[tomb]

Quote:

I used a toaster oven and did the top side reflow-style, it came out AWESOME!
I have a bridge or two, but everything is centered and straight (except U10, but it's not too bad).
 
I'm going to touch it up tomorrow and then get started on the bottom.
 
Using solder paste and the oven, the top took under 1hr to fully populate.

That's great!
 
Heh - the bottom is a piece of cake after the top.  Just go slowly and carefully.  The SMD caps are not hard to solder, but there are a heck of a lot of 'em on that back side and you wouldn't want to get them mixed up.

  Soldering the opamp will seem like soldering through-hole after the PCM and TPS chips.

 

[scootsit]

Quote:

Quote:

I used a toaster oven and did the top side reflow-style, it came out AWESOME!
I have a bridge or two, but everything is centered and straight (except U10, but it's not too bad).
 
I'm going to touch it up tomorrow and then get started on the bottom.
 
Using solder paste and the oven, the top took under 1hr to fully populate.

That's great!
 
Heh - the bottom is a piece of cake after the top.  Just go slowly and carefully.  The SMD caps are not hard to solder, but there are a heck of a lot of 'em on that back side and you wouldn't want to get them mixed up.

  Soldering the opamp will seem like soldering through-hole after the PCM and TPS chips.

I really love the solder paste, I may actually use it with the iron. It flows really nicely. We'll see, I'm going to experiment a bit. I guess I can do the back by hand, but I'd prefer to bake it - I just don't think that will work.

 

[Lefuneste]

Another interesting use of toasting ovens!! I already used it to heat treat knife blades after quenching!!
Believe it or not, it can ALSO be used to toast bread!! What an invention this is!!

 

[KimLaroux]

Quote:

I really love the solder paste, I may actually use it with the iron. It flows really nicely. We'll see, I'm going to experiment a bit. I guess I can do the back by hand, but I'd prefer to bake it - I just don't think that will work.

 
Would the components on the top side (flipped over) not just fall off once the solder melts?
 
Unless of course you own a close-field anti-gravity generator. 

 

[tomb]

Quote:

 
Would the components on the top side (flipped over) not just fall off once the solder melts?
 
Unless of course you own a close-field anti-gravity generator. 

According to scootsit, the re-melt temp is much higher, so it may not be as silly as it sounds.

 

[scootsit]

Quote:

Quote:

I really love the solder paste, I may actually use it with the iron. It flows really nicely. We'll see, I'm going to experiment a bit. I guess I can do the back by hand, but I'd prefer to bake it - I just don't think that will work.

 
Would the components on the top side (flipped over) not just fall off once the solder melts?
 
Unless of course you own a close-field anti-gravity generator. 

Virgin solder melts about 200F cooler than does already melted solder. I'm thinking it's because of the flux. If you hit the reflow temp, then it probably would, though the surface tension may actually keep it in place.

 

[KimLaroux]

Now that's interesting... I didn't know melting temperatures changed like that. Or that flux affected it. I thought the only thing flux did was clean surfaces to help solder flow on it.
 
I'll have to remember this one. Thanks for the tips. 

 

[scootsit]

Quote:

Now that's interesting... I didn't know melting temperatures changed like that. Or that flux affected it. I thought the only thing flux did was clean surfaces to help solder flow on it.
 
I'll have to remember this one. Thanks for the tips. 

It doesn't really make sense, and someone more in the know than I may have to clear that up. But, I'm assuming it's about surface area. Little metal filings will melt before solid globs will. So, I'm sort of assuming the melting point is more or less the same, but by suspending it in a fluid with a boiling point exactly at the melting point of the metal, you create a homogenized high-surface-area fluid ready to melt at the drop of a hat. A big glob needs to get much hotter to maintain a consistent temperature near the melting point, especially since there is no flow.

 

[scootsit]

Alternatively, and now that I think of it, more likely - the melting point of each metal (which is ground into a dust) could be one thing (low), but the melting point of the homogenized alloy could be a bit higher.

 

[scootsit]

My OPA2835 doesn't have a dot on the top, instead it has a line across one end. Is the line on the pin 1/pin 8 end?

 

[tomb]

This is mentioned in the Build Thread and in the construction pages on the pupDAC website.  The line is on the same side as if there was a dot.  If you think about it, the dot is no different than a line, unless you're talking a four-cornered chip like the PCM2706/7.

 

[scootsit]

Quote:

This is mentioned in the Build Thread and in the construction pages on the pupDAC website.  The line is on the same side as if there was a dot.  If you think about it, the dot is no different than a line, unless you're talking a four-cornered chip like the PCM2706/7.

Great, thanks! I figured as much and just built it anyway. All the SMT stuff is done, just scrubbed the hell out of it with alcohol. It's weird that the OPA2835 can't even be in humid environments before being soldered, but after it can be submerged. I guess something would crack with the heat. Anyway, I used the solder paste and basically stuck each piece in it, then used the iron to heat it. The result is that you can have the iron in one hand and the tweezers in the other, no need to hold any solder, so you can make sure each piece lines up perfectly.

 

[Lefuneste]

Hi guys, just a quick update photo as I've received the oscons for the decoupling of the DAC chip (47uF, 16V). Here's the result once mounted in place of the ELNA SILMIC II 22uF 25V I had put in place of the already excellent Panasonic FM (original kit capacitor). BTW unsoldering was quite tedious in order to fully respect the vias. This really requires a little experience, so be carefull if you ever have to unsolder through-holes components on this delicate PCB. I also had to clean each hole of solder before putting new caps with a vaccum pump.
 
Sounding with Oscons appears improved on clarity and depth. Rendering seems to have slightly increased in purity. The most interesting effect is the staging and space sensation. Of course at this level of native quality, it is all very subjective!! Anyway, good luck with your projects!!
 

 

[tomb]

Quote:

Great, thanks! I figured as much and just built it anyway. All the SMT stuff is done, just scrubbed the hell out of it with alcohol. It's weird that the OPA2835 can't even be in humid environments before being soldered, but after it can be submerged. I guess something would crack with the heat. Anyway, I used the solder paste and basically stuck each piece in it, then used the iron to heat it. The result is that you can have the iron in one hand and the tweezers in the other, no need to hold any solder, so you can make sure each piece lines up perfectly.

Actually, this has been the recommended method since day 1 - without solder paste.  You apply the solder to a single pad, first.  The you re-melt it with the iron in one hand and place the part with tweezers in the other hand.  That's fundamental with manual SMD soldering.

 

[tomb]

Quote:

Hi guys, just a quick update photo as I've received the oscons for the decoupling of the DAC chip (47uF, 16V). Here's the result once mounted in place of the ELNA SILMIC II 22uF 25V I had put in place of the already excellent Panasonic FM (original kit capacitor). BTW unsoldering was quite tedious in order to fully respect the vias. This really requires a little experience, so be carefull if you ever have to unsolder through-holes components on this delicate PCB. I also had to clean each hole of solder before putting new caps with a vaccum pump.
 
Sounding with Oscons appears improved on clarity and depth. Rendering seems to have slightly increased in purity. The most interesting effect is the staging and space sensation. Of course at this level of native quality, it is all very subjective!! Anyway, good luck with your projects!!
 

Great!  As with any DIY project, it's the tweaking that often makes it fun!!