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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


John

#11699

2512's To Wave or not to Wave???? | 27 April, 1999

Has anybody had experience wavesoldering 1 watt 2512 resistor packages?? I know it can be done, but are there reliability issues?

We are in the middle of a new product and the question was posed to me "Can we use 2512 1 watt resistors on the bottom side of the PCB? Some of the manufacturers were contacted. The responses were, "YES!!", "Absolutely", and "Are you kidding, no one wave solders 2512's." That left me a little uncomfortable....... I already suggested using two smaller parts in parallel, but that didn't go over too well. ....So if anyone does this regularly or has experience with these size parts, let me know what you think. Thanks!!

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JohnW

#11700

Re: 2512's To Wave or not to Wave???? | 27 April, 1999

| Has anybody had experience wavesoldering 1 watt 2512 resistor packages?? I know it can be done, but are there reliability issues? | | We are in the middle of a new product and the question was posed to me "Can we use 2512 1 watt resistors on the bottom side of the PCB? Some of the manufacturers were contacted. The responses were, "YES!!", "Absolutely", and "Are you kidding, no one wave solders 2512's." That left me a little uncomfortable....... | I already suggested using two smaller parts in parallel, but that didn't go over too well. | ....So if anyone does this regularly or has experience with these size parts, let me know what you think. Thanks!! | John,

been wave soldering these for a while with no problems, trick is to slightly enlarge the lad's a bit so there is no chance of shadowing either with the fluxer or the wave.

good luck

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Justin Medernach

#11701

Re: 2512's To Wave or not to Wave???? | 27 April, 1999

| Has anybody had experience wavesoldering 1 watt 2512 resistor packages?? I know it can be done, but are there reliability issues? | | We are in the middle of a new product and the question was posed to me "Can we use 2512 1 watt resistors on the bottom side of the PCB? Some of the manufacturers were contacted. The responses were, "YES!!", "Absolutely", and "Are you kidding, no one wave solders 2512's." That left me a little uncomfortable....... | I already suggested using two smaller parts in parallel, but that didn't go over too well. | ....So if anyone does this regularly or has experience with these size parts, let me know what you think. Thanks!!

too funny, I just had this issue come up this morning. You can wave the 2512s. You just have to watch out for shadowing components behind the 2512 but they will certainly hold on and take solder. The other thing is the cost of the part. The one watt part is about 72 cents. 4 quarter watt parts are 4 cents a piece. You do the math. Present that one to management and then see if it "doesn't go over too well."

Regards, Justin

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#11702

Re: 2512's To Wave or not to Wave???? | 27 April, 1999

| | Has anybody had experience wavesoldering 1 watt 2512 resistor packages?? I know it can be done, but are there reliability issues? | | | | We are in the middle of a new product and the question was posed to me "Can we use 2512 1 watt resistors on the bottom side of the PCB? Some of the manufacturers were contacted. The responses were, "YES!!", "Absolutely", and "Are you kidding, no one wave solders 2512's." That left me a little uncomfortable....... | | I already suggested using two smaller parts in parallel, but that didn't go over too well. | | ....So if anyone does this regularly or has experience with these size parts, let me know what you think. Thanks!! | | | John, | | been wave soldering these for a while with no problems, trick is to slightly enlarge the lad's a bit so there is no chance of shadowing either with the fluxer or the wave. | | good luck | My 2 cents:

Can you wave them? Yes. Do you want to wave them? Not if you can help it.

Depends on the process - got a good active chip wave? Good fluxes? Good adhesive and dispensing process?

Depends on the design - got good six-sided terminations on the component? Got a footprint for wave soldering with bigger lands than the reflow footprint that the vendor provided? Got shadowable parts out of the keepout zone? Got any room on the top side of the board for this ?

The taller or heavier the part, the more likely it will be knocked off the bottom of the board in the wave. It's got a lot of forces acting against it - the adhesive softens in preheat, gravity starts taking over and stressing the adhesive more by pulling the component away from the board, and then a wall of viscous, molten solder hits it in the side in about an eigth of a second.

Taller parts like tantalum caps have a higher center of gravity and get "pushed" off the board by the wave, and heavier parts like 2512's can be "dangling" off the board by a string of gooey glue (in microscopic terms) by the time they hit the wave.

So with the proper design and a good process, it's not a problem. If the assembly process isn't the most robust, however, I'd look for alternatives.

Chrys

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