While it's not possible to acquire Tantalum replacements for every single cap on the logic board, most caps can be replaced with tants. Any flavor of tants will do, SMD or dipped radial. You won't have to replace them every 15 years (or even every 30 years) like you will with electrolytics. But electrolytucs are cheaper and commonly found on most of our hobby parts boxes at home.
I've recapped one board with electrolytics and one with tants (yes, the boards function the same). I then used hot glue to secure the radial tants because the pads they solder onto can break off the board easily. (You won't have to do use hot glue if you use SMD tants.) By gluing radial caps down, there's no worry about breaking a trace by accident. And believe me, if you push a little too hard on a radial cap that's not glued, you will snap a pad clean off the logic board! This is an ever greater concern if you recap a board and then ship it to someone, because with too much external pressure on a non-glued cap, a trace could easily break. But of course, if you glue down electrolytics, then you will have to carefully cut through the clue a couple decades hence to replace them again. So this is why tants are a good choice for capacitor replacement because they will last as long as the logic board itself will (50 years? 80 years?).
The main thing you'll need in this replacement job is patience. If you have that, then you need the right tools. It's best if you have a tweezer soldering tip iron so you can apply heat to both sides of the existing SMD caps at once. It makes them easy to remove and it also lessens the liklihood you will break a trace (which often occurs if you desolder one side, force it up, and then desolder the other side). Of course, a tweezer tip is a bit uncommon, so most people just go the el-cheapo route. But you will need to use a continuity checker in the end to make sure no traces are broken. Otherwise you can bet on some unexplainable crashes and freezes when you're done.
It's really not all that hard to replace all the caps on an SE/30 logic board. But you have to be diligent and do the job completely and thoroughly. Don't have family members or kids around you when you start either. REPLACE EVERY CAP slowly and properly. Don't just replace 2 or 3 here and there because someone online said that would be enough. Replace them all. Why? Because they are old, leaking, and on their last legs (even if you cannot see evidence of leaking). And yes, I mean replace those two big caps as well, the ones with axial leads (you can use radial leg replacements if you want). Replace them all! Only then can you be 100% sure that your board is as good as new. Sure, sure, someone will come along and tell a happy story even though they didn't replace those axial caps. But those of you reading this need to do the job right and replace them all.
If after replacing all the caps the board still acts funny or won't work at all, there are other test and things you can try. But I must say this, I have one SE/30 board that is totally dead and cannot be resurrected, no matter what I try. It could be a bad chip, in which case you're better off buying a new board than to spend the months or years required to figure out the root problem. I've not been able to find the root problem on my dead board even though I have complete schematics and spent hours and hours on the problem! But not every board is like my dead board. Most can be restored to new operating condition with a good cap job.
Hope this helps.
