DIY hotbar bonding machine

[Bondguy]

Has anyone tried to make a DIY device that works like a hotbar bonding machine?
I need only from time to time to change FPC( flexible printed circuits) on LCD ,using ACF( anisotropic conductive film),
so spending about several thousand USD on that machine is not good for me.
Your ideas would be appreciated

[Precipice]

Can you not just run a dry soldering iron tip over it, and hope? Possibly using an extra layer of kapton to protect things, spread the pressure a bit and avoid overtemp? I've done that in the past, but the results have never been as sturdy as I'd like. OK if there's no further flexing, though.
If you need the reassurance of doing it by the book, then I don'y think you'll be able to avoid building something substantially similar to a proper hot bar machine, with a massive PSU and carefully crafted thermodes.
Looking at mine, I don't think I could build it for <£2000 - it's very sturdy, and I really like building things...

[Bondguy]

@Precipice:
What kind of the machine do you use?
For me it is OK, to spend about 1500 USD on that machine

[Precipice]

Last discussion was here, including a description of my machine...
https://www.eevblog.com/forum/chat/what-technology-to-use/msg493520/#msg493520   
If you're not in a hurry, your budget should eventually get you a second hand machine.

[Bondguy]

So, I checked
http://www.labx.com/v2/spiderdealer2/vistasearchdetails.cfm?lvid=29897426#MoreDesc
the machine looks OK, but not sure I fully understand the description that says

Unitek Miyachi 1-219-02-03 Uniflow UNFA4/240 4 KW, pulsed thermode solder reflow system, 4" wide thermode capacity, 180A/EZ air operated head. PIX2 PIX3 240 volt input
Does it mean the power supply can supply  4000W/240V =16,6A ?

4" wide thermode capacity
What does it mean? Thickness of thermode?

180A/EZ air operated head.
What does it mean?

PIX2 PIX3 240 volt input
What does PIX2 PIX3 mean?

Thank you for answers

[nanofrog]

If you're dead set on a DIY version, perhaps make a hot bar out of a modified soldering station (= heating element set inside a metal bar & thermocouple/PTC, ... set on the outside of the bar), and the bar is mounted to a small arbor press.   

[Precipice]

Problem is, you're trying to let the adhesive cool while you're still applying pressure. That's what all the messing about with low thermal masses and fast heat/cool times is about.
Obviously, how much you really need this, is open to experimentation, but it's what keeps things interesting.
As I said, I eventually scored a cheap machine off ebay, and stopped worrying!

[Precipice]

Does it mean the power supply can supply  4000W/240V =16,6A ?

No, it takes 16.6A from the wall, at 240V. It drops that down to a thousand amps or so at 4V (and lower voltages / currents).

4" wide thermode capacity
What does it mean? Thickness of thermode?

That's the width of the connector you're heating. Thermodes are available in a lot of widths. You normally want th width to be only a little wider than the connector, as there's usually stuff next to the connection that you don't want to compress or heat.
The thermodes are also as thin as possible - for instance, a 17F1000 is 1.000" wide, and .075" thick.
However, they can't be too thin, since there's a lot of mechanical force, and current, and heat going on.

180A/EZ air operated head.
What does it mean?

That just means it uses a compressed air cylinder to press the thermode against the connector. Once the pressure is right, the machine applies a current, controlled to meet the required temperature profile.
A typical soldering profile would be
Time  Temp
0s      Ambient
1s      150oC preheat
3s      300oC reflow
5s      180oC cooling

A typical Z-tape profile would be cooler, and very tape and substrate specific.

PIX2 PIX3 240 volt input
What does PIX2 PIX3 mean?

Not a clue!

A search for
Uniflow 2 Technical Manual.pdf
and
thermode selection guide

should give you some useful stuff.

[robrenz]

If you're dead set on a DIY version, perhaps make a hot bar out of a modified soldering station (= heating element set inside a metal bar & thermocouple/PTC, ... set on the outside of the bar), and the bar is mounted to a small arbor press.   

Just use an appropriate JBC wide tip. Set the sleep temp to 90degF and the on temp to whatever you need. Use a second handpiece in the holster to control the on/sleep cycle. make a fixture to hold the tip and apply pressure. Tough to beat the thermal response without using a thermode.

[Precipice]

Certainly worth a go - I was trying similar with a wide Metcal bit.
Bear in mind that, without some liquid solder to fill in gaps, the bit needs to be very flat and straight - more than you'd expect was necessary for straight soldering. You might need to fettle it a bit - but even if the cladding gets damaged, it's no real problem, as there's no solder to dissolve things.
Getting the temperature to ramp up and down quickly enough to avoid doing damage will be the challenge - but challenges are fun. Thermocouples bonded to the tip will help.
Trying lots of times will also help - but could chew through panels and boards at a fearsome rate. You don't get many tries before things get unusable.

One thing I wondered about, but never tried, was to drag a smaller bit across the joint, with some kind of a plastic pressure plate following the tip. That would get the high pressure and high temperature ramp rates, both up and down - although not over the whole connector at once. If I was trying this again, I'd probably resurrect this scheme, to see if it was a goer.

[nanofrog]

Problem is, you're trying to let the adhesive cool while you're still applying pressure. That's what all the messing about with low thermal masses and fast heat/cool times is about.
Obviously, how much you really need this, is open to experimentation, but it's what keeps things interesting.
As I said, I eventually scored a cheap machine off ebay, and stopped worrying!

Just use a station that allows for a profile (or design everything electronic from the ground up yourself if so inclined; mechanical too if it happens to be robrenz for example  ). Almost certainly need some experimentation to get the profile right for whatever's been cobbled together, but that's part of the fun. 

Good that you found a machine at such an excellent price BTW.  Used is certainly easier, but it would depend on price for most.  Hopefully possible within the OP's budget.

[Bondguy]

Thanks for the feedbacks.
I was also thinking about using a  PID controller that allows setting temperature profiles. It can be used with  SSR( solid state relay) 40A, so I think it can be enough.Or not?? A mechanical part should not be a big problem. I can have it made by a  local company at a fraction of the price.

@precipice:Bear in mind that, without some liquid solder to fill in gaps, the bit needs to be very flat and straight -do you mean your machine uses some liquid solder to fill in gaps?

I also found out this machiche. Price is about 800 USD. What do you think about this machine( advantages/disadvantages)?
http://www.leko.com.cn/ligaomei_en/tools_info.asp?keyno=171

[Precipice]

@precipice:Bear in mind that, without some liquid solder to fill in gaps, the bit needs to be very flat and straight -do you mean your machine uses some liquid solder to fill in gaps?

No - it's that soldering iron tips don't have to be super-flat, s solder will fill in any gaps. When you're pressing a dry bit into a plastic cover, it needs to be properly flat, or you'll get wildly varying pressures.

I also found out this machiche. Price is about 800 USD. What do you think about this machine( advantages/disadvantages)?
http://www.leko.com.cn/ligaomei_en/tools_info.asp?keyno=171

It's not a pulse machine, it's just a constant heat bar, with pressure.
Read the data on your chosen Z-tape and connectors, to see if that's going to work. It might.
That manufacturer also lists pulse machines, but I suspect they cost more.

[Bondguy]

Thanks for the reply.
I was recommended to use Hitachi type AC7206 and MF331.
When you check the enclosed docs , do you think it is necessary to use a pulse heating machine or just a constant heating machine?
(I could not find there any temperature profiles but there maybe  more detailed docs somewhere  )
And what kind of Z-tape do you consider the best?

[Precipice]

Unfortunately, this is now well outside my experience. Because I've got my real machine, I just do what the data calls for, and things seem to bond OK. The machine is back in storage, so I can't even have an experiment for you, I'm afraid.
I  can't see any mention in those tape datasheets as to whether pressure needs to be applied as the adhesive cools, just times and temperatures. Note that the glue temperature is almost completely unrelated to the thermode (or hot bar) temperature, so you're going to have to experiment anyway. Can you get a machine on trial, and test it?
Are you making prototypes or product?