Practical DIY or modest cost Vapor Phase - does it exist yet?

[gasmeter]

Hi

Well I have just ordered some custom heaters.
They are 2400W because in the UK we can use 13A or 16A feed , even 20A via the correct connector combination.

For 120V is either 1/2 the power and in fact if the heating system / insulation is designed well 1200W with no wasted energy is plenty.

My plan with the 2400W is just to speed things up and its over engineered.

My test systems using a Gastronorm used less than a Kw and it worked .
I didn't insulate anything and heat was being lost everywhere.. It just took a little longer.

Peter

[mrpackethead]

Hi

Well I have just ordered some custom heaters.
They are 2400W because in the UK we can use 13A or 16A feed , even 20A via the correct connector combination.

For 120V is either 1/2 the power and in fact if the heating system / insulation is designed well 1200W with no wasted energy is plenty.

My plan with the 2400W is just to speed things up and its over engineered.

My test systems using a Gastronorm used less than a Kw and it worked .
I didn't insulate anything and heat was being lost everywhere.. It just took a little longer.

Peter

Insulating it, could make your cool down really problematic,  You dont' want to be sitting at temp for too long.   I agree that having 1200W is probably enough

[gasmeter]

Hi

Cool-down is by water cooling .. So very fast.
Your right you can't use fan cooling when its insulated . Insulation though helps massively with the efficiency.

What I learned was that any system works be a tall pot or gastronorm, the issue comes in applying the heat efficiently and also efficient cool-down in order not to keep the board at elevated temperatures beyond the recommended profile time period.

Peter

[mrpackethead]

Hi

Cool-down is by water cooling .. So very fast.

You dont' want to cool down too fast either.  The cooling phase determines the grain structure of the solder joint. A fine grain structure provides the most reliable mechanical bond. To achieve this structure, a rapid cooling rate as the solder transitions from liquid (liquidus) to solid (solidus) is needed (the first ~50°C of cooling). HOWEVER The limiting factor for the maximum cooling rate is the stress that is exerted on the solder joint if the rate is too fast. This thermal stress, depending on the differences in CTE (coefficient of thermal expansion) of the joining surfaces, can fracture ortear the solder joint. The greater the difference in CTE of he joining materials and the cooling rate, the greater the thermal stress generated. A cooling rate of ~4°C/second is pretty typical.

Your right you can't use fan cooling when its insulated . Insulation though helps massively with the efficiency.

I'm really not to stressed about the efficiency of the system.   A very simple build is what i want to acehive.   Are you taking the container off the heater and then dunking in a water bath or similar?    My concern woudl be moving a board while the the solder is still molten, as it would be very easy to bump and then its all over!

[Smallsmt]

a rapid cooling rate as the solder transitions from liquid (liquidus) to solid (solidus) is needed

As I know, the first 20 degrees cooling should take place more slowly so that there is an ordered crystallization.
For this reason our reflow oven has a hold time in which the heating switches off but the fan for cooling does not start until a preset cooling temperature is reached.

[gasmeter]

Hi
My Mk1,2,3 sub release a - d (so many huge pots and gastronorm's left over from experiments ) anybody like a 100 Litre pot , or maybe a sweet little 60 Litre ?

On all my test builds I put the pcb on a static carrier and used forced air cooling on the outside of the tank / heater.
This did work but its very easy to spend too much time at a elevated temperature .

My latest build is meant to be for small business's like my own to use so it has pcb handling and it can lower and raise the pcb, so the pcb handling is more complicated and automated with safety interlocks etc.

The best system I saw for a home machine for raising and lowering is this excellent video / idea

https://youtu.be/8JRXbwYZmrU

Plus you get to practice your south African accent.

Amazingly only 5 likes on his genius video

Replace his can with a Gastronorm and Bob's your Uncle , Nellies your aunt !

Peter

[mrpackethead]

This did work but its very easy to spend too much time at a elevated temperature .

Once i removed the cowling off the bottom of the frying pan to expose it to more air flow, and put a decent fan on, i'm getting cooling of 6degC/sec which is fast enough..    I did try some experirments with water, which worked, but massively increased the complexity of the build.     

My latest build is meant to be for small business's like my own to use so it has pcb handling and it can lower and raise the pcb, so the pcb handling is more complicated and automated with safety interlocks etc.

my project really was about answering this question..  and i think i've found out that now a Practical and low cost DIY solution is avaialble.   However in the mean time, i'm pretty confident that im going to be able to scale it sideways so that i have three pans side by side, so i can use it for my low volume production.   

The best system I saw for a home machine for raising and lowering is this excellent video / idea

https://youtu.be/8JRXbwYZmrU

This video does demonstrate how simple it is to get resonable results.  He does mention that you can bump the board while its cooling and as your panels get bigger ( mine are A4 page size ) that is more and more of a issue.   And at the end of the video you see lots of tombstones.
I've been finding that its quite possible to get very good curves with a bit more effort with the controls, and that really sorts out tombstoning, Generally this is becuase you've got thermal inbalance between the ends..  ( one end goes liquid first ).     

[gasmeter]

a rapid cooling rate as the solder transitions from liquid (liquidus) to solid (solidus) is needed

As I know, the first 20 degrees cooling should take place more slowly so that there is an ordered crystallization.
For this reason our reflow oven has a hold time in which the heating switches off but the fan for cooling does not start until a preset cooling temperature is reached.

Thanks for this sage advice.
When my next system is built it will have a cooled inner lid section running continuously and a more severe directly coupled water cooler to the heating assembly for the Galden.
My plan untried as yet is

at the end of the cycle

1/ Shut off the Galden heater
2/ Raise the board at a controlled rate into the cooler region above the Galden and below the cooled plate suspended from the lid.
3/ Use water cooling to reduce the Galden temperature to the point where the lid can be opened and the board removed .

My plan is to reduce the Galden to say something around 100deg C rather than cooling it right down between cycles to speed up cycle time over multiple panels. Safety aspects of this have been thought through.

Peter

[mrpackethead]

For this reason our reflow oven has a hold time in which the heating switches off but the fan for cooling does not start until a preset cooling temperature is reached.

Thanks for this sage advice.

I have never seen anything that suggests that a 'slower' rate at the start of cooling is appropriate. In fact the opposite. The faster you can cool the better, and this is the first time i've ever heard this.    None of the datasheets for the solder i've seen suggest this.   I'd go and check this out before i made any more design decisions about it.     THe limiting factor for your solder cool down rate is the mechanical stress's, and most pastes will suggest cooling rates of between 4 and 10 C/sec

[KaneTW]

Cool down should be done quickly, but not too fast. I see ramp rates of rec. -4C/s to not faster than -10C/s

The cool down rate of the profile should be controlled within 4°C per second. In general, a faster cool down rate will result in a finer grain structure and a stronger and shinier solder joint. However, exceeding 4°C per second could result in thermal shock to the assembly.

https://aimsolder.com/technical-articles/reflow-profiling-time-above-liquidus

Would have to do some paper search later on for something more detailed.

[Kjelt]

Usually the max. ramp down speeds is aprox. twice the max. ramp up speed.
Example from WE says:
-  max ramp up     speed is 3^oC
-  max ramp down speed is 6^oC

[Smallsmt]

For this reason our reflow oven has a hold time in which the heating switches off but the fan for cooling does not start until a preset cooling temperature is reached.

Thanks for this sage advice.

I have never seen anything that suggests that a 'slower' rate at the start of cooling is appropriate. In fact the opposite. The faster you can cool the better, and this is the first time i've ever heard this.    None of the datasheets for the solder i've seen suggest this.   I'd go and check this out before i made any more design decisions about it.     THe limiting factor for your solder cool down rate is the mechanical stress's, and most pastes will suggest cooling rates of between 4 and 10 C/sec

It influences the crystallization of the tin, the solder joints look better and have a flat surface.
When the tin is solid, the cooling ramp starts, which triggers heating phases in our reflow oven if it cools too quickly.

[Smallsmt]

How about a galden chamber that can get closed when elevator moved the PCB up to speed up processing?

[KaneTW]

For this reason our reflow oven has a hold time in which the heating switches off but the fan for cooling does not start until a preset cooling temperature is reached.

Thanks for this sage advice.

I have never seen anything that suggests that a 'slower' rate at the start of cooling is appropriate. In fact the opposite. The faster you can cool the better, and this is the first time i've ever heard this.    None of the datasheets for the solder i've seen suggest this.   I'd go and check this out before i made any more design decisions about it.     THe limiting factor for your solder cool down rate is the mechanical stress's, and most pastes will suggest cooling rates of between 4 and 10 C/sec

It influences the crystallization of the tin, the solder joints look better and have a flat surface.
When the tin is solid, the cooling ramp starts, which triggers heating phases in our reflow oven if it cools too quickly.

I've never seen this recommended in a profile. While this sounds plausible, I'd like some references stating that the resulting structure is better.

[Smallsmt]

You can check the examples on our oven page https://www.smallsmt.biz/reflow-oven-hr-300/

I can do some photos using inspection system in the next days.

All of the photos show used this kind of cooling scheme. The pastes was GC10 a lead free paste.

[mairo]

You can check the examples on our oven page https://www.smallsmt.biz/reflow-oven-hr-300/

I think you need to add the max temperature that the oven can achieve on the main specs shown on the provided link. How is the cooling done? Is this your design / manufacturing, or is a re-branded Chinese oven?

[mairo]

Reading the metal plate at the back of the oven 'wenzhou small technologies" I guess, answers my question in regards to the manufacturer.

[Smallsmt]

I think you need to add the max temperature that the oven can achieve on the main specs shown on the provided link.
How is the cooling done? Is this your design / manufacturing, or is a re-branded Chinese oven?

MAX Temperature is 300C°. For constant temperature mode you should keep below 220C° max.
Cooling is done by exhaust vent and temperature rate controlled using heater.
Yes the oven is a modified re-branded oven.

Whenzhou Small Technologies is our chinese registered name for SMALLSMT in china you can't use a simple brand name for registration for chinese government.

[mrpackethead]

the project is moving ahead ( albeit slowly as its an 'extra' afterhours thing ). .

I have posted some python code and the json that describes the reflow curve.   While we are doing this specifically for VP, the controller coudl infact be used for lots of things.    I'll add the pid to the code, and improve the timing loop very shortly.

https://www.eevblog.com/forum/projects/diy-vapour-phase-frying-pan-project/25/

[gasmeter]

Hi All

I'm ordering some Galden LS230 for myself from europe (5Kg ) for myself in 2-3 weeks.
If enough people want smaller amounts I am happy to pad up my order and combine postage etc.

I don't know the landed price in the Uk as yet but it's better than the prices I was quoted from anywhere else.

If enough people are interested then I can work out a firm-ish price (subject to euro rate etc).

Let me know if interested in Kg you would like, then I will buy bottles and decant / weigh from the 5l container.

I just want to see if there  is any interest at the moment.


Peter

[mrpackethead]

For the frying pan, you only need about 80ml.    Thats about 130g.      250ml would last most hobby level folks for a long time, if you are careful with it.

[kony]

Virgin from manufacturer, or used and recycled?
Preliminarily I am interested in 1kg of fresh - but that depends on exact asking price.

[mrpackethead]

Virgin from manufacturer, or used and recycled?
Preliminarily I am interested in 1kg of fresh - but that depends on exact asking price.

I'd probalby not buy recycled, just becuase i dont' know whats been in it..  However, it does clean up very well.   I've cycled mine 100's of time.  I perodically run it through a coffee filter folded in quaters, through a funnel.    You get flux and other mis bits of crap in it, and the paper seems to clean it up pretty well..

[kony]

The process of recycling is not a problem - that you don't get assay of what the recycled material is in what boiling point fractions is. Hence why am I interested only in fresh one from manufacturer.

[mrpackethead]

It certainly is a mix.   The difference between the HS and LS grades is simply how tightly it was distilled.    I have not tryed to use the HS grade, but its quite a bit cheaper and it might actually be just fine.