Solder paste/flux manual syringe applicator

[zapta]

But is this the speed they can go?, say, for dispensing, it's ok, but if you pull it back, I would guess one would increase the speed just a tad, or is that no point?
Like, press for dispense, leave the button, and it pull back a tad fast, and press again, it push where it was, and a bit more for leaving the solder? (kinda like simulating the air based ones?)

I couldn't manage to generate distinct individual drops by push/pull cycles as done with air pressure based devices (I presume, not experience with those). I think the main problem is the free play in the system and the limited speed of the geared motor.

However, I got good results  (second picture here https://www.eevblog.com/forum/reviews/solder-pasteflux-manual-syringe-applicator/msg747923/#msg747923 ) by creating a very very slow rate of feed and hitting the pads at a fixed rate, leaving the needle longer on larger pads. The motorized syringe and the speed control potentiometer enable a much better control of the flow, especially at very low rates, than pressing by hand.

[mike_58]

Seems like the servos are strong enough for this usage anyway?

Seams to me servos could be used - metal gear -360 rotation - could be controlled as stepper ...
Metal Gear Continuous Rotation Tower Pro Servo
Product Code : RB-Nex-40 [/b]  by Nexus Robot RB-Nex-40
Metal Gear Continuous Rotation Tower Pro Servo
The 360 Degree Rotation Metal Gear Servo Motor is a double bearing, coreless, metal gear, standard
torque 360 degree rotation servo motor. It is suitable for mobile robot driven motor. Also, it can be use
for wheeled and perfect for medium-sized electric airplanes, helicopter or mini mobile robot kit, etc.
This servo motor comes with a number of various servo horns and arms with mounting hardware.
Specifications
• Working Voltage: 3-7.2V
• Working current: 100m A
• Working torque: 13kg/cm
• Average speed: 53-62 rpm
• Rotation range: 0- 360 degree
• Working Temperature: -30 ~+60 ? ?
• Size: 41.7x19.7x42.9mm
• Weight: 55g
http://www.robotshop.com/en/metal-gear-continuous-rotation-tower-pro-servo.html
http://www.robotshop.com/en/catalogsearch/result/?q=Metal+Gear+Continuous+Rotation&order=stats_sales_order_count&dir=desc

GS-5515MG 15kg High Torque Throttle Steering Servo Metal Gears
http://www.ebay.com/itm/New-GS-5515MG-15kg-High-Torque-Throttle-Steering-Servo-Metal-Gears-Free-Shipping/251913518476?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D33601%26meid%3D30c31434633a4c628bf3edfb50b1a840%26pid%3D100005%26rk%3D1%26rkt%3D6%26sd%3D251913518748

[zapta]

If you are using servos, Servo City has a variety of servo shaft couplers.

https://www.servocity.com/html/servo_shafts___couplers.html

[neslekkim]

Seems like the servos are strong enough for this usage anyway?

Seams to me servos could be used - metal gear -360 rotation - could be controlled as stepper ...

Crap, I meant stepper of course, not servo

[mike_58]

scale shows - kg

Shows something, but no way can it be read in the photo or video, hence my (light hearted) comment. Worth bearing in mind a lot of stuff isn't obvious to other folks that aren't there.

For some reason notes on video do not show up if using mobile phone..,
Try your computer or You Tube and you should be able to see notes of values added to video..

[PlainName]

Desktop browser. But loaded with privacy options, so possibly non-video overlays from a third-party site wouldn't show. Well, obviously your notes didn't

[Later...]
Nope, disabled all that stuff and still no overlays. Oh well.

[zapta]

I played today with syringes (motorized and manual) and solder paste and I think that I found the recipe for successful dispensing of solder paste.

The problem I had was that the solder paste didn't stick well to the board, even when using for example fresh from the factory Senju paste. In addition, filling the syringe and removing the air bubbles was a pain.

It seems that applying the paste using a syringe requires a more fluid or thin paste. I mixed a little bit of paste with Kester 981 until it became softer and sticker (try to apply to a PCB with a toothpick, make sure the drop sticks to the PCB) and then filled the syringe (thin paste, it flow well, air bubble stay at the top) and it worked like a charm (I used a very thin needle, maybe #26 or thinner, not sure) and every drop stuck to the board.

This worked well even when applying from the syringe manually, without the motorized dispenser.  The motorized syringe makes it easier to control the flow, especially at a very low rate, but using a regular syringe should be doable.

One paste that doesn't require dilution with flux is QuikChip T5. All the other pastes I used were T3 so am not sure if all the T5 are thiner and sticker out of the box.

[PlainName]

Interesting. Thanks for the info, and the testing

Presumably there is no problem with having too much flux on the board?

[KL27x]

I don't like being the voice of negativity, but that's where I am. I think hand pasting is a waste of time except in very specific circumstances of very dense component arrangement and/or boards with no soldermask.

Sloppy hand pasting can leave solder balls and potential bridges. Oven reflowing leaves dried out connections that can be more deceptive to inspect. And hand pasting doesn't really save any time in most cases. Rather than pasting each pad, and then placing, you can solder each pad while placing. The biggest added step in hand soldering is the prefluxing of the pads, which takes much less effort and attention than hand pasting. Depending on what tip you use, you may have to flip the board, here or there. But that's quite often a small price to pay for having zero chance of smearing parts, no need to bake the board, and to spend very little time inspecting and reworking boards for tombstoned caps and bridged or crooked IC's. Not to mention having your dispenser tip start going wonky and having to clean it off to get it to work, again, because the slightest crud changes the way the paste dispenses and sticks. This is doubly the case when doing panels/batches of the same board, because you can run through the same part or three on all your boards, then setup all your boards for the next couple of parts without having a minefield of solder paste and pasted parts to pay attention to.

I have the paste. I have the oven. I'll use that stuff with stencils, on occasion. That's about it. I have tried hand pasting, and even when it works, great, it's usually not worth the time/effort.

[zapta]

Interesting. Thanks for the info, and the testing

Presumably there is no problem with having too much flux on the board?

I would think that as long as the paste is not to watery and stays on the pad it's good. There is no such thing as too much flux

(I am not an expert, if there is an expert here please chime in)

[zapta]

Sloppy hand pasting can leave solder balls and potential bridges.

I always inspect and rework if needed, even when using stencils.

[KL27x]

This is why even stencils don't save time on many board layouts. When hand soldering SMD, you see a shiny joint that covers the pad, and you're done inspecting. But at least with a stencil you can use dry, hard paste that doesn't run and create solder balls. Without the PNP machine, paste solder is not quite useless. But it's pretty close. It saves a little time in one way, but it creates a lot of extra work and reduces overall reliability, IMO. Inspecting every single component after baking is tedious and can be mistake-prone.

I wish I could get more use out of my reflow oven and solder paste and stencils. But they rarely save me either time or effort, and the results are certainly not an improvement.

In a way, I feel like I was duped into believing that a reflow oven was somehow going to save me time and effort, because other people are doing it. And because of threads like this. And let's face it, most of us "gear heads." For me, I could have saved the money if I hadn't had to just see for myself. I've baked maybe 30-40 boards, since I got it, and caused myself more work, if anything. And I've hand soldered several hundred faster and easier, and with a much lower (nearly nonexistent) error rate.

[packetbob]

While everyone has different preferences and experiences, I find that using a solder paste dispenser and a reflow oven is way better than trying to hand solder SMD parts. I have not ever bothered with stencils as my boards are typically one offs and I can paste one up (using a dispenser) much quicker than setting up and aligning a stencil.

Though I agree with hand soldering you do see the result immediately. I have never been able to do a decent job (mind you I have shaky hands and slowly worsening eye sight) with it.

Unfortunately the air powered dispensers need compressed air but if you manage to get one setup I would think you will see the value in the reflow oven...

Or not..
YMMV...

[KL27x]

I would use stencil and reflow for boards with lots of large, multi pin high thermal capacity connectors, maybe.

I have never been able to do a decent job

Believe it or not, there's probably a way to get great results even with shaky hands and poor eyesight. If you can place an IC on solder-pasted pads, you can hand-solder any SMD component, easily. But to do it efficiently, you do need to be pretty competent with your left-hand.

The one major advantage of solder pasting is you use only your dominant hand to do 99% of the work. This is also why it's often a waste of time (IMO) for people that can proficiently use both hands and can easily hand-solder.

[PlainName]

Gosh, what variation in techniques. And yet... it seems to be hand solder or paste and oven. Does no-one (else) dob some paste down and then use an iron as they place parts? Not oven involved, no stencil involved, just using paste instead of solder wire.

For that kind of application these applicators seem ideal, although I guess stencils would work too (but who wants to pay for, or make, or even wait for, a stencil for a one-off board).

[zapta]

For that kind of application these applicators seem ideal, although I guess stencils would work too (but who wants to pay for, or make, or even wait for, a stencil for a one-off board).

I am a hobbyist so whatever I like at the moment is ideal for me

[packetbob]

Gosh, what variation in techniques. And yet... it seems to be hand solder or paste and oven. Does no-one (else) dob some paste down and then use an iron as they place parts? Not oven involved, no stencil involved, just using paste instead of solder wire.

For that kind of application these applicators seem ideal, although I guess stencils would work too (but who wants to pay for, or make, or even wait for, a stencil for a one-off board).

Actually I have used this method and probably had better luck than by using regular solder..
There are many ways to get the job done and whatever works is the best way...

The earlier poster mentioned they felt duped in a way by getting a reflow oven (I'm sure this sounds worse than he may have really felt) and trying stencils. I hope he has tried a paste dispenser before giving up on the reflow oven (Again this may not be his intention, just my interpretation of his note).

[zapta]

The earlier poster mentioned they felt duped in a way by getting a reflow oven (I'm sure this sounds worse than he may have really felt) and trying stencils. I hope he has tried a paste dispenser before giving up on the reflow oven (Again this may not be his intention, just my interpretation of his note).

I have had very good results with stencils and reflow oven but got tired of cleaning the stencil, squeegee and jig.

[KL27x]

Does no-one (else) dob some paste down and then use an iron as they place parts? Not oven involved, no stencil involved, just using paste instead of solder wire.

Have definitely tried this. It was fun and easy, but unless I'm super meticulous, it leaves unflowed solder paste under parts and behind the pins! And instead of applying solder paste, you can just apply flux, alone. Then touch the bare iron to the pins. Unlike solder paste, you can't "miss" or smudge or get unflowed paste anywhere with the flux and iron tip. There are soldering iron tips that are made to hold a big reservoir of solder, so applying paste solder isn't necessary, at all. All you have to do is pick up solder on the tip of the iron as you pick up the next part (or every several parts, as the case may be). Heating the joint with the iron and applying the solder wire directly to the joint may be "textbook," but that textbook was written in the 80's for use with through hole, oxidized parts, and apparently drag-soldering is plain wrong by these rules. When I do SMD soldering, "solder wire" isn't even part of the equation. I could just as well dip the tip into a pot of molten solder or touch a bit of huge 0.062" wire, or I could use the method which I happen to be currently using, which is to pick up solder from my combined cut tape part holder + "solder pickup and tip cleaning station," where I solder lengths of solder wire over a surface of bare FR-4, which collects excess flux and also cleans/rewets the tip at a touch. (If I need to remove excess solder from the tip for a drag-solder operation, I can touch the tip to the fluxy surface to rewet it and jab the iron in the air to fling the excess solder off onto this board, where I can pick up the solder balls, later). Pick up part, pick up more solder as necessary, as soon as part is lined up, jab, jab, jab, done. Same thing as placing paste, but you can't miss.

I hope he has tried a paste dispenser before giving up on the reflow oven (Again this may not be his intention, just my interpretation of his note).

I have used 3ml syringes, and tapered plastic needles, which take less pressure to dispense. Dispensing is not a problem. The problem is that it still doesn't save any time or effort for me, personally. In some cases, I fully agree that it could be preferable to stencil-pasting, particularly for low part counts or smaller boards. And of course for one-offs. But it will still be a fairly rare case where I would rather use any kind of paste solder/reflow vs regular hand-soldering.

I have said it before, and I am pretty sure I will follow though. Next time I order enough boards to justify a stencil, I will leave all multi-leaded IC's off the paste layer, because they are the parts that cause me the most egregious issues with paste/reflow, stencil or by hand.

[PlainName]

got tired of cleaning the stencil, squeegee and jig

Yes, that's basically what puts me off too, and the waste of paste. It would be OK if it's being done often, like every day or so.

it leaves unflowed solder paste under parts and behind the pins!

Ah, yes, I've had that. The choice of paste makes a big difference. I think the problem there is the solder melts around the iron and contracts, leaving a ring of not-yet-melted balls. Ideally, they need to be sucked in as the bulk melts, so maybe it's a surface tension vs flux tackiness issue.

[cprrw132]

 G'day Forum members  & visitors  I had the same requirement for a applicator Gun .
 What i came up with was this cockroach gel applicator gun .
  I did have to make a small tin plate to adapt the Soldering flux Syringe to the gun w/- the addition of a needle from a printer ink cartridge kit.
Look up www.easypestsupplies.com.au then cockroach  that leads you to the applicator gun  for Au$12.95 $10.00 freight .
 I now have 2 one I use for pin point flux placement the other  i use for applying  Petroleum jelly into bearings .
  Hope this helps .
 JOHN .
 CPR

[mike_58]

I get frustrated using my hand....

[Jeroen3]

Put in less paste and get less viscose paste.
This one is very soft and has a low temperature to solder very easily using hot air.
http://nl.farnell.com/edsyn/cr44/solder-paste-62-36-2-182-deg-10g/dp/876768

You can populate the entire board with simple components (0805's, SOT-23's and such large pitch stuff) and than use one of those Bosch hot air guns (with digital control) to solder the board.

[zapta]

Thanks nanofrog. They have several tip models. Which one do you recommend for SMD work?

I only have the BON-102 (small fine point nylon brush), so I use it for everything. The brush tip truly does makes a very fine point when it's wet, so it's very nice for SMD work IME (you'll really appreciate it when drag soldering  ). Holds more than enough flux for PTH too (it's fine point, but the brush itself isn't micro sized, so can hold a decent amount of flux).

Prior to trying the Bonkote, I was just dipping inexpensive artist brushes into a tiny well of flux in a porcelain spot plate or using a needle bottle. Found the brush gave the most control, and I figure the brush versions will outlast the felt tips (assuming the felt used is equivalent). And all of it is less expensive than the disposable pens. 

What flux are you using with it?

I tried MG Chemicals 835 but it's too sticky and clogged the head. Then I tried Kester 951 which is thinner and non sticky but doesn't wet as well as the 835.

So far, the best results I got were with the 835 and a small plastic bottle with a thin needle.

[nanofrog]

What flux are you using with it?

I tried MG Chemicals 835 but it's too sticky and clogged the head. Then I tried Kester 951 which is thinner and non sticky but doesn't wet as well as the 835.

So far, the best results I got were with the 835 and a small plastic bottle with a thin needle.

I use both Kester 186 & 1544 in both the brush pen and a needle bottle.

Regarding the MG Chemicals 835, try thinning it out just a bit with some alcohol (or acetone; may have to do this from time to time due to evaporation).