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SAC305 Solder Balling

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CL

#43176

SAC305 Solder Balling | 4 August, 2006

Good Morning Everyone,

We have started limited production runs of RoHS assemblies. Most of them are prototypes for our customers that are converting to Lead Free. We have seen on several assemblies, solder beads under the chip components that are entrapped. The curious thing is that we are not seeing the same results on all of our RoHS assemblies. We are using the same paste for all. The pad sizes are correct for the component. We are unable to reduce the placement force beyond 3 newtons and we actually saw solder beads under a component that was hand placed.

Has anyone else experienced similar problems?

Any help would be greatly appreciated.

Thanks In Advance

Chris

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aj

#43178

SAC305 Solder Balling | 4 August, 2006

Hi,

Have you incorporated any Aperture Modifications in your stencil.( i.e. Homebase / 10% reductions).

I have a similiar problem here with one of our high volume builds and I am in the process of ordering a new stencil with recommeded aperture reductions / modifications.

I am confident that this will sort out the problem of mid-chip solder balling.

aj...

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RDR

#43185

SAC305 Solder Balling | 4 August, 2006

Aj is right, utilize the homeplate aperture, this reduces the amount of paste actually underneath the component, Pb frees exhibit this mid ship more often than the lead, I think,it is mostly because of thre transition to noclean form water solubles and the poor/reduced wetting of the SAC alloy.

Russ

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cuculi54986@yahoo.com

#43301

SAC305 Solder Balling | 14 August, 2006

I agree with using the homeplate design on chips. Some Pb-free solder paste manufacturers recommend 1:1 apertures. This, in my experience, is not a good idea with any of the SAC305 pastes I've tried.

I've been using the same stencil design guidelines for Pb-free that I use for leaded assemblies. It seems to work very well.

Luckily for me, our boards are not all that complicated (no BGA's, no 0201's, no CSP).

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McGill

#43341

SAC305 Solder Balling | 15 August, 2006

Ball SAC is hard to overcome. Try RSS profile

This message was posted Add this forum to your site! Click to learn more. the Electronics Forum @

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McGill

#43342

SAC305 Solder Balling | 15 August, 2006

Ball SAC is hard to overcome. Try RSS profile

This message was posted Add this forum to your site! Click to learn more. the Electronics Forum @

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Chunks

#43344

SAC305 Solder Balling | 15 August, 2006

Ball SACs are not hard to over come. Most people solder these devices well using a straight ramp with a slight knee right before liquidous. Ramp-soak-and spike would not an ideal way to reflow.....

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McGill

#43366

SAC305 Solder Balling | 17 August, 2006

I happen to be an old lead head from way back, and I don't agree with all this straight ramp garbage. This makes me so mad I'm going to do Tai Chi to calm myself down.

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RDR

#43369

SAC305 Solder Balling | 17 August, 2006

Well my friend, flux chemistries have changed. I do not want to drive you over edge but I use a straight ramp for lead as well!!!! Let the product dictate process!! I only soak when the delta T is not manageable with straight ramp.

Please do not do anything rash!!!, maybe even try one for fun some day. see what happens.

hehehe

Russ

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Chunks

#43373

SAC305 Solder Balling | 17 August, 2006

Hi McGill,

The straight ramp is "straight" from the manufacturers of the material. Using old process techniques from your old process materials no longer applies. We all miss the good old days, but it�s time to move on.

Being of Asian descent, I too practice Tai. It�s all about finding your natural euphoria by kicking in them endorphins. You should perform it in the morning during the sun rise. This should block anger from your Chi all day. Perhaps it�s something besides new technology that upsets you � in that case I suggest reading The Yin-Yang Butterfly (no affiliation).

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McGill

#43384

SAC305 Solder Balling | 17 August, 2006

You are ignorant in the art of Tai Chi my friend. I would suggest formal lessons from a Tai Chi Master.

This message was posted Add this forum to your site! Click to learn more. the Electronics Forum @

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McGill

#43385

SAC305 Solder Balling | 17 August, 2006

You are ignorant in the art of Tai Chi my friend. I would suggest formal lessons from a Tai Chi Master.

This message was posted Add this forum to your site! Click to learn more. the Electronics Forum @

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Chunks

#43386

SAC305 Solder Balling | 17 August, 2006

Hi McGill,

Wow, another "Master" in the making on this forum. Call me what you will, at least I know how to post once.

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chrisgriffin

#43387

SAC305 Solder Balling | 17 August, 2006

Does anyone else find it really annoying when people post the same thing twice?

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#43389

SAC305 Solder Balling | 17 August, 2006

Not so much when I suspect it's a function of age. ;)

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