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Non-Waveable SMT Caps

#7031

Non-Waveable SMT Caps | 21 June, 2001

We're doing one of those review things for some reason that none of us can remember.

We just printed-out the product sheets on a whole pantload of SMT capacitors [rather than use the old moldy ones we have in some file cabinet ... BIG mistake] that we glue and then wave solder. We reviewed the new sheets, and found those weenies that make the caps are sayin' we can't wave em, now!!! Webin wavin' em for years!!! Talk about standing around with our mouth aflappin'. Jimminee!!! We're [explative deleted] freaked!!!

Anyone else seein' this? Ifso, what are you doing?

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#7032

Non-Waveable SMT Caps | 22 June, 2001

Oh boy, Oh yes, Oh we�ve seen something similar recently! Had to do with loss of capacitance over time, not that much problem in most of the applications but in our case.... not good at all. Engeneering wrote a - Whatyacallthat?- "changenotice" and the service is required to change that bugger each time a unit takes this extra loop (still have to deal with enough other update stuff especially the SW).

The second more serious "faux pas", our so much loved and only used NC-solder paste turned out to be something else but "NC". Who said that this is NC????... err, mmmh ? , the sales guy did? .... don�t look at me, I wasn�t even working for this company at that time ..... datasheet was in english, couldn�t read it , and similar responses.

Our first, eh second action, sit down, turn of all noise, take some deep breathes, ... out....in ....out...in... - than check if some problems did occur due to this fact ---> no

- can it be left uncleaned on the board? ---> for many applications yes says our supplier and many companies do ( techi over there)

- are our products specified for conditions that we and our customers can live with that? ---> well, at first impression ( and management decision ) , yes

- will have that checked in a Lab soon (as soon as they hand some samples !!!!!)

The rest is hope and pray..

Ah yes, I forgot, the new samples of NC that�re coming in do well at first sight although I noticed a tendency towards solderballs and beadings , have to keep an eye on that, ... but now there�s written down in the datasheets, RESIDUES DON`T NEED TO BE REMOVED

Ahya, Dave, so we all have to carry more or less extra weight on our tour here

Remember to focus on .. in .... out.... out.... , helps a lot

Wolfgang

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#7045

Non-Waveable SMT Caps | 23 June, 2001

Well, at least I don�t feel so bad that we�re not the only ones going anal on this blankin� cap thing. We�re gunna change process on ever effin wave soldered SMT cap!!! I�m going to off myself!!!! And in about 15 seconds, some doodoo brain is going to wander into a meeting and start chattering about reconsidering waving SMT resistors. Yaaaa!!!

"in .... out.... out...." "in .... out.... out...." are you crazy?? I got myself going so fast, I got light-headed, passed-out, and fell over in the corner like a sack of potatoes. Fortunately the fall was cushioned by a stack of old pizza and Krispy Kream boxes. I prefer "in � scream �yaaaa� � in � scream �yaaaa�". It is much more therapeutic. I will admit that all that yelling does seem to wake-up folk taking their afternoon siestas on the line. [Zatt good er bad?? Jury�s still out on that one.]

"Change notice" is something that I�ve been saying a lot lately. "Process change control", that too. "Customer notification", yeh been doin� little of that too. Aint been sayin "product recall" tho [shut yo muth boyi!!!]

Yeow, Non-NC, NC!!! If that happened to me [knock on wood], I�d have new zipper marks on my wrists. We are still OA, cept on one little job where we�re doin� da NC stuff.

"The specification is in English. I don�t read English!!!" Now, that�s a good one!! Gotta figure-out how to use that somewhere.

Yano, that whole NC thing is just seems so "hands-off" from a res stand-point. It just aint natural. Life is not sposed to be that way. You should have to check the stuff. I don�t give a blank what they say on the data sheet. And they always have that weasel words disclaimer down at the bottom, anywho. Caveat Emptor, baybee.

Solder balls & beading: We�ve all talked about the NC paste selection, the too steep a ramp on the profile, the moisture , the too much paste, the excess placement force, the use �home plate� apertures, the lack of board washing, droning on and on; like a low level drumbeat coming in the night a long time before sunrise, while you�re laying there sweating, in a cheap hotel room just off of Rt. 58, just outside of Barstow. Well, here�s a new one. Consider that the gap on yer pads [and as a result apertures, maybe] is too small.

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dave f

#7055

Non-Waveable SMT Caps | 25 June, 2001

are you saying to put a gap in between the board and the stencil? i have been fighting solder balls for a while now. sometimes i can fix them by placement "z" in the machines other times i can't. what should i have my oven profile look like? i have matched alpha's recommendation for the profile as close as i can. should i change my soak time? any advise on this would be greatly appreciated.

bob merriam accuspec electronics

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#7057

Non-Waveable SMT Caps | 25 June, 2001

Who is this, another Dave F ?

For me there�s no problem with balling and beading. I know that the boards I have with the new paste do have all what�s needed for balling and beading, just one of the oldest designs with a stencil ...., oh boy, didn�t know that this thing was laying around here. (trotally wrong pad spacing and apertures 1:1) That�s often the problem that improvements only work for FUTURE products and at PRESENT only the HISTORICAL boards are being build. And especially now with the future cancelled for us the only thing that�s left is build the rest and the last one turns of the light and looks the door.

Sure Dave, the first thing was "... in .. aarrgh ... in ... aarrgh ..." but I corrected myself and said, second "... in .... out ... ", it�s only that some don�t recognize that "aarrgh" anymore, they think I�m a peaceful person and the trouble is, I am.

LEARNED a lot at this place, lots of opportunities

Now, let�s make things better

Wolfgang

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#7070

Non-Waveable SMT Caps | 25 June, 2001

No, I�m suggesting an increase in the distance between the two pads on the board. This "G" in SM-782A "Surface Mount design & Land Pattern Standard" parlance.

You shouldn�t fight solder balls for long periods. You should just increase the pressure in the first wash stage and that will blast the pesky little orbs of solder cleanly from the surface of your board ;-) Ooops, what??? He�s using a flux that leaves no harmful residues, except solder balls, oooo, that�s different. Oh, solder balls and maybe the stuff the Wolfgang found. Notso-No-Clean, ummm, that�s catchy.

Your adjusting "z" makes sense, because that is placement force. Excessive placement force could be splatting the raw solder all over the board, before reflow. Truthfully, a couple of us on the Forum would prefer that you check the SMTnet Archives, tick through the list at the beginning of the paragraph I sent in the above posting, and then poll us on more directed questions.

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#7071

Non-Waveable SMT Caps | 25 June, 2001

Wolfgang: Is your company going-out of business? What "future is canceled"? What lights are being turned-out and doors being locked? Is there a fat lady tuning-up her vocal cords, too? [If so, sympathy.]

Another "Dave F", now that�s something that makes ya sit back in your chair and scratch your head, isn�t it?

I could go with "... in .. aarrgh ... in ... aarrgh ..." � that wouldn�t be bad at all. It was the "in .... out.... out...." bit that just snapped me over the edge.

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#7124

Non-Waveable SMT Caps | 29 June, 2001

Just a quick thought on solder balls "or beads" caused when using NC paste. I found a spec (12.4.10 in IPC-A-610C) that says solder beads are acceptable if they are entrapped in NC flux residue and can not be dislodged in the normal service environment. Any thoughts? Mark

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