There is no single "right" way to solder these boards. I'll share what I have done, and a couple of things I wish I had done differently.
For the smaller leaded components, such as the 1/2W resistors, small signal transistors and small diodes, most of the connections can be made with a bit cooler iron and smaller tip. My tip is about 2mm, and set my temperature to 250C. I solder everything from the back first, using the leads to hold the part in place when I turn the board over. There are a number of connections that are not going to be easy to solder at that temperature. Basically anything on a ground plane and much of the power stage. For most of those, I'll turn the iron up to 280C. The screw terminals required about 315C to make progress.
I should have changed the tip for the larger connections, probably to a 4 or 5mm tip. A trick I use for the wide copper connections that worked well is to lay the iron down so that a large part of the tip contacts the trace without touching the lead. Then, once the solder starts to melt on the exposed trace, I move to the component lead and feed solder from the opposite side of the lead. When the flow through occurs, you will notice that the solder surface suddenly becomes turbulent as the solder wicks through the hole. It's subtle, but look for small ripples on what was a perfectly shiny surface. Many of the holes are large enough that fine solder can be fed into the hole before it melts to help ensure that the via is completely filled. Watch for large blob of solder forming either on the component lead or iron. That indicates that the trace is not yet hot enough.
I'm getting old and my eyesight is not that good anymore, so I use my surface mount microscope for most soldering. Otherwise, I would have to take my glasses off and stick my face a couple of inches away from the board, which really seems like a bad idea with the forest of leads and occasional solder sputters.
Another thing I have done is to use the hot air station to generally heat up the planes to about 150C. That can make a big difference on large ground planes. Wave soldering lines pre-heat the board before the solder wave is used to complete the job. I'm not generally an advocate of using much hotter irons, mainly because the tips oxidize rapidly above about 240. 63/37 solder melts at 183C. The non-Bi lead-free alloys generally melt around 220C.
As for soldering on the top-side, that is just for a few touch-ups. If you turn the board over and notice that there are gaps between the lead and the top of the hole, then a touch-up is in order, but once the holes is completely full and the meniscus on the lead is concave, then there is no benefit in more solder.. Usually one side or the other is most closely connected to the wide copper. What is needed is mostly more heat rather than higher temperature. It's true that higher temperatures provide more heat, and there is nothing wrong with the hit and run technique if you are careful. Larger tips also provide more heat, at least temporarily. You are doing fine, and it will get easier with experience. Getting flux off the top side with through-hole parts is not easy, so avoiding it in the first place is helpful.
For the smaller leaded components, such as the 1/2W resistors, small signal transistors and small diodes, most of the connections can be made with a bit cooler iron and smaller tip. My tip is about 2mm, and set my temperature to 250C. I solder everything from the back first, using the leads to hold the part in place when I turn the board over. There are a number of connections that are not going to be easy to solder at that temperature. Basically anything on a ground plane and much of the power stage. For most of those, I'll turn the iron up to 280C. The screw terminals required about 315C to make progress.
I should have changed the tip for the larger connections, probably to a 4 or 5mm tip. A trick I use for the wide copper connections that worked well is to lay the iron down so that a large part of the tip contacts the trace without touching the lead. Then, once the solder starts to melt on the exposed trace, I move to the component lead and feed solder from the opposite side of the lead. When the flow through occurs, you will notice that the solder surface suddenly becomes turbulent as the solder wicks through the hole. It's subtle, but look for small ripples on what was a perfectly shiny surface. Many of the holes are large enough that fine solder can be fed into the hole before it melts to help ensure that the via is completely filled. Watch for large blob of solder forming either on the component lead or iron. That indicates that the trace is not yet hot enough.
I'm getting old and my eyesight is not that good anymore, so I use my surface mount microscope for most soldering. Otherwise, I would have to take my glasses off and stick my face a couple of inches away from the board, which really seems like a bad idea with the forest of leads and occasional solder sputters.
Another thing I have done is to use the hot air station to generally heat up the planes to about 150C. That can make a big difference on large ground planes. Wave soldering lines pre-heat the board before the solder wave is used to complete the job. I'm not generally an advocate of using much hotter irons, mainly because the tips oxidize rapidly above about 240. 63/37 solder melts at 183C. The non-Bi lead-free alloys generally melt around 220C.
As for soldering on the top-side, that is just for a few touch-ups. If you turn the board over and notice that there are gaps between the lead and the top of the hole, then a touch-up is in order, but once the holes is completely full and the meniscus on the lead is concave, then there is no benefit in more solder.. Usually one side or the other is most closely connected to the wide copper. What is needed is mostly more heat rather than higher temperature. It's true that higher temperatures provide more heat, and there is nothing wrong with the hit and run technique if you are careful. Larger tips also provide more heat, at least temporarily. You are doing fine, and it will get easier with experience. Getting flux off the top side with through-hole parts is not easy, so avoiding it in the first place is helpful.
I’m curious- which tube pre? I had a CJ for decades, but the best I’ve heard recently is new Audio Research.
Not going to argue with that, but I was planning on dunking the boards in a shallow IPA bath. I can't imagine that any of my resistors' coating will be harmed by a brief bit of IPA, but interested in hearing any recommendations not to do so.
@ostripper did you try bootstrap pre-driver in 3EF output?
I simulated it, it increase VAS linearity and increase PSRR. Several friends of mine are success implemented my simulation.
I simulated it, it increase VAS linearity and increase PSRR. Several friends of mine are success implemented my simulation.
@stuartmp, your boards look absolutely spotless on your photo album. What method did you use to clean ?
Here is my process.
If I am cleaning the entire board, I first clean with MG Chem Flux Remover, then MG Chem Super Wash, then Aerosol based Isopropyl then dry.
Spot cleaning I use a tooth brush dipped in lacquer thinner to clean flux, then another tooth brush dipped in 99% Isopropyl.
If I am cleaning the entire board, I first clean with MG Chem Flux Remover, then MG Chem Super Wash, then Aerosol based Isopropyl then dry.
Spot cleaning I use a tooth brush dipped in lacquer thinner to clean flux, then another tooth brush dipped in 99% Isopropyl.
@fireanimal
Thanks for your input. I’ll look into MG Chemical Super Wash.
My method is also different but works and without risk for the past decade.
I use Chemtronics Flux Off “Plus”, while using an ESD rated brush to remove the worst residues, then immediately pour distilled water from a 1 gallon jug (at room temperature), shake off the excess liquid from the pcb, then place this ‘wet’ PCB on a Lazy Susan lined with KimWipes while running hot air at it and spinning the Lazy Susan. Finally a visual inspection with a loupe or Yoctosun glasses, etc…
Lots of steps but kind of automated for me at this point. In fact, I do have a small motor coming to power the Lazy Susan so it spins automagically.
But I like your method more because it eliminates the risks associated with distilled H2O.
Best,
Anand.
Thanks for your input. I’ll look into MG Chemical Super Wash.
My method is also different but works and without risk for the past decade.
I use Chemtronics Flux Off “Plus”, while using an ESD rated brush to remove the worst residues, then immediately pour distilled water from a 1 gallon jug (at room temperature), shake off the excess liquid from the pcb, then place this ‘wet’ PCB on a Lazy Susan lined with KimWipes while running hot air at it and spinning the Lazy Susan. Finally a visual inspection with a loupe or Yoctosun glasses, etc…
Lots of steps but kind of automated for me at this point. In fact, I do have a small motor coming to power the Lazy Susan so it spins automagically.
But I like your method more because it eliminates the risks associated with distilled H2O.
Best,
Anand.
Can't get the MG stuff here in the Netherlands. Probably a noob question but can you just spray all the components including elco's and semi's without limit so to say?...btw..I'm using this stuff.....and yes ..the way Stuarts boards look like was also my reference. Need a few more miles to reach that level
@sp33ls Most components tolerate IPA just fine. The problem is that a dunking in IPA will still require some mechanical action to get the flux off, since the common rosin core flux is not real soluble in IPA. Also, as soon as you open the IPA 99% it will absorb water vapor and soon become IPA70%, especially if it is in a tray for dipping. You might check the capacitor and pot data sheets to see if there are problems with some solvents.
@fireanimal has a good process, but it uses stuff that may not be available in all countries. Notice he uses the IPA for a final rinse and dry. He removes the flux with a formulated flux remover.
@fireanimal has a good process, but it uses stuff that may not be available in all countries. Notice he uses the IPA for a final rinse and dry. He removes the flux with a formulated flux remover.
I didn't mean to imply there is only one way. All my statements are in reference to what I do that works for me. That doesn't mean there aren't other ways to skin the cat.
It's all good... you gave him a much more thorough response and the hot air trick for larger planes is something I only just learned from one of the build group on the Wolverine. Likewise heating the entire board when working with SMD can really be helpful as well, but we digress.
Cleaning process is easy.
Do one side at a time and clean often. I think I did steps 1-4, 3 times for each board as I build them. With step 5 only necessary at then end.
1. I use a manual pump pack of 99% isopropyl alcohol. I spray it liberally over the surface to help to dissolve the flux.
2. Use a medium toothbrush and scrub the board in the x and y axis. Then apply more isopropyl alcohol and scrub with the toothbrush in a circular motion over the board.
3. Then apply more isopropyl alcohol so the flux and isopropyl alcohol are all mixed together. Now quickly before the isopropyl alcohol evaporates
stand the board up and spray it slowly left to right, top to bottom. The idea is to wash the isopropyl alcohol and flux off the board in one go.
4. Then let it sit and dry.
5. I then just go over the board with some more isopropyl alcohol and a cotton tip. I get a small container and pour some isopropyl alcohol in it. Then just dip the cotton tip in it and go over the entire board left to right, top to bottom. This will remove any last stubborn bits of flux and other impurities.
Hope that helps
Hi Guys.
I have spent the last few week working on a major update to the build guide.
I've attaching it to the first post of this thread and placed it in the Dropbox folder so I can keep it updated.
It may contain a few small errors but I have done my best for now.
I hope that you guys can try and follow it and let me know if you see any error or if anything is unclear so I can update it.
I have spent the last few week working on a major update to the build guide.
I've attaching it to the first post of this thread and placed it in the Dropbox folder so I can keep it updated.
It may contain a few small errors but I have done my best for now.
I hope that you guys can try and follow it and let me know if you see any error or if anything is unclear so I can update it.