Recomended footprint is incorrect? (diode footprint)

[Flyback]

Hello,
Do you agree that the recommended footprint on page 4 of the SBRT25U80SLP diode datasheet is incorrect?
The long sides of the SBRT25U80 diode have metal protrusions sticking out of them, which emenate from the large main pad of the SBRT25U80 diode.
However, the recommended footprint does not offer a metal pad for these bits of protrusion. Worse still, if one were to use the recommended footprint shown, then there would be solder resist under those “lateral protrusions”. This solder resist would partially melt during surface mount flow soldering, and would “stick” to the lateral protrusions, and thus prevent the component from “settling” onto its pads….thus meaning improper soldering.
Do you agree, the shown recommended footprint needs to be extended to take into account the lateral protrusions to the main pad of the SBRT25U80SLP diode?
Datasheet : SBRT25U80SLP diode
**broken link removed**

 

[alec_t]

The suggested pad layout is one thing; the resist layout (not specified) is another. Personally, unless the pcb area were needed for other traces, I'd make the pad much wider than the diode dimension 'D'.

 

[Flyback]

thanks, but as you know, its unwise to make the pads of these components wider than recommended, because it doesn't help with the settling of the component onto the pad....also, are you saying that we should re-do the solder resist (solder mask layer) so that the solder resist doesn't cover these protrusions?

 

[ronsimpson]

I think the recommended pad is OK.
I would have made it different but....
I think it is OK for the protrusion will sit on top of the solder mask just as the black body sits on top of the solder mask. The solder thickness will be more than the solder mask!

 

[alec_t]

are you saying that we should re-do the solder resist (solder mask layer) so that the solder resist doesn't cover these protrusions?

Only if you are sure that "This solder resist would partially melt during surface mount flow soldering, and would “stick” to the lateral protrusions, and thus prevent the component from “settling” onto its pads….thus meaning improper soldering." But, as per Ron in post #4, I think that's unlikely.

 

[JonSea]

The whole purpose of soldermask is to confine solder to the desired areas and not allow bridging between pads. If the soldermask is melting, maybe your soldering temperature is too high.

 

[Flyback]

solder mask does what you say, but if you put molten solder on it, it will melt and go soft....just get your solder iron and push it on to solder resist on a pcb...it will melt

 

[ronsimpson]

solder mask does what you say, but if you put molten solder on it, it will melt and go soft....just get your solder iron and push it on to solder resist on a pcb...it will telt

When I solder the entire board in the oven, I have good control of the temperature. I don't think I am damaging the solder mask/silk screen.