Wave soldering small SMD like SOT363 and smaller

[juicedry]

I am exploring the possibility of wave soldering small SMD like SOT363/SOT563. Currently we do reflow on such small footprint components.

All the small components will be leaded pins, so from my point-of-view, are "suitable" for wave soldering. Have you wave soldered such small SMD? If so, what are the challenges?

 

[KlausST]

Hi,

first i thougt it should be possible.
* You need to glue the device on the solder side.
* you should take care of solder direction
* you need larger smd pads
* eventually you need some additional solder catch pads

****
But then i googled "sot363 wave soldering"

--> www.nxp.com/documents/wave_soldering/sot363_fw.pdf
and other good documents on this.

Also there will be IPC / IEC documents.

I wonder why you didn´t find this

Klaus

 

[juicedry]

Thank you for the quick reply. I had already found the NXP SOT363 wave soldering footprint and I've been studying the IPC-7351 spec. Now I understand that the SOT563 (otherwise called the SOT666) is not recommended for wave soldering.

My concern is that these small packages maybe more likely to bridge or even just float away during wave soldering! Has anyone experienced this, especially in mass-production with many boards.

 

[KlausST]

Hi,

these small packages maybe more likely to bridge or even just float away during wave soldering!

I don´t see any problem with an adapted wave soldering process.

* Glue to avoid float away.
* eventual extra pads to avoid shorts.

Ask your assembling (and soldering) company. They usually can give you further assitance.

Klaus

 

[marce]

I have never been a fan of wave soldering SMD parts, reflow is much better solution. Wave soldering for SMD components was hard enough to control when they were much larger (late 80's) than they are now. Personally I would never recommend wave soldering for any SMD assembly, to many down sides.

 

[KlausST]

Hi,

I have never been a fan of wave soldering SMD parts

me too. But it worked.

I don´t know how many problems the Pb-free solder causes.

Klaus

 

[juicedry]

I agree with the preference being reflow. I am just trying to utilise the wave solder equipment.

me too. But it worked.

Now when you said it worked, did you have smaller than SOT23 packages with narrow pitch between multiple pins? Did it yield consistently well?

 

[Mattylad]

What I do not see in the OPs post is "why" wave solder them?

Just because they may be suitable to be wave soldered does not mean that it is the best way of soldering them.

What is the driving force behind the choice to wave solder them instead of reflow soldering them?

 

[juicedry]

I trying to use the existing wave solder equipment as it is under-utilised. The existing SMD devices are SOT23, DPAK etc. Now the new projects are with smaller than SOT23 packages with narrow pitch between multiple pins. I agree that the preference would be reflow; however, I am just exploring the wave soldering as an option.

Of course it would Pb-free solder, so any concerns relating to that in wave soldering would be useful.

 

[Mattylad]

IMO Wave solder equipment will be under utilized now, because PTH components are far less common.
However SMT is far better soldered using reflow, it is cheaper, quicker and easier to do. Pad dimensions are often made larger for wave, solder thief pads are used etc decreasing the amount of available space for components.

What you could do is try paste in pad so that your PTH components are soldered by the reflow oven at the same time as the SMT components.

 

[marce]

Thermal shock to the components, that has always been my concern and the main reason why I do not promote it.
Cannot control the amount of solder for the joint, increased production problems such as shorts etc.