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How are your solder balls @ wave solder ?

JohnW

#9054

How are your solder balls @ wave solder ? | 10 October, 1999

Folk's,

I'm just tying up some loose end's on my Master's Thesis on solderballing @ wave soldering and the effect the topography of the mask / PCB has on it. I was wanting to do a straw poll on you guy's as to the type of resist's you are using Gloss / matte, whether your using clean or no clean flux and so on. I'm trying to guage what the industry std is ( if there is one) and so add in some more 'real life' other than what I've seen already.

Thanks in advance gang

JohnW

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Brian

#9055

Re: How are your solder balls @ wave solder ? | 11 October, 1999

| Folk's, | | I'm just tying up some loose end's on my Master's Thesis on solderballing @ wave soldering and the effect the topography of the mask / PCB has on it. | I was wanting to do a straw poll on you guy's as to the type of resist's you are using Gloss / matte, whether your using clean or no clean flux and so on. | I'm trying to guage what the industry std is ( if there is one) and so add in some more 'real life' other than what I've seen already. | | Thanks in advance gang | | JohnW | John

If we tell you, do we get a master's degree, as well? :-)

Seriously, the finish of the solder mask should not affect solder balling. What can do is the degree of cure or the Tg of the mask. If a mask is rock hard, the ball should not normally adhere, except to the flux layer. Most masks are less than ideal and can soften slightly under the ball, sufficiently to form a little conformal 'dimple' which tends to retain it in place. However, there is usually sufficient mechanical action in cleaning to displace the ball. The real problem is with "no-clean" where cleaning is not done and the ball embeds itself into both the flux layer and the mask dimple. This can be exacerbated by insufficient preheat, causing the solder to spatter as the flux solvent evaporates on hitting the wave, particularly with so-called VOC-free "no-clean" fluxes (which are not VOC-free, at all, but that's another story).

Hope this helps.

Brian

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#9056

Re: How are your solder balls @ wave solder ? | 11 October, 1999

| | Folk's, | | | | I'm just tying up some loose end's on my Master's Thesis on solderballing @ wave soldering and the effect the topography of the mask / PCB has on it. | | I was wanting to do a straw poll on you guy's as to the type of resist's you are using Gloss / matte, whether your using clean or no clean flux and so on. | | I'm trying to guage what the industry std is ( if there is one) and so add in some more 'real life' other than what I've seen already. | | | | Thanks in advance gang | | | | JohnW | | | John | | If we tell you, do we get a master's degree, as well? :-) | | Seriously, the finish of the solder mask should not affect solder balling. What can do is the degree of cure or the Tg of the mask. If a mask is rock hard, the ball should not normally adhere, except to the flux layer. Most masks are less than ideal and can soften slightly under the ball, sufficiently to form a little conformal 'dimple' which tends to retain it in place. However, there is usually sufficient mechanical action in cleaning to displace the ball. The real problem is with "no-clean" where cleaning is not done and the ball embeds itself into both the flux layer and the mask dimple. This can be exacerbated by insufficient preheat, causing the solder to spatter as the flux solvent evaporates on hitting the wave, particularly with so-called VOC-free "no-clean" fluxes (which are not VOC-free, at all, but that's another story). | | Hope this helps. | | Brian | I have found that a matte finish significantly reduces the number of solder balls that remain adhered to the board after soldering. Whether this is due to reduced production of balls or fewer of them sticking I do not know. We use a no clean/VOC free flux. John Thorup

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#9057

Re: How are your solder balls @ wave solder ? | 11 October, 1999

| | Folk's, | | | | I'm just tying up some loose end's on my Master's Thesis on solderballing @ wave soldering and the effect the topography of the mask / PCB has on it. | | I was wanting to do a straw poll on you guy's as to the type of resist's you are using Gloss / matte, whether your using clean or no clean flux and so on. | | I'm trying to guage what the industry std is ( if there is one) and so add in some more 'real life' other than what I've seen already. | | | | Thanks in advance gang | | | | JohnW | | | John | | If we tell you, do we get a master's degree, as well? :-) | | Seriously, the finish of the solder mask should not affect solder balling. What can do is the degree of cure or the Tg of the mask. If a mask is rock hard, the ball should not normally adhere, except to the flux layer. Most masks are less than ideal and can soften slightly under the ball, sufficiently to form a little conformal 'dimple' which tends to retain it in place. However, there is usually sufficient mechanical action in cleaning to displace the ball. The real problem is with "no-clean" where cleaning is not done and the ball embeds itself into both the flux layer and the mask dimple. This can be exacerbated by insufficient preheat, causing the solder to spatter as the flux solvent evaporates on hitting the wave, particularly with so-called VOC-free "no-clean" fluxes (which are not VOC-free, at all, but that's another story). | | Hope this helps. | | Brian | Brian: Surface energy of the solder mask play a big part in solder ball formation. Read:

Solder Resist & Solder balls - John Watt 10:59:20 12/22/1998

My 2�

Dave F

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#9058

Re: How are your solder balls @ wave solder ? | 11 October, 1999

| Folk's, | | I'm just tying up some loose end's on my Master's Thesis on solderballing @ wave soldering and the effect the topography of the mask / PCB has on it. | I was wanting to do a straw poll on you guy's as to the type of resist's you are using Gloss / matte, whether your using clean or no clean flux and so on. | I'm trying to guage what the industry std is ( if there is one) and so add in some more 'real life' other than what I've seen already. | | Thanks in advance gang | | JohnW | John: Matt/clean, semi-matt (??)/clean, matt/no-clean. Ta. Dave F

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JohnW

#9059

Re: How are your solder balls @ wave solder ? | 14 October, 1999

Sorry Dave should have said...

At the mo all my data is for no clean processes using both matte and gloss finishes. That doesn't mean your feedback has to be limited to this area, I'm really trying to find out what the rest of the world are doing if you like and then I can use that to say well here are some saving's or advantages of this or the failing's and so on.

Thanks johnW

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JohnW

#9060

Re: How are your solder balls @ wave solder ? | 14 October, 1999

Gee Dave That's the first time I've ever seen myself listed for a quote!

Brian, what your saying is on the whole right, on the surface of it the mask, as long as it's cured properlay shouldn't make a difference but I have to say that I've found so far that it does seem to be which is why I've asked for the feedback. Yes the main culprate now is ball's being trapped in the flux, but what if your resist was reducing the availability of the flux to remove the posibility of it entrapping the solder ball ?, this is the effect that I believe I'm seeing with the matt finish due to the increase in surface area for the flux but a reduction in available surface area for the solderball's to wet to due to the peak and trough effect of a matte resist.

JohnW

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