Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Larry Johnson

#14350

Double-sided reflow with BGA??? Can it be done? | 10 September, 1998

I was wanting to know if double sided reflow can be done with a metal plated BGA on topside. We would be running bottom side first. My boss seems to think the only way it can be done is by placing glue dots on the bottomside compoents because the BGA will soak too much heat, therefore causing the bottom side parts to fall off. I believe it can be done WITHOUT glue. He doesn't think the same. I gues my questions is: Is glue the right way to go... or just a correctly profiled oven. Does glue cause any problems? Thanks.....

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Dave F

#14358

Re: Double-sided reflow with BGA??? Can it be done? | 10 September, 1998

| I was wanting to know if double sided reflow can be done with a metal plated BGA on topside. We would be running bottom side first. My boss seems to think the only way it can be done is by placing glue dots on the bottomside compoents because the BGA will soak too much heat, therefore causing the bottom side parts to fall off. I believe it can be done WITHOUT glue. He doesn't think the same. I gues my questions is: Is glue the right way to go... or just a correctly profiled oven. Does glue cause any problems? | Thanks..... Larry: I'm not sure what a "metal plated BGA" is, but that not letting that impare my willingnss to respond, it's possible (depending on the type of oven your using) that your boss is correct. That being said, if you have a fairly modern forced air convection oven, there is no apparent reason to glue the second side components. Hey what's the big deal? Paste one of those puppies-up and run it, as you planned. Worst case you hand solder components that fall-off and move forward with adhesives in the future. You are no worse off than if you started with adhesives in the first place. Good luck Dave F

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Earl Moon

#14357

Re: Double-sided reflow with BGA??? Can it be done? | 10 September, 1998

| I was wanting to know if double sided reflow can be done with a metal plated BGA on topside. We would be running bottom side first. My boss seems to think the only way it can be done is by placing glue dots on the bottomside compoents because the BGA will soak too much heat, therefore causing the bottom side parts to fall off. I believe it can be done WITHOUT glue. He doesn't think the same. I gues my questions is: Is glue the right way to go... or just a correctly profiled oven. Does glue cause any problems? | Thanks..... Without telling how, I will answer your question as a big YES. I'm not trying to be evasive, though obviously I am, but I did this about 5 years ago and continue to do so. It's not magic, but it does take some work and careful preparation. Judging from your attitude, I bet you'll find the way just as I did. Earl Moon

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Wayne Bracy

#14356

Re: Double-sided reflow with BGA??? Can it be done? | 11 September, 1998

| I was wanting to know if double sided reflow can be done with a metal plated BGA on topside. We would be running bottom side first. My boss seems to think the only way it can be done is by placing glue dots on the bottomside compoents because the BGA will soak too much heat, therefore causing the bottom side parts to fall off. I believe it can be done WITHOUT glue. He doesn't think the same. I gues my questions is: Is glue the right way to go... or just a correctly profiled oven. Does glue cause any problems? | Thanks..... Larry: I agree with Earl and Dave, give it a try. Watch your solder screen process, placement, and oven profile, but you should be able to perform double sided reflow without any glue.... Worse case would be you have to hand place and solder a few components or perform a glue dot process. Wayne

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Justin Medernach

#14354

Re: Double-sided reflow with BGA??? Can it be done? | 11 September, 1998

| I was wanting to know if double sided reflow can be done with a metal plated BGA on topside. We would be running bottom side first. My boss seems to think the only way it can be done is by placing glue dots on the bottomside compoents because the BGA will soak too much heat, therefore causing the bottom side parts to fall off. I believe it can be done WITHOUT glue. He doesn't think the same. I gues my questions is: Is glue the right way to go... or just a correctly profiled oven. Does glue cause any problems? | Thanks..... Larry, I've built a bazillion assemblies using double sided reflow. I work for a prototype assembly shop so I've seen quite a diverse product mix. I very very rarely use any adhesive. You don't need any for this application. You'll be able to profile around it. Regards, Justin Medernach

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Earl Moon

#14355

Re: Double-sided reflow with BGA??? Can it be done? | 11 September, 1998

| | I was wanting to know if double sided reflow can be done with a metal plated BGA on topside. We would be running bottom side first. My boss seems to think the only way it can be done is by placing glue dots on the bottomside compoents because the BGA will soak too much heat, therefore causing the bottom side parts to fall off. I believe it can be done WITHOUT glue. He doesn't think the same. I gues my questions is: Is glue the right way to go... or just a correctly profiled oven. Does glue cause any problems? | | Thanks..... | Larry, | I've built a bazillion assemblies using double sided reflow. I work for a prototype assembly shop so I've seen quite a diverse product mix. I very very rarely use any adhesive. You don't need any for this application. You'll be able to profile around it. | Regards, | Justin Medernach Justin, I knew you'd blow me out of the water with my little secrets. I'll bet mine is better than yours, but then you have no secrets. I called you Jason in the answer above concerning fine pitch. Instead of retracting it, would you consider a name change? Most respectfully, Earl Moon

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Rick Bell

#14352

Re: Double-sided reflow with BGA??? Can it be done? | 12 September, 1998

| I was wanting to know if double sided reflow can be done with a metal plated BGA on topside. We would be running bottom side first. My boss seems to think the only way it can be done is by placing glue dots on the bottomside compoents because the BGA will soak too much heat, therefore causing the bottom side parts to fall off. I believe it can be done WITHOUT glue. He doesn't think the same. I gues my questions is: Is glue the right way to go... or just a correctly profiled oven. Does glue cause any problems? | Thanks.....

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Rick Bell

#14353

Re: Double-sided reflow with BGA??? Can it be done? | 12 September, 1998

| | | I was wanting to know if double sided reflow can be done with a metal plated BGA on topside. We would be running bottom side first. My boss seems to think the only way it can be done is by placing glue dots on the bottomside compoents because the BGA will soak too much heat, therefore causing the bottom side parts to fall off. I believe it can be done WITHOUT glue. He doesn't think the same. I gues my questions is: Is glue the right way to go... or just a correctly profiled oven. Does glue cause any problems? | | Thanks..... Larry, sorry, missed my comments on my first post. I'm assuming that your company is attempting to use a forced convection type of reflow process. your Boss's comments may be related to older IR technology; I could understand some potential difficulties if that's the case, especially with super BGA packages-- these tend to present significant "shadow" areas. However, under the assumption that you are using forced convection, I agree with the other respondants... Double Sided Reflow of BGA's should not require any adhesive. regards, Rick Bell

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Chrys

#14351

Re: Double-sided reflow with BGA??? Can it be done? | 15 September, 1998

| I was wanting to know if double sided reflow can be done with a metal plated BGA on topside. We would be running bottom side first. My boss seems to think the only way it can be done is by placing glue dots on the bottomside compoents because the BGA will soak too much heat, therefore causing the bottom side parts to fall off. I believe it can be done WITHOUT glue. He doesn't think the same. I gues my questions is: Is glue the right way to go... or just a correctly profiled oven. Does glue cause any problems? | Thanks..... Larry This month's Circuits Assembly Magazine has an article on double sided BGA reflow. Don't know if you read it yet. Can't look it up right now; mine's at home.

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