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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


John Eramo

#11374

vibration during solder reflow | 21 May, 1999

Has anyone had any experience or data using vibration during the reflow process. We introduced a vibration device attached to the fixed rail on a Vitronics reflow oven. The reason was to prevent skewing on large PLCC devices. The process worked very well. I'm looking for comments.

Thank you

John Eramo 915-780-5521

reply »

#11375

Re: vibration during solder reflow | 21 May, 1999

| Has anyone had any experience or data using vibration during the reflow process. | We introduced a vibration device attached to the fixed rail on a Vitronics reflow oven. The reason was to prevent skewing on large PLCC devices. The process worked very well. | I'm looking for comments. | | Thank you | | John Eramo | 915-780-5521 | John: You make my head spin.

1 So how do you turn the vibration off after the solder begins to cool after liquidous to prevent producing a cold solder joint? 2 I want to have an oven with minimal vibration, you buy a solid oven and add vibration. Wierd. 3 Why don't you redesign your pads/stencil so the PLCCs don't skew?

Don't take this as an endoursement of your process, but where are your products used?

Dave F

reply »

JohnW

#11376

Re: vibration during solder reflow | 21 May, 1999

| | Has anyone had any experience or data using vibration during the reflow process. | | We introduced a vibration device attached to the fixed rail on a Vitronics reflow oven. The reason was to prevent skewing on large PLCC devices. The process worked very well. | | I'm looking for comments. | | | | Thank you | | | | John Eramo | | 915-780-5521 | | | John: You make my head spin. | | 1 So how do you turn the vibration off after the solder begins to cool after liquidous to prevent producing a cold solder joint? | 2 I want to have an oven with minimal vibration, you buy a solid oven and add vibration. Wierd. | 3 Why don't you redesign your pads/stencil so the PLCCs don't skew? | | Don't take this as an endoursement of your process, but where are your products used? | | Dave F | Vibrate the oven..????? sound's abit mad to me...I'm with Dave..sort the pad's on the product and / or the stencil... actually you may even want to check ur profile..ramp rates n all..I have this niggling feeling I seen that before but cant remember where...ummmmm

JohnW

reply »

Scott Cook

#11377

Re: vibration during solder reflow | 23 May, 1999

| Has anyone had any experience or data using vibration during the reflow process. | We introduced a vibration device attached to the fixed rail on a Vitronics reflow oven. The reason was to prevent skewing on large PLCC devices. The process worked very well. | I'm looking for comments. | | Thank you | | John Eramo | 915-780-5521 | Hey John, You don't say what pitch leads you are dealing with, but..... Did some testing along these lines with a vibratory feeder base attached to the edge rails of an oven back in the late 80's, early 90's. I was running 20 mil parts back then. It worked, but the other folks are right about cold joints. I never did perfect it. Now, be aware that my process rates at that time were 70 inches a minute, and I was using quartz IR tube technology in my ovens. Yes, that's right--65 to 70 IPM! The quartz tube lamp ovens were the only ones responsive enough to reflow the products at those rates; and we had to keep up with the placement at the front end. In those days, turning a board to toast was not uncommon at project startup.....

HOWEVER, Also worked with a company in the early 90's--think it was Yamaha or Panasonic. We were developing a volume 11 mil TAB process. We had to excise the TAB device out of a lead carrier, place it on the boards, and reflow. One of the issues at 11 mils is to keep the pads flat. In addition, back in the early 90's, we didn't have the process windows cranked down on printing like today. So, we tried deep gold, OSP, funky apertures, etc. Couldn't eliminate bridging. Ended up with eliminating paste deposition, and very TIGHT controls on plating / leveling / thickness. Gets fairly expensive. Today, I'd try SiPad for this process..... Anyway, the equipment was prototype. One of a kind; a lab machine someone cooked up in their mind. It had underside preheat, a wide area focused xenon beam (a custom aperture was developed for this device, and it's leadframe outline), a flux dispenser, and a vibrating table. As I remember it, we dispensed flux along the length of the pads (a run perpendicular to the leads), placed the TAB device down directly on the pads / flux, and as the xenon beam fired up, the table vibrated a bit at a pre-determined frequency (can't remember what that was....)and time interval. VERY tricky process, but it worked! We eliminated bridging. Key point here is that we had the PLACEMENT down. We weren't fighting skewing; just bridging. We never bought the machine, because the job went away (SOJ's replaced the TAB devices; it was a SIMM type product--but with LOTS of memory). That process was a nightmare, because you had to tightly define and understand the Xenon reflow parameters, and then program the vibration based upon that information, and turn off the vibration before you turned the Xenon lamp off.

Overall, I don't think the vibration idea is a good one. I'm with the other guys; tighten up the print windows......

Scott Cook

reply »

#11378

Re: vibration during solder reflow | 23 May, 1999

| Has anyone had any experience or data using vibration during the reflow process. | We introduced a vibration device attached to the fixed rail on a Vitronics reflow oven. The reason was to prevent skewing on large PLCC devices. The process worked very well. | I'm looking for comments. | | Thank you | | John Eramo | 915-780-5521 | John

So, is the PLCC skewed going into the oven? Or is the oven causing the skewing? I have never heard of a reflow oven causing skewing, unless the board is warping. I hate to state the obvious but if the parts are not on pad going into the oven then you should concentrate your efforts at placement or board handling.

My 2 cents

Mike

reply »

john thorup

#11379

Re: vibration during solder reflow | 24 May, 1999

| | | Has anyone had any experience or data using vibration during the reflow process. | | | We introduced a vibration device attached to the fixed rail on a Vitronics reflow oven. The reason was to prevent skewing on large PLCC devices. The process worked very well. | | | I'm looking for comments. | | | | | | Thank you | | | | | | John Eramo | | | 915-780-5521 | | | | | John: You make my head spin. | | | | 1 So how do you turn the vibration off after the solder begins to cool after liquidous to prevent producing a cold solder joint? | | 2 I want to have an oven with minimal vibration, you buy a solid oven and add vibration. Wierd. | | 3 Why don't you redesign your pads/stencil so the PLCCs don't skew? | | | | Don't take this as an endoursement of your process, but where are your products used? | | | | Dave F | | | Vibrate the oven..????? sound's abit mad to me...I'm with Dave..sort the pad's on the product and / or the stencil... | actually you may even want to check ur profile..ramp rates n all..I have this niggling feeling I seen that before but cant remember where...ummmmm | | JohnW

This vibrating idea could work, sort of like the rework station suppliers that suggest that you tap the board during liquidus to center the the component. But... the vibration would have to be just the right strength, just the right duration and applied just at the right time. It would also limit you to 1 board in the oven at a time -with horrible takt times. | do agree with the other guys - find and fix the root cause of your problem - don't bandaid the oven. You will gain much more in the long run. If you're sure that the components are properly placed when entering the oven... What about a vibration you don't know about like your chain/belt momentarily seizing or a bad bearing. Vibration external to the oven. Check pad shape and solder volume. Check the solderability of your pads and components - if it doesn't wet it wont pull. How large a skew are we talking about? Does it happen to every board. Have you personally verified that they are properly placed going in? This shouldn't be too hard to bring to closure - good luck

reply »

Ricardo Lopes

#11380

Re: vibration during solder reflow | 25 May, 1999

| | Has anyone had any experience or data using vibration during the reflow process. | | We introduced a vibration device attached to the fixed rail on a Vitronics reflow oven. The reason was to prevent skewing on large PLCC devices. The process worked very well. | | I'm looking for comments. | | | | Thank you | | | | John Eramo | | 915-780-5521

Hi John,

| John | | So, is the PLCC skewed going into the oven? Or is the oven causing the skewing? I have never heard of a reflow oven causing skewing, unless the board is warping. I hate to state the obvious but if the parts are not on pad going into the oven then you should concentrate your efforts at placement or board handling. | | My 2 cents | | Mike

I agree with our friend Mike but there is one more point to take a look. Board transfering from previous stage to oven.

Regards , Ricardo. | |

reply »

reflow oven profiler

Reflow Oven