Hello Frank.
Yes, in my experience, many materials most certainly do effect audio signals.
The fun is in the mixing and matching.
Dan.
How are we defining materials, and where do they make a difference, it is such an all encompassing statement that it is somewhat irrelevant. Without references to what material, where it is used and what real effect it has on the signal and what are the physics causing this effect it just hand waving.
I don't suppose anyone has a link to any real evidence that solder resist changes the sound.
Ah, thanks.
The problems I see with that are:
1. the non conductive epoxy used to hold the parts in place will define the solder thickness between the part and the board. If the parts or board have very little thickness in solder, the part can end up too close to the board. This increases the shear forces through temp cycling and can pop parts if the board is flexed. A minimal thickness of solder is needed to reduce von mises.
2. Flux introduction where it counts is more difficult, as a mounted part will hide the desired region from a spray.
3. The wave may not scrub well between the part and the board.
4. Preheat of the bottom comps poses an interesting problem. Caps that are too large will be subject to some hard thermal shocks.
I would not have wanted to be the process engineer trying to make that type of board reliable, especially if it requires military screening.
I certainly agree with the ROHS higher temps, it only makes matters worse, even after popcorning is alleviated.
jn
There are patterns in the noise, grasshopper.So what you are saying master is when I can understand how materials affect sound, but cannot be measured I can leave the temple
.Dan.
Military boards components can only go through a number of heat cycles, a ball ache when you have to re-ball your BGA's.
Double sided placement doesn't always require gluing (in fact very rarely) as most modern re-flow ovens have good top and bottom temperature zones control.
Very few modern SMD components are suitable or can withstand the thermal shock of wave soldering, and thermal shock is the killer. Same with tombstoning of components, if it happens then pre-heat is incorrect and there is thermal shock going on.
A lot of PTH components can be soldered using the pin in paste (intrusive reflow) method of assembly.
http://www.smartgroup.org/wp-content/uploads/PinInHoleReflow.pdf
Personally I have avoided wave soldering SMD components, I have never been happy with the results or the fact that the device goes through such a thermal shock, and SMD MLCC caps and similar components tend to get damaged.
Von mises are not as problematic today as they were 15+ years ago when there were quite a few ceramic devices, and the x and y CTEs of FR4 were worse (then 130TG was the norm today 170is is more the norm). High pin devices such as BGAs and LGAs use FR4 interposters so the CTEs match otherwise there would be trouble.
Process control and SMD equipement is much better these days and temperature profiles are better controlled and understood for reflow ovens, its a pity though that vapour phase never realy got anywhere (to many nasty chemicals), the first reflow system I played with was vapour phase, it had many advantages over reflow in them days (1986ish). Control is so good these days you can do mixed copper weight boards (2-4oz on the same board).
Double sided placement doesn't always require gluing (in fact very rarely) as most modern re-flow ovens have good top and bottom temperature zones control.
Very few modern SMD components are suitable or can withstand the thermal shock of wave soldering, and thermal shock is the killer. Same with tombstoning of components, if it happens then pre-heat is incorrect and there is thermal shock going on.
A lot of PTH components can be soldered using the pin in paste (intrusive reflow) method of assembly.
http://www.smartgroup.org/wp-content/uploads/PinInHoleReflow.pdf
Personally I have avoided wave soldering SMD components, I have never been happy with the results or the fact that the device goes through such a thermal shock, and SMD MLCC caps and similar components tend to get damaged.
Von mises are not as problematic today as they were 15+ years ago when there were quite a few ceramic devices, and the x and y CTEs of FR4 were worse (then 130TG was the norm today 170is is more the norm). High pin devices such as BGAs and LGAs use FR4 interposters so the CTEs match otherwise there would be trouble.
Process control and SMD equipement is much better these days and temperature profiles are better controlled and understood for reflow ovens, its a pity though that vapour phase never realy got anywhere (to many nasty chemicals), the first reflow system I played with was vapour phase, it had many advantages over reflow in them days (1986ish). Control is so good these days you can do mixed copper weight boards (2-4oz on the same board).
Hi,
Did any of you actually ever used, listened to or, god forbid, know, a mercury cable?
These did exist but were of course "verboten" in "Das dritte Reich", jawohl.
Dodo,
Frank there is a room temp mercury free liquid metal, galinstan. Our own KBK sells cables with some similar formulation AFAIK.
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There are patterns in the noise, grasshopper.
Dan.
Seems to me that 'noise' pretty much sums up your contribution to this thread so far.
I'm lucky, I never worked bga's.
MLCC's are a PITA, they are so sensitive to edge handling, and many operators don't understand. Saw lots of blow ups on those.
Vapor phase was soooo neat. Made a mini one using a 2 liter beaker, hotplate, and a copper cooling coil at top. Used 215 flourinert, but man was that stuff expensive.
Used it to step solder, tin silver first, then tin/lead.
jn
Its a long time ago and my memory is a bit dim (I probably have papers somewhere, I collect this sort of stuff regarding PCB design and assembly) but due to the way the heat was transferred with vapour phase the components were not subjected to thermal shock and it was quite gentle, compared to the heat curtains that passed as IR reflow ovens (shading etc!!!). The fumes were fun, I collapsed once due to the fumes when cleaning the machine out, had the worse headache for hours after, next time we let it cool down for hours, emptied the fluid and left it a day for the vapour to dissipate, the good old days before all the legislation.
Since the Toyota fun and games with tin whiskers etc, a lot of automotive where you have MLCC caps you have to double each cap up and have them positioned 90 degrees to each other -to avoid shorts across supplies due to the caps breaking due to PCB flexing or shock, as there failure for these devices is presumed to be a short, boy it makes doing these layouts fun!
You can now get your BGAs laser reballed:
BGA Components Reballing:Safest BGA Reballing|BGA Repair - Retronix Ltd
Not the cheapest, last time I used it it was 2.3p a ball (UK pence) 3000+ balls on a PCB soon mounts up, but it negates a thermal cycle for the device as it is not reflowed.
Since the Toyota fun and games with tin whiskers etc, a lot of automotive where you have MLCC caps you have to double each cap up and have them positioned 90 degrees to each other -to avoid shorts across supplies due to the caps breaking due to PCB flexing or shock, as there failure for these devices is presumed to be a short, boy it makes doing these layouts fun!
You can now get your BGAs laser reballed:
BGA Components Reballing:Safest BGA Reballing|BGA Repair - Retronix Ltd
Not the cheapest, last time I used it it was 2.3p a ball (UK pence) 3000+ balls on a PCB soon mounts up, but it negates a thermal cycle for the device as it is not reflowed.
Hi,
Interesting. I'll look into that further.
Thanks, Scott.
I'm to blame for that as well, I'm afraid.
Not sure if it can't be measured but I suspect it will take spectral analysis.
Problem with that stuff is that no one really seems to be doing any real research in that particular field.
Ciao,
Interesting. I'll look into that further.
Thanks, Scott.
I'm to blame for that as well, I'm afraid.
Not sure if it can't be measured but I suspect it will take spectral analysis.
Problem with that stuff is that no one really seems to be doing any real research in that particular field.
Ciao,
I am currently setting up T&M gear to do exactly that.Not sure if it can't be measured but I suspect it will take spectral analysis.
Problem with that stuff is that no one really seems to be doing any real research in that particular field.
Ciao,
My previous posts are entirely serious.
Dan.
Hi,
Interesting. I'll look into that further.
Thanks, Scott.
I'm to blame for that as well, I'm afraid.
Not sure if it can't be measured but I suspect it will take spectral analysis.
Problem with that stuff is that no one really seems to be doing any real research in that particular field.
Ciao,
Regarding Solder resist, in an earlier post I did say we do factor it into simulations for very high speed digital/some RF, but only really for timing budgets and electrical length calculations. As to audibility of solder mask, nah I think this one can be added to the myth section
I "support any weird esoteric claim", do I? Interesting how people take major leaps of imagination - what I do believe in is that everything has the potential to affect the situation in some manner; the argument then devolves into whether this is audible at times, to some people. If one is content to accept the 'proofs' by Authority Figures that Some Things Are Important and Other Things Aren't then one's audio life is greatly simplified - no matter what you actually hear when you listen, you know which way to hop, to remain with the In Crowd ...
Solder masks, solder whatevers, audible? I wouldn't have a clue - plenty of other things to worry about ...
Solder masks, solder whatevers, audible? I wouldn't have a clue - plenty of other things to worry about ...
Is that really how you believe conventional fact-based engineering and science works? If so, it is not surprising that you object to it but it makes me wonder if you were asleep during science lessons at school? On the contrary, it is pseudo-science and crank 'science' (and some audiophilia) which proceeds by bowing to Authority Figures; true science (and thus engineering too) follows the evidence and formulates explanations. These explanations cannot be simply discarded because someone does not like them or does not understand them. Audio electronics cannot have its own private set of explanations, being as it is merely a low frequency relatively uncritical branch of electronics (i.e. applied physics).fas42 said:
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