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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Brian Conner

#15282

Capacitor Wave Soldering Woes | 23 June, 1998

I am experiencing a wave-soldering problem with a leaded capacitor - too much solder above the board!! The capacitor lead is .020" dia. and the hole size is .038". This only occurs on the negative lead of the component. The capacitor is also axial-inserted. The solder wets up over the bend radius and remains too close to the body of the component - within one lead diameter. It resembles a "cocoon" as most of the solder will go back down the hole. Does anyone have any ideas of what the root cause could be? The boards are fairly large and is heavily populated with SMT and leaded components. The board thickness is .063" and the topside preheat is 200-210 F. This is not isolated to one board, rather, it encompasses quite a few boards of varying sizes. I figure if I can get to the root cause on this board that I might be able to take care of the rest of the boards. Thanks in advance

reply »

D.Lange

#15286

Re: Capacitor Wave Soldering Woes | 23 June, 1998

| I am experiencing a wave-soldering problem with a leaded capacitor - too much solder above the board!! The capacitor lead is .020" dia. and the hole size is .038". This only occurs on the negative lead of the component. The capacitor is also axial-inserted. | The solder wets up over the bend radius and remains too close to the body of the component - within one lead diameter. It resembles a "cocoon" as most of the solder will go back down the hole. Does anyone have any ideas of what the root cause could be? The boards are fairly large and is heavily populated with SMT and leaded components. The board thickness is .063" and the topside preheat is 200-210 F. This is not isolated to one board, rather, it encompasses quite a few boards of varying sizes. I figure if I can get to the root cause on this board that I might be able to take care of the rest of the boards. | Thanks in advance Increase preheat to 215-230 if that dont work then solder temp is probably too low. When is last time you had solder analized?

reply »

Brian Conner

#15287

Re: Capacitor Wave Soldering Woes | 24 June, 1998

| | I am experiencing a wave-soldering problem with a leaded capacitor - too much solder above the board!! The capacitor lead is .020" dia. and the hole size is .038". This only occurs on the negative lead of the component. The capacitor is also axial-inserted. | | The solder wets up over the bend radius and remains too close to the body of the component - within one lead diameter. It resembles a "cocoon" as most of the solder will go back down the hole. Does anyone have any ideas of what the root cause could be? The boards are fairly large and is heavily populated with SMT and leaded components. The board thickness is .063" and the topside preheat is 200-210 F. This is not isolated to one board, rather, it encompasses quite a few boards of varying sizes. I figure if I can get to the root cause on this board that I might be able to take care of the rest of the boards. | | Thanks in advance | Increase preheat to 215-230 if that dont work then solder temp is probably too low. When is last time you had solder analized? Solder is analyzed monthly by an outside lab not associated with our solder vendor. The increase in topside preheat has been attempted with dewetting of SMT topside components. Thanks for the information.

reply »

Chris Kelly

#15283

Re: Capacitor Wave Soldering Woes | 24 June, 1998

What is your current solder pot temperature? Whatever that temperature is, has it been verified/calibrated? What kind of flux is being used? No-clean, OA, RMA? How is the flux being applied to the PCB? Is this problem occuring on ALL negative terminals of ALL thru hole caps? If not, does this happen consistently to the SAME caps each time? Lastly, what is your conveyor speed? solder dwell time?

reply »

Brian Conner

#15284

Re: Capacitor Wave Soldering Woes | 24 June, 1998

| What is your current solder pot temperature? Whatever that temperature is, | has it been verified/calibrated? | What kind of flux is being used? No-clean, OA, RMA? | How is the flux being applied to the PCB? | Is this problem occuring on ALL negative terminals of ALL thru hole caps? | If not, does this happen consistently to the SAME caps each time? | Lastly, what is your conveyor speed? solder dwell time? The Lonco 3355-11 flux is sprayed on. The Electrovert Ultra2000 conveyor speed is at 3.00 ft/min and the solder bath is set at 480 F. The temperature and conveyor speeds are verified on a dailly basis per our P.M. setup. A QA audit profile is also done once every 3 days to substantiate maintenance's findings. This does not happen to other capacitors, nor does it occur on the same capacitors on a consistent basis. Rather, on a board with 16 capacitors that are arranged in no uniform pattern, will have 3 to 4 capacitors with this issue. The next board will have the same number of defects, but on different capacitors. My thinking is starting to slide towards the Axial insertion of the component in relationship to the smaller dia. of the lead. What do ya think?

reply »

Chris Kelly

#15285

3355-11 Uh oh! | 24 June, 1998

Brian, a couple of things really stick out here... 1) You are spraying what is referred to here at the CATT as "PINK DEATH" The 3355-11 is about the most active/aggressive flux you can get your hands on. I am concerned about both the condition of the wave solder machine as well as the spray fluxer. Unless you have setup a super rigourous cleaning schedule, this flux will fairly quickly 'eat' your machine and fluxer. 2) You're running a conveyor speed of 3 ft./min. Without knowing details like the board thickness, density, etc., I would be inclined to say that this slow of a speed would not be necessary given the high activity of flux. It is possible that your 'defect' (some of our customers would kill to have this kind of problem)is a result of the Super Wetting Syndrone. Naturally, this is a fictitous term but you get the idea. My suggestion would be to first try running a board at a faster conveyor speed. Or, if you don't want to re-adjust your preheat to match the new speed, you can run the board at 3 ft/min through the PH, and then quickly change the speed via the keypad to something like 5 or 6 ft/min just before the board enters the wave. This will help to identify whether or not your dwell time is excessive for this particular flux and/or situation. Less dwell time could possibly alleviate this 'problem'. My second suggestion would be to decrease your flux deposition rate. I don't know what type of spray fluxer you're using, but I would say try cutting it in half. When using 3355-11, it only takes a pinch to do the job. Less wetting forces mean less wicking. Less wicking means less top-side hole fill. Now, you say that it doesn't occurr on every cap every time. This could be an indication that there is either a contamintion issue with some of the leads, or an oxidation problem if the parts have been sitting around for excessive periods of time. It could also be due to fluxer performance issues. The fluxer could be performing erraticly and depositing a non-uniform layer of flux on the board. Or, if you'd like to talk to me personally, you can contact me at 972-606-1900 x183 I am the SW regional Product Specialist for Wave Solder here at Speedline/Electrovert. deposition | The Lonco 3355-11 flux is sprayed on. The Electrovert Ultra2000 conveyor speed is at 3.00 ft/min and the solder bath is set at 480 F. The temperature and conveyor speeds are verified on a dailly basis per our P.M. setup. A QA audit profile is also done once every 3 days to substantiate maintenance's findings. | This does not happen to other capacitors, nor does it occur on the same capacitors on a consistent basis. Rather, on a board with 16 capacitors that are arranged in no uniform pattern, will have 3 to 4 capacitors with this issue. The next board will have the same number of defects, but on different capacitors. | My thinking is starting to slide towards the Axial insertion of the component in relationship to the smaller dia. of the lead. What do ya think?

reply »

reflow oven profiler

SMT Machines