Soldering with no solder

[lorth]

Hi all!!!!

I'm designing a PCB that will be used to test some novel sensor. This sensor comes in a chip that is made of a material that can not be soldered using tin (solder) but it is conductive. We have tested with this Silver Epoxy and it works. However, I was wondering if there is something better? with better electrical characteristics?

Also, for some of the experiments, we don't want to "solder" the xip on the PCB, so i wanted to put some sort of conductive paste to increase conductivity. What do you think about this Conductive Silver Paste? Any recomendation?


Thanks you very much!

[nanofrog]

Check the datasheet. If there's nothing, contact the manufacturer of the sensor and see what they recommend.

[Alana]

If soldering iron temperature is an issue try to get solder that contains indium. I remember it was used for laser diodes in dvdrom/rw due to problems with typical solder overheating component.

[IanB]

Ask the manufacturer how they recommend the device to be mounted. They designed it, so they know how they expect people to use it.

[lorth]

Ask the manufacturer how they recommend the device to be mounted. They designed it, so they know how they expect people to use it.

Already did but, this is new to them also so no help there...

[Monkeh]

Ask the manufacturer how they recommend the device to be mounted. They designed it, so they know how they expect people to use it.

Already did but, this is new to them also so no help there...

So they've designed and marketed a product.. and don't even know how to use it?

[Stonent]

Z axis tape by 3M. Conductive on the Z axis only. I saw a QFP Atmega stuck to an Arduino using nothing but this and no solder and it worked

[lorth]

Ask the manufacturer how they recommend the device to be mounted. They designed it, so they know how they expect people to use it.

Already did but, this is new to them also so no help there...

So they've designed and marketed a product.. and don't even know how to use it?

We are designing it together, it is a research product that it's the first of it's kind and we are using it in a non-standard way... So quite lots of unknowns. Basically, this board will be used to characterize the device...

Thanks Stonent, I'll check it out!

[sca]

ISTR some extremely small cameras being friction welded to flex PCBs...

sca

[tszaboo]

If it is DIP package, you can design the board for press-fit mounting maybe. Or socket it.

[Fraser]

I would go for a suitable housing for the sensor that fixes to the PCB in a standard manner...tabs, clips, solder, rivets or screws. I would use gold plated sprung contacts on the PCB to connect to the sensor pins or pads that are exposed within the housing underside. This would be a mechanically sound solution compared to reliance on conductivity in epoxies or the strength of adhesive in conductive tapes. I am 'old school' and believe good mechanical contact to be superior to conductive glues and such 

[tiago]

Z-Axis tape depending on the pin to pin gap. Example below.

https://www.sparkfun.com/products/12042

[Stonent]

Z-Axis tape depending on the pin to pin gap. Example below.

https://www.sparkfun.com/products/12042

Beat ya to it!

Z axis tape by 3M. Conductive on the Z axis only. I saw a QFP Atmega stuck to an Arduino using nothing but this and no solder and it worked

[codeboy2k]

Z-Axis tape depending on the pin to pin gap. Example below.

https://www.sparkfun.com/products/12042

Hah! It's Halloweeen...Sparkfun has a little ghost on the page... and try as you might, you can't catch it either

[Stonent]

Z-Axis tape depending on the pin to pin gap. Example below.

https://www.sparkfun.com/products/12042

Hah! It's Halloweeen...Sparkfun has a little ghost on the page... and try as you might, you can't catch it either

What sorcery is this?!

I was going to view the source to figure out how to catch the ghost and saw this:

Code: [Select]

    ___                _   ___
       / __|_ __  __ _ _ _| |_| __|  _ _ _
       \__ \ '_ \/ _` | '_| / / _| || | ' \
       |___/ .__/\__,_|_| |_\_\_| \_,_|_||_|
           |_|

      Url gurer, pbqr crrcre! Lbh zhfg or n erny areq!

      Gb fubj bhe fhccbeg, hfr pbqr VFNJLBHEFBHEPR ng purpxbhg sbe 10% bss lbhe arkg beqre.
      Qba'g gryy nalbar, jr jnag gb fnir guvf fcrpvny pbqr sbe fcrpvny crbcyr jub ivrj fbhepr :)

      Unir n avpr ivfvg!
What is that Gaelic? Welsh?

Code: [Select]

    ___                _   ___
       / __|_ __  __ _ _ _| |_| __|  _ _ _
       \__ \ '_ \/ _` | '_| / / _| || | ' \
       |___/ .__/\__,_|_| |_\_\_| \_,_|_||_|
           |_|

      Hey there, code peeper! You must be a real nerd!

      To show our support, use code (REMOVED BY STONENT) at checkout for 10% off your next order.
      Don't tell anyone, we want to save this special code for special people who view source :)
I guess you'll have to figure it out to get the code.

[colotron]

Z-Axis tape depending on the pin to pin gap. Example below.

https://www.sparkfun.com/products/12042

Beat ya to it!

Z axis tape by 3M. Conductive on the Z axis only. I saw a QFP Atmega stuck to an Arduino using nothing but this and no solder and it worked

Nice!!!, could be used to prototype qfn parts? (pcb with appropriate footprint + tape + component). Does the tape comes off easily? -> to reuse footprint with different components.

[Stonent]

There's a video on spark fun on it. I don't think it's designed to be reused.

[amyk]

Also more commonly known as anisotropic conductive film. Widely used for things like LCD connections and in mobile equipment.

You can get a better deal on that here for ~$0.86/ft.

[Fraser]

That 3M tape is certainly very interesting 'stuff'. I will have to buy some for FPC repair work.

The down side of this connection technique is its fragility. 3M advise clamping to maintain reliable contact (not a surprise when you consider the physics of the interconnection technique). It is also quite sensitive to temperature , even when applied. This would make it unsuitable for ant sensor that need to be reliable over a large range of temperatures, especially over 70 degrees Celcius.

In my experience, sensors tend to be doing something important as part of a process, unreliability of connectivity to such a sensor is not usually an option as it can cause production of corrupt data or even system failure. We do not know the nature of the sensor that is being discussed here but this 'magic' product needs to be used with care and consideration of potential reliability issues. This applies during prototyping and final manufacturing.

[Stonent]

Z-Axis tape depending on the pin to pin gap. Example below.

https://www.sparkfun.com/products/12042

Hah! It's Halloweeen...Sparkfun has a little ghost on the page... and try as you might, you can't catch it either

What sorcery is this?!

I was going to view the source to figure out how to catch the ghost and saw this:

Code: [Select]

    ___                _   ___
       / __|_ __  __ _ _ _| |_| __|  _ _ _
       \__ \ '_ \/ _` | '_| / / _| || | ' \
       |___/ .__/\__,_|_| |_\_\_| \_,_|_||_|
           |_|

      Url gurer, pbqr crrcre! Lbh zhfg or n erny areq!

      Gb fubj bhe fhccbeg, hfr pbqr VFNJLBHEFBHEPR ng purpxbhg sbe 10% bss lbhe arkg beqre.
      Qba'g gryy nalbar, jr jnag gb fnir guvf fcrpvny pbqr sbe fcrpvny crbcyr jub ivrj fbhepr :)

      Unir n avpr ivfvg!
What is that Gaelic? Welsh?

Code: [Select]

    ___                _   ___
       / __|_ __  __ _ _ _| |_| __|  _ _ _
       \__ \ '_ \/ _` | '_| / / _| || | ' \
       |___/ .__/\__,_|_| |_\_\_| \_,_|_||_|
           |_|

      Hey there, code peeper! You must be a real nerd!

      To show our support, use code (REMOVED BY STONENT) at checkout for 10% off your next order.
      Don't tell anyone, we want to save this special code for special people who view source :)
I guess you'll have to figure it out to get the code.

It's just ROT13...

Yeah I know, my apologies to any Welshmen who speak ROT13.

[Marco]

Laser or ultrasonic wire bonding?

[lorth]

What exactly is this sensor? 

You could always use a socket.

NDAs everywhere... 

Thank you everyone!

[codeboy2k]

That 3M tape is certainly very interesting 'stuff'. I will have to buy some for FPC repair work.

Yes, I am intrigued by it as well. I didn't know it existed until that post with the ghost...

Nice!!!, could be used to prototype qfn parts? (pcb with appropriate footprint + tape + component). Does the tape comes off easily? -> to reuse footprint with different components.

This tape might make it easier to prototype some BGA and DFN packages, as long as the space between pads is larger than the minimum gap listed on the tape datasheet -> 0.4mm

Some 3mm x 3mm or 4mm x 4mm DFN's are 0.50mm pad to pad with a 0.25mm pad width. This leaves 0.25mm gap between the pads, which is too small for this tape. But larger DFNs and BGA will work if they meet the needed specs.

I'll have to spend more time to search around, maybe they make another adhesive tape or a paste that has finer particles and better specs down to 0.25mm or so. 

[colotron]

...
Some 3mm x 3mm or 4mm x 4mm DFN's are 0.50mm pad to pad with a 0.25mm pad width. This leaves 0.25mm gap between the pads, which is too small for this tape. But larger DFNs and BGA will work if they meet the needed specs.
...

Good point, and as mentioned before, adding low reliability and the need to press the component to the tape makes it a poor choice for qfn prototyping. Discarded.

[mrflibble]

I just noticed this stuff while reading bunniestudios, and sure enough there's an EEVblog thread about it.

This 3M tape looks pretty interesting for prototyping and whatnot. Has anyone had a chance to try it out? Any findings?

Pricing currently is pretty steep though.  But oh well, that'll come down in the future.