Soldering with no solder - Page 1
Forum section: electronics / general

author: lorth
author_rank: Contributor
timestamp: October 30, 2013, 03:21:07 pm
content: 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 thisSilver Epoxyand 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 thisConductive Silver Paste? Any recomendation?Thanks you very much!

author: nanofrog
author_rank: Super Contributor
timestamp: October 30, 2013, 03:59:15 pm
content: Check the datasheet. If there's nothing, contact the manufacturer of the sensor and see what they recommend.

author: Alana
author_rank: Frequent Contributor
timestamp: October 30, 2013, 04:07:32 pm
content: 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.

author: IanB
author_rank: Super Contributor
timestamp: October 30, 2013, 05:01:47 pm
content: Ask the manufacturer how they recommend the device to be mounted. They designed it, so they know how they expect people to use it.

author: lorth
author_rank: Contributor
timestamp: October 30, 2013, 05:12:00 pm
content: Quote from: IanB on October 30, 2013, 05:01:47 pmAlready did but, this is new to them also so no help there...

author: Monkeh
author_rank: Super Contributor
timestamp: October 30, 2013, 05:17:15 pm
content: Quote from: lorth on October 30, 2013, 05:12:00 pmSo they've designed and marketed a product.. and don't even know how to use it?

author: Stonent
author_rank: Super Contributor
timestamp: October 30, 2013, 05:59:21 pm
content: 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

author: lorth
author_rank: Contributor
timestamp: October 30, 2013, 06:21:57 pm
content: Quote from: Monkeh on October 30, 2013, 05:17:15 pmWe 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!

author: sca
author_rank: Regular Contributor
timestamp: October 30, 2013, 08:08:05 pm
content: ISTR some extremely small cameras being friction welded to flex PCBs...sca

author: tszaboo
author_rank: Super Contributor
timestamp: October 30, 2013, 08:13:44 pm
content: If it is DIP package, you can design the board for press-fit mounting maybe. Or socket it.

author: Fraser
author_rank: Super Contributor
timestamp: October 30, 2013, 10:36:11 pm
content: 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

author: tiago
author_rank: Contributor
timestamp: October 31, 2013, 01:49:59 am
content: Z-Axis tape depending on the pin to pin gap. Example below.https://www.sparkfun.com/products/12042

author: Stonent
author_rank: Super Contributor
timestamp: October 31, 2013, 08:14:04 am
content: Quote from: tiago on October 31, 2013, 01:49:59 amBeat ya to it!Quote from: Stonent on October 30, 2013, 05:59:21 pm

author: codeboy2k
author_rank: Super Contributor
timestamp: October 31, 2013, 09:43:39 am
content: Quote from: tiago on October 31, 2013, 01:49:59 amHah! It's Halloweeen...Sparkfun has a little ghost on the page... and try as you might, you can't catch it either

author: Stonent
author_rank: Super Contributor
timestamp: October 31, 2013, 10:43:39 am
content: Quote from: codeboy2k on October 31, 2013, 09:43:39 amWhat sorcery is this?!I was going to view the source to figure out how to catch the ghost and saw this:Code:___ _ ___/ __|_ __ __ _ _ _| |_| __| _ _ _\__ \ '_ \/ _` | '_| / / _| || | ' \|___/ .__/\__,_|_| |_\_\_| \_,_|_||_||_|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:___ _ ___/ __|_ __ __ _ _ _| |_| __| _ _ _\__ \ '_ \/ _` | '_| / / _| || | ' \|___/ .__/\__,_|_| |_\_\_| \_,_|_||_||_|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.

author: colotron
author_rank: Contributor
timestamp: October 31, 2013, 11:27:24 am
content: Quote from: Stonent on October 31, 2013, 08:14:04 amNice!!!, 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.

author: Stonent
author_rank: Super Contributor
timestamp: October 31, 2013, 12:16:06 pm
content: There's a video on spark fun on it. I don't think it's designed to be reused.

author: amyk
author_rank: Super Contributor
timestamp: October 31, 2013, 02:49:45 pm
content: Also more commonly known asanisotropic conductive film. Widely used for things like LCD connections and in mobile equipment.You can get a better deal on thatherefor ~$0.86/ft.

author: Fraser
author_rank: Super Contributor
timestamp: October 31, 2013, 03:51:28 pm
content: 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.

author: Stonent
author_rank: Super Contributor
timestamp: October 31, 2013, 07:44:28 pm
content: Quote from: StevenWhitney on October 31, 2013, 07:29:54 pmYeah I know, my apologies to any Welshmen who speak ROT13.

author: Marco
author_rank: Super Contributor
timestamp: October 31, 2013, 08:16:06 pm
content: Laser or ultrasonic wire bonding?

author: lorth
author_rank: Contributor
timestamp: October 31, 2013, 08:19:00 pm
content: Quote from: StevenWhitney on October 31, 2013, 01:47:49 amNDAs everywhere...Thank you everyone!

author: codeboy2k
author_rank: Super Contributor
timestamp: October 31, 2013, 09:17:56 pm
content: Quote from: Aurora on October 31, 2013, 03:51:28 pmYes, I am intrigued by it as well. I didn't know it existed until that post with the ghost...Quote from: colotron on October 31, 2013, 11:27:24 amThis 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 -> 0.4mmSome 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.

author: colotron
author_rank: Contributor
timestamp: November 01, 2013, 12:27:08 am
content: Quote from: codeboy2k on October 31, 2013, 09:17:56 pmGood 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.

author: mrflibble
author_rank: Super Contributor
timestamp: November 27, 2013, 05:00:53 am
content: I just noticed this stuff while readingbunniestudios, 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.