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WAVE SOLDERING 0603 CHIP RESISTOR ARRAYS

Robert Hutton-Squire

#4482

WAVE SOLDERING 0603 CHIP RESISTOR ARRAYS | 10 April, 2000

Suggestions please...

I have to place a number of 1206 chip resistor arrays on the bottom side of my PCB for wave soldering. The device consists of 4 x 0603 resistors in a 1206 package. The device is available with either concave or convex terminations - which would you recommend for wave soldering and should I orient the devices perpendicular or parallel to the wave?

Thanks, - Robert

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#4483

Re: WAVE SOLDERING 0603 CHIP RESISTOR ARRAYS | 10 April, 2000

Rob: What was driving the uBGA bridging?

On your arrays: * I doubt that your supplier would be pleased that you are wave soldering these pups. If you insist, present leads to the wave on opposite sides of the package at the same time. Is this an 8 (4 each on opposite sides) or 10 lead (4 each on opposite sides and one on each end)? * Regardless if you're waving or reflowing, go with the concave.

Good luck Dave F

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RDR

#4484

Re: WAVE SOLDERING 0603 CHIP RESISTOR ARRAYS | 11 April, 2000

Quick question for Dave, Out of curiosity, why concave? I ask because we are soldering RNETs that come in either style and have not payed much attention to this.

Russ

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#4485

Re: WAVE SOLDERING 0603 CHIP RESISTOR ARRAYS | 11 April, 2000

Russ: You�re correct. I should have explained our reasons for preferring concave over convex better. First, we use both also ... we just prefer concave because they: * Don�t bridge any where near as easily. * Self-center better. * Seem to have more balanced wetting forces (which may be saying the same thing as the previous tick).

The plating of the termination areas are not defined well on the actual convex part. If you look at their drawings, they show the terminal as narrow strip centered on the convex portion for each resistor. When you look at the part, the actual terminal runs into that area between the convex termination for each resistor ... and that�s what produces the shorts and the unbalanced wetting forces.

At one time, the Philips site had really neat photos of what I babbling about, but I just checked and half of their ap notes won't download.

Good luck Dave F

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RDR

#4486

Re: WAVE SOLDERING 0603 CHIP RESISTOR ARRAYS | 12 April, 2000

Thanks, Dave appreciate the info. One of my trains of thought was leading to the convex because I thought that having the "bump" would allow for easier wave soldering? I did look at some data we had and did find you to be correct, the concave have a higher yield at SMT and I am not sure about wave yet. I cannot find the data that I need.

Thanks again

Russ

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#4487

Re: WAVE SOLDERING 0603 CHIP RESISTOR ARRAYS | 12 April, 2000

Russ: That�s a pretty stand-up postin� bud. It�s neat that you can root-out that dirt. We couldn�t dig-up that stuff, if they threatened to shoot the dog.

You could be correct about using convex for waving. We don�t wave RNET as Philips suggests in several application notes ("8-Resistor Bussed Network" for one) as follows: � Note that this product will be easily damaged by rapid heating, rapid cooling, or local heating. � Do not subject the product to thermal shock by the use of soldering temperatures greater than 100�C. We recommend the use of preheating and annealing (gradual cooling) stages during the soldering cycle. � Wave soldering of this product is not recommended since this can lead to the formation of solder bridging due to the narrow 0.8 mm pitch of the product.

Well, at least the second bullet is a bit wacked, because Philips, in the very same ap note, shows a reflow profile with a peak temperature of 220�C. And 10 second time at 215�C

So, please tell us more about wavin� RNET. What profile, flux, pads shape etc. do you use? What do know about LT component reliability?

Thanks Dave F

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reflow oven profiler