Assembly of a Micro-Drive (rkcstr driver) by ME!

[rkcstr]

Re: Assembly of a Micro-Drive (rkcstr driver) by M

If you need supplies like syringes/needle tips, I get stuff from www.smallparts.com.  They're a little pricey for the stuff, but its really a one-time kind of thing since the syringes and needles don't really "go bad".  The tips CAN get clogged if your paste is old or not very good, but you can clean them out with some high percentage isopropyl alcohol (rubbing alcohol).

My suggestions:
1)  I like 3cc syringes, the smaller plunger head means less work for the same pressure compared to larger syringes, but the plunger handle doesn't flex too much like may happen with even smaller syringes.  However, smallparts only carries 1cc or 6cc, I'd probably give the 1cc a try over the 6cc.
2)  You need to find the right gauge needle for your needs.  Too small and you'll get a lot of clogs, it may come out to slowly or just take a lot of force to get the paste out. Too big and you won't have very good control of application, it will come out to fast and just go everywhere.  I use 21ga blunt needles with good results.
3)  To save you some trouble, get fresh paste.  It is typically shipped cold because it is supposed to be kept refrigerated.  I have been using AmTech SynTECH paste, which uses a synthetic flux base and lasts about twice as long as natural flux-based pastes.  It costs about $45 shipped for a 250g jar where I get it (http://www.solderandmore.com/servlet/StoreFront).

 

[691175002]

Re: Assembly of a Micro-Drive (rkcstr driver) by M

Keep in mind that if one has enough skill you can do it the old fashioned way with a soldering iron.  These were both assembled with a soldering iron; it may take longer for many of them, but IMO its more convenient when you don't have the stuff around.

Wouldn't recommend this unless you are confident though.

 

[Spyderz20x6]

Re: Assembly of a Micro-Drive (rkcstr driver) by M

Keep in mind that if one has enough skill you can do it the old fashioned way with a soldering iron.  These were both assembled with a soldering iron; it may take longer for many of them, but IMO its more convenient when you don't have the stuff around.

Wouldn't recommend this unless you are confident though.

Wow!!!
That looks perfect!

 

[rkcstr]

Re: Assembly of a Micro-Drive (rkcstr driver) by M

Keep in mind that if one has enough skill you can do it the old fashioned way with a soldering iron.

Looks good  As shown, you can assemble these circuits well with simply a soldering iron, solder and your hands (flux is helpful too), but it is a more tedious process.  If you're quick, you can probably get one assembled in 5-10min. by hand.  However, as you see in the video, applying paste and placing components might take about 2 min. per driver and then throw them all in the oven for 8 min. and they're done.  If I only have one circuit to build, I'll typically just put it together by hand, but when you're doing 10, 20, 50, reflow is much faster!

Anyway, the video should work now.  YouTube of course denied my dispute, yet I just used the same song (through their Audioswap service).  However, it runs a little short since there were about 1.5 songs playing while I was actually recording it, so don't mind the silence at the end  

 

[Kenom]

Re: Assembly of a Micro-Drive (rkcstr driver) by M

so do you preheat your oven prior to placing your drivers in there or do you heat it after they are in. Second, on what do you place your drivers inside the oven?

 

[rkcstr]

Re: Assembly of a Micro-Drive (rkcstr driver) by M

so do you preheat your oven prior to placing your drivers in there or do you heat it after they are in.  Second, on what do you place your drivers inside the oven?

I use a small toaster oven I got from Walmart a couple years back around Christmas for $15. It has two quartz elements, one on top and one on bottom, which have aluminum shielding covering all but the sides (I assume to prevent direct radiation to the items on the rack). I sit them on the aluminum tray that came with it while reflowing. As for the process, I start at around 200F for about 5 min., then turn it up to 300F for a couple minutes, then up to 400F until the paste starts melting and then let it bake for 30 sec and immediately remove and allow to cool. Careful, when you remove from the oven, the solder may still be "wet" and parts may shift if you jar them around too much.

I don't suggest trying a full-size oven. For one, the temperature control is too sluggish and you'll end up having to spend a lot of time reflowing the boards, possibly burning them. Secondly, the fumes from the flux burning off (or even trace amounts of lead) may leave a toxic residue in the oven that may contaminate food later.

 

[Kenom]

Re: Assembly of a Micro-Drive (rkcstr driver) by M

I purchased a toaster oven at walmart specifically for this purpose and never could use the damn thing cause the racks slits were too big. Like trying to bridge the missisippi with a volkswagen beetle. I tried heating it up first then placing my components on an aluminum tray but they would just sit there and never melt. Of course I don't think my elements were quartz. like inside a blow dryer, it was just wire wrapped around a central fire resistant core.

 

[phoenix3200]

Re: Assembly of a Micro-Drive (rkcstr driver) by M

I got their $40 or $50 model from Wal-Mart that has 4 quartz elements and a fan setting (although I don't use the fan).

What I figured out that worked - after much trial and error (which Rkcstr can attest to), is that:

1.  You need quartz/IR elements.  The normal stove/oven-like heating elements emit way too much radiation, which can turn your boards into a crisp.

2.  Get as thin (and sturdy) of a cooking sheet as possible.  I found that the trays that came with my oven had enough mass that my cooking times slowed down considerably, which also made my boards nice and crispy.

3.  Get a meter with a thermocouple so you can monitor the temperatures.

4.  If you're doing a double-sided board, see if you can do it all at once.  Once again, your board will be crispy if you have to run it through twice.


This is what I do:

1.  Place the components on the thin sheet, and place in the cold oven.

2.  Place the thermocouple end as close as possible to the component(s).

3.  Turn the oven on full blast.  For mine, during the mid-heating phase, this corresponds to about 1 C/s.

4.  Somewhere between 150-170 C, turn off the oven for roughly one minute to make sure the flux gets a chance to work before it evaporates away.

5.  Turn the oven back on full blast, and watch your meter until it reaches 230 C.

6.  Once it reaches 230 C, turn your oven off, leave the door closed, and let it sit until the temperature cools to around 200 C.

7.  Open the door to the oven halfway to let additional heat run out.

8.  Remove the components after your temperature drops below 100 C.

I've probably tried about 12 boards in the toaster oven, and the last six boards I sent through came out perfectly.  Kenom, if you already have SMT components and solder paste on hand, but don't have boards to try them on, send me a PM because I have a bunch of dud boards to get rid of.

 

[rkcstr]

Re: Assembly of a Micro-Drive (rkcstr driver) by M

Yeah, I guess I just got lucky that the super cheap oven I bought had quartz elements... real reflow ovens use IR, so it's good I got the quartz elements    I haven't even tried a different oven, so I don't really know what the other type will do, but I know phoenix3200 does, as he said (crispy boards).

The temps I gave in mine are the just the knob settings on my oven that I use, but I have no idea if those are accurate or not.  The peak temp, 400F, is only just above 200C while most places recommend 230C or so for reflow, but I don't have any problem.

As for the "pre-heat" and stuff, I don't preheat the oven or boards in any way.  I just stick them on the aluminum tray (basically an aluminum sheet), turn the oven to 200F for 5 min. to "dry" the paste and get the boards heated, then up to 300F for 2 min. to bring the board temps up to near melting point, then 400F for 30 seconds after the melt starts to allow complete reflow.

Another critical part of reflow is proper paste application.  Too much paste will cause a high amount of part "wandering", too little and you may get a weak bond or no bond at all.  If you're applying it with a syringe or method other than a stencil, it really is just by experience that you get a feel for it.  But, most times, you really only need a tiny bit of paste to get a good bond. I typically consider pad size compared to component contact size to judge the proper amount. And, the solder bond should be concave rather than convex to get the best bond strength.

 

[Kenom]

Re: Assembly of a Micro-Drive (rkcstr driver) by M

Hmm I wonder if a IR Bulb would do any good.

*wanders off mummbling about IR heat.

 

[Ace82]

Re: Assembly of a Micro-Drive (rkcstr driver) by M

Wow, great video! Looks like you've done that before!

 

[Illuminum3415]

Re: Assembly of a Micro-Drive (rkcstr driver) by M

Yeah, I used to apply solder paste from DX with a toothpick... that was really inefficient.  So, I got some syringes with 23ga needles, cut the needle down to a short tip, filled it up with paste and viola!

I would suggest getting a larger tip, though, maybe 20ga instead of 23ga, as the tip clogs often and I have to take all the paste out, clean the tip and refill it again.  Happens about daily or every other day.

Some more tips I have:

1.  get GOOD solder paste.  I now use AMTECH SynTECH solder paste, was about $40 for 250g from www.solderandmore.com , which will last a long time, and it keeps twice as long as regular paste (1yr cold vs 6mo for most).  DX paste will clog tips like no other, so I'd avoid it unless you're a very patient person.

2.  Keep the syringe with paste (and your extra paste) in the fridge when you're not using it, it tends to keep the paste from settling and clogging the tips as quickly.

3.  I have yet to buy from them, but when I need new syringes and tips, I'm getting them from here:
http://www.smallparts.com/s?searchN...28182011|3180231&searchKeywords=blunt+needles

Thank you for this information! I was like...how the @#$% do you apply solder paste using a syringe when they will clog it in a couple hours to a couple days depending on the ambient temperature it was stored in. Dx paste = no good

So what happens after the solder paste is set? do you hit it with a hot air gun? reflow [which I have no clue how if you've applied paste to both sides], or do you hover the iron over the contacts and let it do its magic? :

note to self: toss the chiesel tip and get meself one with a pencil tip ;D

 

[potatorage]

Re: Assembly of a Micro-Drive (rkcstr driver) by M

[quote author=rkcstr link=1216770010/0#10 date=1216821380]Yeah, I used to apply solder paste from DX with a toothpick... that was really inefficient.  So, I got some syringes with 23ga needles, cut the needle down to a short tip, filled it up with paste and viola!

I would suggest getting a larger tip, though, maybe 20ga instead of 23ga, as the tip clogs often and I have to take all the paste out, clean the tip and refill it again.  Happens about daily or every other day.

Some more tips I have:

1.  get GOOD solder paste.  I now use AMTECH SynTECH solder paste, was about $40 for 250g from www.solderandmore.com , which will last a long time, and it keeps twice as long as regular paste (1yr cold vs 6mo for most).  DX paste will clog tips like no other, so I'd avoid it unless you're a very patient person.

2.  Keep the syringe with paste (and your extra paste) in the fridge when you're not using it, it tends to keep the paste from settling and clogging the tips as quickly.

3.  I have yet to buy from them, but when I need new syringes and tips, I'm getting them from here:
http://www.smallparts.com/s?searchN...28182011|3180231&searchKeywords=blunt+needles

Thank you for this information! I was like...how the @#$% do you apply solder paste using a syringe when they will clog it in a couple hours to a couple days depending on the ambient temperature it was stored in. Dx paste = no good

So what happens after the solder paste is set? do you hit it with a hot air gun? reflow [which I have no clue how if you've applied paste to both sides], or do you hover the iron over the contacts and let it do its magic? :

note to self: toss the chiesel tip and get meself one with a pencil tip  ;D
[/quote]


Use a toaster oven

 

[Mohrenberg]

Re: Assembly of a Micro-Drive (rkcstr driver) by M

haha i had no idea a toaste oven was even an option, i just figured it would ruin the components, i didn't ven know they had flux with solder in it in a paste form.

i was just forced to learn how to micro solder with a big ass soldering iron.....and i'm pretty damn good as it now too

 

[rkcstr]

Re: Assembly of a Micro-Drive (rkcstr driver) by M

Yes, you can use a toaster oven, but as others have found, you must have one that uses a quartz element, not the usual black elements like you see on an electric stove.  The quartz element essentially produces an IR oven, which is exactly what a real small reflow oven is, just with less fancy electronics and probably not quite as even heat distribution.  The element looks like a translucent rod, so just look for that.  They can be found for cheap, you just have to look... I found one at Walmart a couple years back for $15, not on clearance!  

Also, DO NOT USE AN OVEN THAT YOU ALSO COOK FOOD IN!!!  You're likely using paste with lead in it, and I can't say for sure, but I would bet that at least trace amounts of lead are vaporized or aerosolized and deposited on the walls/rack of the oven.  And the flux gives off a nasty odor when it is cooked off, which I'm guessing is probably not healthy either.  So, if you're going to use an oven, but a new one for reflow, not the one your mom, wife, girlfriend, friends or YOU use to cook food!

 

[AusLasersSuck]

Re: Assembly of a Micro-Drive (rkcstr driver) by M

How much does it cost for all the parts to make ONE.