VE7WQ

 

Tuesday, February 20, 2018, among other things you wrote:

EK> A syringe, a small tweezer to place the parts, solder paste and a $20 

EK> embossing tool (heat gun) from WalMart or any craft store. It makes the 

EK> 20-QFN or any other SMT easy. 

 


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