*RC3-Music*
Herald: So our next speaker is Rick Panin with his talk vapor phase, soldiering with
the deep fryer. So Rick has been doing hardware design design for some time now.
He actually considers himself a full stack developer from the hardware world. So
basically going from software to hardware, it's everything from doing circuits to
firmware development on embedded Linux. He usually does his stuff in small series
production in order to be able to give out some of the samples to the community where
he's also been spending a bunch of time. He's trying to slowly move the process of
being able to do as much as possible in- house. And this talk is a result of that
process. Please give a great round of applause, at least at home to Rick Panin.
Thank you.
Rick: Hi, welcome to my talk "Vapour phase soldering with a deep fryer". In this
talk, I first explain the reflow process in detail and then I'll show you how
vapour phase soldering works and how to do it with a cheap, deep fryer. Reflow
soldering basically consists of three steps. First, you apply some solder paste
to a circuit board. Then you place your components onto the solder paste, and
finally, you apply some heat to do the extra soldering. For that, you need some
solder paste, solder paste comes in 100 thousand varieties. Most of them have as
different melting points and different ingredients, but the common lead-free
paste that you use these days melt about 210 to 225 degrees Celsius. And the
majority of the solder paste has a limited shelf life and has to be kept in a fridge
if you're not using it. So for home use, I would recommend using the solder paste
that comes in syringes because it's a lesser amount and it probably won't go bad
unless you use a lot of solder paste. Also, it's a bit easier to apply it.
All Solder paste comes with temperature profile that tells you exactly how many
seconds you should ramp up the temperature to a certain amount and then you have a
soaking phase where for several seconds you keep the temperature at the same point
and then for a very short amount of time, you ramp up the temperature to the reflow
phase. That's when the actual soldiering happens and then you have to remove the
temperature to cool it down. For applying the solder paste, there are two basic
methods. The first one is a direct paste application, so you can do that manually
by just taking a syringe and applying a small amount of solder paste to each pad
where you want to put your SMD components. Then the next step would be a modified CMC
mill or a 3D printer where you put in a solder paste syringe as a tool head and
then load in your paste layer from your electronics design software and the
printer, then or the CMC mill automatically applies the solder paste to
the pads on the board. And for industrial applications, there are also inkjet
printer like devices that apply the solder paste automatically to PCBs. But these
devices are very expensive and probably not suitable for home use. For home users,
I would recommend getting a stencil for solder paste applications because stencil
have become very cheap and the recent years, and it's much simpler to apply the
solder paste with the stencil than doing it manually. So stencils can be used also
in different ways. The simple and cheapest one is just putting your boards on a desk
and using some tape to apply your stencil to it. So you position it over your board
and then you fix it to your desk. And after that, you use a rake to wipe your
solder paste to the board. I will show that later in the demo. For home users, I
would definitely recommend getting frameless stencils when you order a
stencil in your PCB house, you can always you always have a checkbox where you can
say, I want a frame or no frame. The first time I ordered a stencil, I took the frame
version and that looks like this. So you get a gigantic thing and there in the
middle, it's actually my ... can we see it. Maybe like this. There are. This is
the actual board and this is the stencil on it has some, some aluminum framing
around it, and that's definitely very expensive for shipping. So you'd rather
want something like this. So a frameless stencil that can be used very easily for
the method where you just put it on your desk. If you do a lot of the same boards,
then there are stencil printers, manual stencil printers. That's where you use the
stencils with a frame. But these stencil printers are not cheap, and I think the
the tape on desk method is pretty simple to use. So unless you make a batch
production of boards, I would always just get the frame, the stencil and do it on
your desk. For industrial environments, there are automatic stencil printers that
have a conveyor belt pull in the PCB, do all the positioning and then automatically
apply the solder paste to the stencil. After you have put the solder paste on
your board, then you need to place your components. Again, the cheapest way and
what what most home users will do is just take all the components manually with some
tweezers and put it on your board because of the way that reflow soldiering works.
And you will see that later in the demo. You don't have to position them too
exactly because the surface tension of the solder paste when it starts to melt will
pull the the components into position. So you don't have to be too precise with
positioning, you shouldn't place it right next to the footprint. But if if it's not
exactly where it should be, then this should be resolved while in the reflow
soldering process later. So I would always be recommending getting some good
tweezers. If you do the manual placement and not using the two euro things from the
DIY store because they will bend easily and so some good tweezers really help the
process. The next step would be a pick and place machine that takes a file from your
design program that has all the positions of the components and the rotation that it
needs after picking up the components from a reel or from a tray, and then use this
little suction cups to to place the components on the board. These have become
a little bit cheaper in the recent years, but it's quite a hassle to to program it
for a lot of components. So unless you're doing more than 20 boards or so, it's not
really worth getting a pick and place machine and programing it and getting all
of the rotation and and the pick up correctly. So, yeah, for projects where
you do one to five boards, always do the manual placement and then in industrial
environments, there are also these pick and place machine like in the mill. But
for very high volume production, there are also machines called chipshooters that
have a revolving turret that picks up components and then shoot them to the PCB.
Once your components are placed on the board, you will need to solder it. And the
cheapest method here is to use a hot air gun. If you ever did this, you will know
that it's not as easy as it looks. So you set your hot air gun to a temperature and
you set the airflow. And often, if you set the airflow too high, then you blow your
components off the board. Or if you set the temperature, you too high. You burn
some components or you de-solder stuff that you don't want to de-solder on other
parts of the board. So it's mostly used if you do replacement of single components.
So you want to rework a chip or replace one or if you do really just a few
components, then this can also be the method to use. But I'd always recommend if
you do that, then use some solder paste that has a lower melting point. So I
listed one from ChipQuick here that I am using for hot air reflowing and that melts
at just 135 degrees C, so that makes it way easier to get the setting right on
your hot air gun. The next thing is using a modified pizza oven, so you get a pizza
oven and you put some thermal couples into it to have a good temperature measurement.
And then most hobby users add some controller, for example, in arduino based
controller that then tries to keep the temperature profile that you've seen on
the solder paste. That works well for some stuff, but because some of these ovens
have these heating coils on the top, you have to be really careful with the
placement of your PCB underneath it because there are some spots that are
hotter and somewhat colder, and in general, it's it's hard to get good
results with a pizza oven. Often you have to add some some airflow to get a better
distribution of the temperature. Sometimes it's hard to ramp up the temperature fast
enough, and it's kind of a hassle. So I also use this method, and that's why I
switched to vapour phase soldering, because that's the process that is much
easier to control at home. In industrial environments, you have large reflow ovens
that have different zones with different temperature, and then you have a conveyor
belt and your PCB goes on this conveyor belt through the oven and through the
different zones and then by just adjusting the speed of the conveyor. It's very easy
to control the heat that is applied to the board. Instead of using an oven for reflow
soldering, you can also use vapor phase solder. And that's a very simple concept
that has been around since the 1970s. That works by using a phase chamber with a
heater on the bottom phase chambers just as sophisticated word for cooking pot. So,
yeah, just like a cooking pot, you have some kind of container and underneath it
you have a heat source and then inside of the container you have a liquid called
Galden. Galden is liquid plastic that has some very unique properties. So the most
important one is that it has a boiling temperature of about 200 degrees. So there
is Galden for different temperatures, just like solder paste. So there's one that
evaporates at 170 degrees, and some that evaporates up to 260 degrees. And now,
when you apply heat to this Galden, at some point it begins to boil and then it
forms a vapor that is heavier than air, so it stays at the bottom of this chamber.
And that way, you'll have a low temperature on the top of the chamber and
a higher temperature on the bottom of the chamber, and the temperature will be
exactly the boiling temperature of the Galden. So it's just like with water. If
you cook water, then you get water vapor. And unless you put it under pressure, the
water vapor will have exactly 100 degrees and not more. And that's just like with
the Galden vapor that if you have gotten that is has a boiling point of 230
degrees, then the vapor will have exactly 230 degrees. And unless all the Galden in
the phase chamber has evaporated, nothing will change. So you can never get it to a
high temperature. And in most of these chambers, for vapor phase soldering, you
also have a cooling system on the top. So because the Galden is pretty expensive,
you don't want to lose any of it. Now, if you put a PCB in this chamber and slowly
lower it into the vapor, then the temperature on the PCB will slowly rise to
the Galden boiling temperature. And as this Galden vapor condensates on the parts
of the PCB and it does it everywhere where the vapor attaches to the PCB, then it
will very evenly heat up all the components and also the solder paste on
the PCB to exactly the Galden's boiling temperature. And that way, you have a
process that's very easy to control because it's not really possible to
overheat your components, or the solder paste. So by timing the lowering and the
lifting of the PCB into the vapor, you can very nicely follow the temperature profile
of your soldering paste. One drawback of this process is that the Galden is very
expensive. So, if you have a large industrial vapor phase reflow oven, you
need some liters of it. And as you see, five liters costs about a thousand
dollars. But for the process I'm showing now with the small deep fryer, you just
need a very small amount. So I use about 250 ml, and at least in Europe, you can
get 400 milliliters of the 230 degree Galden at Beta Layout for €88. So for the
deep fryer vapour phase soldering, you need to buy a deep fryer for about 100
euros and Galden in for 90 euros, so the whole process can be done for under 200
euros. And if you're worried about the safety, Galden this actually very safe
because it's basically inert. So it's no problem if you breathe in the vapor or if
you even swallow it the. The Safety instructions that come with the Galden say
if you breathe it in, then you should go outside and take two or three deep
breaths. And if you swallow it, you should drink two glasses of water. In an
industrial environment, you have these large vapor phase machines that also use
the conveyor belt and automate the whole process. And these are very expensive, but
for lab use and prototyping. There are these smaller machines that also cost a
couple of thousand euros, but they are basically a container with a heater on the
bottom, a temperature probe and some kind of controller. And these are exactly the
same as deep fryers. So deep fryers also have some kind of heating coil at the
bottom, and they have the controller and somewhere there's a temperature probe to
keep the temperature that you set on the controller. And I've looked at lots of
these devices, and finally, I found one that fits very good to my use case and the
size of the boards that I'm usually making and that that is a WMF mini fryer. It is
quite small and it has a lid that is sealed, so there's not much vapor escaping
and a very nice thing, is that when the lid is closed by turning the handle, you
can lower and lift the basket inside. It has a container that can be taken out.
That is quite flat on the bottom. And that is also important because if you have the
heating coils inside of the container, you need a lot of the expensive Galden to put
that much in it, that it's that it fills it up to cover the heating rods. And
because of the heating rod here is in the bottom, that's you just need to about 250
millimeters. So the whole bottom is covered with Galden. The temperature
sensor in this device is just at the point where the if you put in cooking oil, then
it's just where the lower level indicator is on the container and the temperature
sensor is basically outside, and it measures the temperature of the container
at a certain height. When we're using this for a vapor phase soldering this
temperature sensor will be above the liquid, which is pretty nice because it
will basically measure the temperature of the vapor and not of the liquid. The only
drawback is that it can just be set to one hundred and ninety degrees and not more,
which is, I think, kind of due to the fact that you shouldn't try something like
potatoes with a higher temperature because there can be some cancerous stuff
developing if you fry it with too much heat. But that's no problem for vapor
phase soldiering. So we have to somehow modify it that we can turn the temperature
higher. Fortunately, this device doesn't have any electronics. It's all pretty
discreet. So it has the temperature probe and that has a certain resistance. And
then you have the knob in front where you set the temperature and you. That's also
just a potential meter where you set a resistance and then it just compares the
resistance of the temperature probe to the resistance that you set on this potential
meter. And if it's higher, it switches off the heater. So the you would just have to
turn the knob a little bit further than you can to have a higher temperature range
on that device, and you can do that by opening up the button. And then there's a
little metal piece that stops the potential meter from turning too far. You
can take a screwdriver and bend that up a bit, and I guess it works the same for all
of the cheap deep fryers on the market. And so they should be all basically the
same and just have a mechanical limiter that can be removed. So you you bend up
this metal piece and then you screw the bottom part back on. And then there's the
second limiter that you see when you take off the knob on the front. There's a
little plastic part that also stops the knob from turning to fall. So just take a
sharp knife and cut away that plastic part, and then you can turn the knob as
far as you want. To prevent too much of the precious Galden to escape through the
lid, we also need to add some cooling. I just used an old PC cooler that I found
somewhere in my basement. I also wanted to add water cooler at some point and looked
at some water coolers for graphics cards. But the ones I found were too expensive or
not really available or not really fitting. But I'm still looking to add
that, and then probably I would lose even less Galden through the lid. So now let me
show you how that all works. Here, I prepared the board and gluing it with some
double sided tape onto my desk and at some some old boards around it, the upper one I
also glued to the board. Then I put the stencil on it, taped it onto the other
board and used again and old board to rake the solder paste over it. And as you can
see, that works pretty nicely. So it's not that hard to use a total paste. No, I'm
putting some components to the bottom and I have attached temperature probe to the
basket. You don't really need that. It's just for this demo to show to show how it
works. The temperature probe is not working really well, so it's not 30
degrees where I'm doing this. It's plus minus 10 degrees. I think it was damaged
at some point. So you make sure that this enough Galden, that the whole bottom of
the container is covered with it. Then you put your basket with your board on it and
switch on the deep fryer. So I put it to about where 210 degrees would be if it
would be on the scale. And then it takes about three to four minutes until some
vapor is forming on the top of the PCB. Here I waited a bit too long because I had
to it figure how to handle the camera. So, you see, it's already starting to solder.
So I should have known it much sooner. But now, I'm lowering it. And as we can see,
the temperature is rising quickly to where it should be. And here you see through the
glass how the solder works and how the components are pulled into place by the
surface tension of the solder paste. And yeah, you can just watch it through this
window and see when everything is nice and shiny and everything is soldered. And then
you switch off the deep fryer, raise the basket again and wait for a few minutes
for it to cool down. I didn't wait long enough. So you see this some vapor
escaping. It's not dangerous, but it's expensive, so you should maybe wait a bit
longer. And now you see we have a nicely soldered board.
Herald: Thank you so much, Rick. I think it's really cool, like reducing the
friction in this entire process. I think it's important to keep make sure that it's
possible to like innovate with like low amounts of resources because as we've seen
before with the community, like, that's really something that drives things
forward. So questions and I was actually thinking about something myself like this
entire process. Like what has been one of the biggest obstacles? Because like
watching the talk, it seems like you've really overcome everything among the way
when there was a little itch or something like what has actually proved to have been
a problem because I guess there must have been something .
Rick: The biggest problem was finding the right deep fryer. So I, yeah, I ordered I
think about three different ones and now every now and then, I'm using my browser.
I get some advertisements for kitchen appliance and that would last for some
time. But yeah, finding one that can be modified easily. And that has this this
flat bottom. So yeah, I had ordered a lot of them and send them back. But finding
the right ones and then the process is pretty easy once you have the right one.
Also, the modification takes just a few minutes.
Herald: Sounds a lot like trial and error and that part. I mean, it's awesome that
it worked out and I guess I guess like it's just part of the process with like
the advertising stuff. Rick: So, yeah, if you if you do something
like that and want to misuse of pot and then use a private browser, chat for that
because I'm not really interested in kitchen appliances. But the algorithm
doesn't know that. Herald: That's that's great. Yeah, just
just. And now we will be taking the questions that have come in through the
internet. And so one person is asking, So if the Galden is 230 degrees, can it be?
Can the solder be lead-free? The solder paste, basically.
Rick: Yeah, yeah, I'm using lead-free solder, Yeah, it doesn't make sense to use
leaded solder with with this process because it works just fine. I know a lot
of people who who do who use the pizza oven method, all the cheap Chinese reflow
oven they use that as solder paste just because it's easier to get the lower
temperature right. But for this, it really doesn't matter. So it works great. This is
leaded solder paste. And also in the demo, I used to lead-free solder paste.
Herald: That's awesome, I think that was an important thing to to to be able to
have to figure out. So another person is asking So with the discussion about
fluorinated chemicals, is there a need to revisit the safety classification of the
Galden or like, is that fine? Rick: I think so. So you're really using
just a little of it and there is as long as you don't heat it up too much, it's
completely safe. If if you would manage to somehow heat up the gun above 290 degrees,
it would break down and there would be some hydrochloric acid coming out of it.
That would be very, very bad. But so so you have to make really sure that you have
enough Galden in it because the only way that that could happen, that you heat up
the vapor to too much, I think, would be to put too little in it. If it's just a
very little bit in it, it could be that the bottom gets too hot and then it could
break down. But you really it's hard to to get the vapor above 290 degrees if it's
not under pressure or anything. So I think it's pretty safe and it lasts very long.
So I probably I bought this 400 milliliters and it probably will last
forever. From time to time, there's some residue in the in the Galden, but you can
just run it through a coffee filter and then it's fine again. So it's you're not
really using it up. It's it's just like a tool and then it will last a very long
time. Herald: So I and extending and the last
thing, so someone who is a bit freaked out with chemicals and stuff like that, for
instance, me like, how do you actually go about it? Like, what's the absolute worst
thing that could happen? Rick: The worst thing is the hydrochloric
acid forming when when you get it too hot. So it's something so I would recommend to.
If you do that, do that outside. Take all the precautions use safety goggles, use,
use gloves and maybe also use your FFP2 mask if you're if you're really afraid of
it. And then if you if you do it outside and and never look away, if if Y-, they're
using it. So if you're done using it or if you walk away from it, disconnected from
the power. And yeah, as with everything. So so it's really hot when you don't want
something that's 230 degrees on your on your hands. So. So just don't be stupid.
Herald: Sounds like a sane precaution. Rick: But the government is actually. So
if you have seen the film The Abyss, it's it's an old science fiction movie where
they are underwater and they are breathing in a liquid. Was that his oxygen in it to
go deeper? And that is actually the same stuff. And there are. You can find
pictures on the internet where they have rats in and in small (glasses) with the
stuff in it, and they're breathing it. And so it's really, yeah, unless you make it
too hot, it's really inert and it doesn't react with anything.
Herald: I'll refrain from asking you how the movie ends.
Rick: I think there is a lot that I think I've seen it, but
Herald: No worries. The next question is do you need to do you need to remove the
condensed Galden vapour from the components or how does that work?
Rick: Um, there's actually very little on it. So they feel dry. So I don't I don't
clean the boards afterwards. I think I think that's fine and there's not really
much left. So, yeah, the stuff condensing on it. But I think most of it drops down
and they're not wet to the touch yourself. So, yeah, I don't I don't clean the boards
afterwards. Herald: OK. I think it's good in these
kinds of situations to like, figure out what someone who's a bit more experienced
or very more experienced like yourself basically handles and doesn't that kind of
situation. So one of the next questions is that if whether you have checked, if the
plastic can safely be heated to 250 degrees and I think they're basically
referring to the deep fryer here, Rick: oh, that's that's all on. There are
some plastic parts, but the container is this metal and there there is on the top
lid there are some plastic parts. I've made some experiments first and nothing
melted. But yeah, I have to see you see what happens. I've used it, I don't know,
10 or 20 times, and it's fine until now. But yeah, yeah, probably. This device is
not made for that kind of heat, but it's made for 190 degrees and up 230 is not too
far from that. So until now, it (keeps) up nicely. But again, it's a hack it's not
really, really made for this. For me, it works fine, but you have to be careful if
you try it out yourself. Herald: Cool. Thank you. I will just check
if there are any like last under falling or real questions, I don't know how you
say that in English. And I think that was actually everything for now. So as I said
previously Rick, like, thank you so much. It's it's really great, especially
considering that as the more you can take in at home, the easier and faster this
process will be and basically also lower the cost. And like I at least personally
feel that that's very important. So I want to say thank you. And I think that the
audience agrees with me. So thanks a lot. OK,
Rick: Then. Yeah, have fun soloing at home.
Herald: We will. Thanks. Bye Rick:bye
*RC3-postroll Music*
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