Vapour phase soldering with a deep fryer

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

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