controllers; program in C

Hello, all,

I have a board I manufacture. I have a pick and place, and have the SMT reflow process working like a charm. But, it has a LOT of through-hole connectors, and I am dip soldering these with a solder pot. I first mask a few holes I don't want filled with Kapton tape, then brush liquid flux on the board, and insert the

40 connectors and power FETs, and dip it into the solder pot. There are a few problems, but the big one is solder icicles that form on certain pins. I've tried a bunch of different remedies, none have helped much, yet. I am using SAC305 bar solder. I've gone from 250 up to 290 C on the solder pot, I've tried holding the board in the pot for 5 up to 15 seconds, I've tried lifting it straight up and tilting it to break the solder surface tension, and even shaking the board right after lifting it. But, I still get the icicles and bridges, that I then have to go and rework by hand.

Anybody have ideas on how to fix that?

Thanks,

Jon

(Oh crap, my news reader attached this to a different thread, sorry!)

Hello, all,

I have a board I manufacture. I have a pick and place, and have the SMT reflow process working like a charm. But, it has a LOT of through-hole connectors, and I am dip soldering these with a solder pot. I first mask a few holes I don't want filled with Kapton tape, then brush liquid flux on the board, and insert the

40 connectors and power FETs, and dip it into the solder pot. There are a few problems, but the big one is solder icicles that form on certain pins. I've tried a bunch of different remedies, none have helped much, yet. I am using SAC305 bar solder. I've gone from 250 up to 290 C on the solder pot, I've tried holding the board in the pot for 5 up to 15 seconds, I've tried lifting it straight up and tilting it to break the solder surface tension, and even shaking the board right after lifting it. But, I still get the icicles and bridges, that I then have to go and rework by hand.

Anybody have ideas on how to fix that?

Thanks,

Jon

Jon, maybe this should be a separate thread... it doesn't really connect with uC's for a battery charger.

Hand soldering is not an option? (It would save the masking time.

George

Jon - no real ideas, just the random approach: different flux, baking/drying flux prior to soldering, different solder (what's SAC305?). If you can use a leaded solder, plain 60/40 is usually a pleasure.

Hul

J> (Oh crap, my news reader attached this to a different thread, sorry!)

Some years ago I would have said "Yes, use a Pic".

These days, I'd suggest going with an Arduino. C is the standard development language, the development system is free and is available on multiple platforms, and there are many libraries available which "abstract away" the hardware details so you don't need to poke specific registers as much as with a PIC.

One example: the Arduino Pro Mini board. 0.7x1.3" board, has an onboard power regulator, 14 digital pins and 8 that are analog-capable, on-board bootloader (you need a serial-port-to-TTL adapter or USB-to-TTL cable, both cheaply available). You can direct-wire to the pads, or solder in some pin-headers and then plug it into a pin-socket array on your main board.

$10 in onesies from SparkFun, and I've seen clones of it available from vendors in China for about $4.50 each including slow-post delivery.

I think you'll find that it beats out the price-performance ratio of a good C-capable PIC, once you factor in the need to build some sort of board for the PIC with a bunch of components that are already on the Pro Mini.

Den tirsdag den 10. februar 2015 kl. 23.22.59 UTC+1 skrev Dave Platt:

Much more bang for the buck is the numerous ARM cortex boards, like the stm32 discovery, ~10$ including a real debugger, 10x the speed, 10x the memory, 32bit, many more peripherals

-Lasse

contamination / oxidation of the solder?

For a battery charger? You are joking. I have a i7 for a home automation process, do you think I need to upgrade it? Plus the Arduino's have much more support and documentation available with much of it written for newbies.

You can get ARM Cortex M0 parts for less than 90 cents each in 1ea quantities. The debugger (ST-Link is good) can be had for $30 (or maybe less), and professional-quality development tools are open source and free.

That's not to knock the Arduino boards -- but it's hard not to like the Cortex parts.

--

Tim Wescott 
Wescott Design Services 
http://www.wescottdesign.com

Yep, and it's an open market. There are several manufacturers to choose from. Need more performance? ...move up to an M4 or M7.

M0s are pretty low power, as well.

Your other points are valid.

Yes, you can get an M0 in a pdip, although DigiKey only lists one part:

--
www.wescottdesign.com

SAC305 is Tin (Sn) + 3% silver (Ag) + 0.5% copper (Cu). No, I can't use leaded solder, I sell these boards all over the world.

The flux is working well, I get gorgeous looking joints, just too much solder hangs onto the pins from certain connectors.

Thanks,

Jon

Jon - what are the make & model of the connectors causing trouble? I'd like to keep that info for future avoidance.

Hul

J> > Jon - no real ideas, just the random approach: different flux,

On a sunny day (Tue, 10 Feb 2015 13:06:16 -0800 (PST)) it happened snipped-for-privacy@outlook.com wrote in :

The small PICs (16F 18F) are much better programmed in asm. You can build a programmer from junk (I did), in Linux gpasm (part of gputils) is free, Linux is free, and I have written huge programs with those tools that work. Even wrote the PIC programmer... So, it up to you, add some transistors and maybe an LM317 and you can charge anything, powered from a wallwart.

Start maybe by switching on - and off a LED with a PIC. For Raspi:

For PC:

On a sunny day (Tue, 10 Feb 2015 14:22:43 -0800) it happened snipped-for-privacy@coop.radagast.org (Dave Platt) wrote in :

Then I would go for te hRaspberry Pi, as it has nice HDMI and analog video out, audio out, signal generator, and is also C, and runs Linux. Huge user base. And I wrote a PIC programmer for it.

Fifteen years ago, I might have said "PIC" if you are desperate to use a DIP package. Other than that, I would only use PICs as caltrops.

The Arduino, as you recommend below, is definitely the way to go for a newbie in microcontroller development (unless you need enough processing power to move up to a Raspberry Pi).

Forget about getting good results by hand dipping and get a small fountain type selective soldering machine. (Wave machines work well too but tend to be large and expensive.) You need the flow of a fountain or wave to get icicle free soldering. Small fountain soldering machines intended for rework can be had for under $2k, for example the Hakko-485-485-V12-Mini-Wave-Selective-Solder-Fountain-Rework-Machine. I am not recommending this particular machine, it is just the first one I found, there are others which may better suit your needs. Spend some time reading up on the process before investing.

Well I'll be... I learnt something today and there are a few of them. Still can't figure out what I's use a 32-bit processor, no A/D in an 8-pin pdip for. Actually not true - If I was fully geared up for cortex it would be a logical choice. For someone who used to K-map functions it still

*seems* a waste..

Thanks!