Wave Solder balls

Well my process is I'm running my belt speed at 3.50fpm and about 215 to 225 degrees top side. I got my main wave down to a little less than half the board thickness. I'm not using a hot air knife cause we thought it might create more of a problem than good. I do have a foam fluxer with air knife at a 10 degree incline (toward the load end. I looked in the manual and could not find what the psi setting should be at for the air knife. I got up at about 10 psi. My solder balls problem is that it sticks to the mask and the fluxed bare board itself. But when I send through the DI wash it is washed away. Could this be the cause of my bridging?How can I tell when I got too much flux on the board and the preheaters did not cure the flux? Any help or info will be greatly appreciated. =)

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| Well my process is I'm running my belt speed at 3.50fpm and about 215 to 225 degrees top side. I got my main wave down to a little less than half the board thickness. I'm not using a hot air knife cause we thought it might create more of a problem than good. I do have a foam fluxer with air knife at a 10 degree incline (toward the load end. I looked in the manual and could not find what the psi setting should be at for the air knife. I got up at about 10 psi. My solder balls problem is that it sticks to the mask and the fluxed bare board itself. But when I send through the DI wash it is washed away. Could this be the cause of my bridging?How can I tell when I got too much flux on the board and the preheaters did not cure the flux? Any help or info will be greatly appreciated. =) | Hey Michael-

I would say your settings look pretty good. You might try raising your topside preheat levels about 15 deg. on each end of your given range, if you have the room to ramp at a decent rate. . This may help a little in driving that flux off. Are you using no-clean, water-soluble, RMA flux? IS it VOC-free, or alcohol based? If you are using VOC-free, it will be more difficult to drive the flux completely off. I wish I could help you with your air knife settings, as that would influence the amount of flux on the board, but I have little experience with those things. Good Luck!

Ryan Jennens Phoenix Engineering Design, Inc. Lansing, MI

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Micheal,

What does your profile look like for the wave? What profile does your flux say you need? My guess is it is not your profile, our testing with solder balls found that the mask on the boards was the largest contributor to solder balls. What type of mask are you using? We sent to Dexter Hysol: SR8200R to eliminate solder balls, it worked pretty well. We don't have nearly the problem with solder balls that we used to. Unfortunately, it causes a problem with the adhesive sticking to the board also. Further testing has led us to Enthone DSR3241MD. Good Luck, Kelly

| | Well my process is I'm running my belt speed at 3.50fpm and about 215 to 225 degrees top side. I got my main wave down to a little less than half the board thickness. I'm not using a hot air knife cause we thought it might create more of a problem than good. I do have a foam fluxer with air knife at a 10 degree incline (toward the load end. I looked in the manual and could not find what the psi setting should be at for the air knife. I got up at about 10 psi. My solder balls problem is that it sticks to the mask and the fluxed bare board itself. But when I send through the DI wash it is washed away. Could this be the cause of my bridging?How can I tell when I got too much flux on the board and the preheaters did not cure the flux? Any help or info will be greatly appreciated. =) | | | Hey Michael- | | I would say your settings look pretty good. You might try raising your topside preheat levels about 15 deg. on each end of your given range, if you have the room to ramp at a decent rate. . This may help a little in driving that flux off. Are you using no-clean, water-soluble, RMA flux? IS it VOC-free, or alcohol based? If you are using VOC-free, it will be more difficult to drive the flux completely off. I wish I could help you with your air knife settings, as that would influence the amount of flux on the board, but I have little experience with those things. Good Luck! | | Ryan Jennens | Phoenix Engineering Design, Inc. | Lansing, MI | |

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| Well my process is I'm running my belt speed at 3.50fpm and about 215 to 225 degrees top side. I got my main wave down to a little less than half the board thickness. I'm not using a hot air knife cause we thought it might create more of a problem than good. I do have a foam fluxer with air knife at a 10 degree incline (toward the load end. I looked in the manual and could not find what the psi setting should be at for the air knife. I got up at about 10 psi. My solder balls problem is that it sticks to the mask and the fluxed bare board itself. But when I send through the DI wash it is washed away. Could this be the cause of my bridging?How can I tell when I got too much flux on the board and the preheaters did not cure the flux? Any help or info will be greatly appreciated. =) | Mike: This is the portion our wave set-up procedure that applies to a foam fluxer setup. Dave F

4.1.2 Foam Fluxer 4.1.2.1 Check that the flux head is stable and not changing height or "moving around." 4.1.2.2 Adjust the air pressure to get the smallest bubbles 4.1.2.3 Use an unsoldered board or a "Lev Check," confirm that good contact is being made with the foam head. 4.1.2.4 Inspect the board: There should be:

� A thin coating of flux over the complete board. � Evidence that the flux has just entered the through holes.

NOTE: The "Lev Check" depresses the foam head. Check that the foam bubbles making contact are relatively small and there is uniform coverage across the plate.

4.2 Set-Up the Fluxer Air Knife. It�s easy to overcoat the board with flux and get good results, the trick is to get good results with a minimum deposit. 4.2.1 Beginning with the air knife set at 90� to the board, adjust the air knife to meet the following two purposes: 4.2.1.1 Remove excess flux from the surface of the board. 4.2.1.2 Drive the flux vertically into the plated through holes. 4.2.2 Check flux penetration into the through holes. 4.2.2.1 Place a piece of thermal fax paper on the top side of the un-populated printed board 4.2.2.2 Pass the board and paper through the fluxing system. 4.2.2.3 Check for evidence of the flux wetting of the paper at the through holes. 4.3 Determine the amount of flux on the board. 4.3.1 Get a piece of corrugated cardboard and a weighing scale accurate to 0.01 grams.

NOTE: Use cardboard with alcohol fluxes to slow their evaporation and get good data.

4.3.2 Weigh the cardboard. 4.3.3 Run the cardboard across the fluxer. 4.3.4 Weigh the cardboard again. 4.3.5 Calculate change in weight / area of the cardboard 4.3.6 Determine flux density. 4.3.7 Ask the flux manufacturer to calculate the flux deposition as: (Change in weight / area) X % solids by weight. 4.3.8 Convert the flux deposition to micro-grams/square inch and compare it to the manufacturer's recommendation.

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| Micheal, | | What does your profile look like for the wave? What profile does your flux say you need? My guess is it is not your profile, our testing with solder balls found that the mask on the boards was the largest contributor to solder balls. What type of mask are you using? We sent to Dexter Hysol: SR8200R to eliminate solder balls, it worked pretty well. We don't have nearly the problem with solder balls that we used to. Unfortunately, it causes a problem with the adhesive sticking to the board also. Further testing has led us to Enthone DSR3241MD. | Good Luck, | Kelly | | | | Well my process is I'm running my belt speed at 3.50fpm and about 215 to 225 degrees top side. I got my main wave down to a little less than half the board thickness. I'm not using a hot air knife cause we thought it might create more of a problem than good. I do have a foam fluxer with air knife at a 10 degree incline (toward the load end. I looked in the manual and could not find what the psi setting should be at for the air knife. I got up at about 10 psi. My solder balls problem is that it sticks to the mask and the fluxed bare board itself. But when I send through the DI wash it is washed away. Could this be the cause of my bridging?How can I tell when I got too much flux on the board and the preheaters did not cure the flux? Any help or info will be greatly appreciated. =) | | | | | Hey Michael- | | | | I would say your settings look pretty good. You might try raising your topside preheat levels about 15 deg. on each end of your given range, if you have the room to ramp at a decent rate. . This may help a little in driving that flux off. Are you using no-clean, water-soluble, RMA flux? IS it VOC-free, or alcohol based? If you are using VOC-free, it will be more difficult to drive the flux completely off. I wish I could help you with your air knife settings, as that would influence the amount of flux on the board, but I have little experience with those things. Good Luck! | | | | Ryan Jennens | | Phoenix Engineering Design, Inc. | | Lansing, MI | | | | | | If you're having solder mask problems, it probably isn't the brand of mask (unless it's dry film). It is the process used to apply it. Doing a better job of evaluating PCB fab suppliers is the answer here, not replacing masks.

Earl Moon

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