TAB ACF bonding - Page 1
Forum section: electronics / projects

author: AhmedAbuShamla
author_rank: Contributor
timestamp: January 07, 2016, 01:20:25 am
content: helloi know this is my first topic in here but bare with mei have made (almost) a TAB ACF machinei'm done with the head and the power supply still remains the mechanics and the thermocouple to interface to control boardi just need to know if is it possible in any way to use the same TAB and rebond it after cleaning from the LCD panel side ?any thoughts would be helpful guys

author: CaveMannDave
author_rank: Regular Contributor
timestamp: January 07, 2016, 06:05:08 am
content: Greetings:Is this a riddle?What is TAB ACF?If you could be a bit clearer, more people (so far -0-) might chime in to assist you.I may be out of the loop of current technology, but that sounds to me like some process for mass termination, similar to hot-bar bonding; that, or perhaps elastomer zebra-strip connections: but without knowing what you want, how can we provide it?Clarify.Cheers,DaveAnd, it's BEAR, as in carry, not bare, as in uncovered.

author: AhmedAbuShamla
author_rank: Contributor
timestamp: January 07, 2016, 10:15:28 pm
content: tab contains the driver ic (Chip On Flex) which in turn connects between lcd panel and the driver board

author: CaveMannDave
author_rank: Regular Contributor
timestamp: January 08, 2016, 04:08:27 am
content: Greetings:You still only offer an low-detailled photo (looks like a string of condoms), with a web address that tells nothing useful; If you seek advice, you may want to give out links that lead to specific details of what you are attempting, instead of expecting others to do research/read your mind... Just a suggestion...Now, reading between the (remarkably blurry) lines, I can only assume this has something to do with a translation chip on a flex/film interconnect strip, and that you want to reuse it AFTER it has once been bonded, by some advanced SYSTEM of conductive "whatever", by "cleaning" it, of WHAT you never mention, and then re-bonding, by unknown methods, to save (how much?) per assembly?An I close?Generally, almost ANY conductive adhesive/ink/metallization/whatever CAN be contacted by SOME means, but if may be incompatible/expensive/labour-intensive to do so, with the current process.You implied a home-brew type machine, but gave no clue as to the "productivity" you need or expect: is all this to save a handful of of under $30.00 US "TABS", or are you looking at 1000+ assemblies using "TABS" of refined Unobtanium?What are you REALLY trying to accomplish, here?I REALLY would like to know!Cheers,Dave

author: AhmedAbuShamla
author_rank: Contributor
timestamp: January 09, 2016, 12:30:03 am
content: yes that does look really like a condom roll XDwell since u wanna know the whole storyanyone who works in lcd repairing should know these TABs but i'll explain anywaywhere i live i can't order the machine nor those TABs its very difficult to do soits not about money or saving a few bucks its about availabilityits not available here to fix lcd panels with faulty TAB driversmy end goal is being able to service these faulty LCD panels and try to fix the problems associated with themyes my previous replies were dodgy (at best) but i'll try and explain more and morei'll post a picture and a video on youtube showing the actual process and machineanyway i have lots and lots of used LCD panels which have perfectly good TAB drivers so i want to be able to replace faulty ones with thoseimagine like fixing a faulty circuit but instead of soldering components i want to rebond those flex cable or bond them anew altogetherfor now i expect and i'll be trying it next week to bond the portion of the TAB going to the driver boardi really hope i've made my case hereto sum i'm making the ACF bonding machinebut i wanna know if i can reuse old (already bonded) TABsand if anyone has done it before ? or its impossible ? or is it bothersome ?

author: CaveMannDave
author_rank: Regular Contributor
timestamp: January 09, 2016, 03:18:29 am
content: Greetings:Thank you for clearing most of that up.I now recognise what they are and what they do. I have seen them frequently.Whether these TABs can be re-used seems to primarily depend on the integrity of the traces on the flex substrate AND the LCD glass, after the removal and "cleaning" has been done; if trace conduction is poor, you may need to repair it (them) with some kind of conductive ink, and hope it survives the further handling and bonding steps.An "INK" I seem to recall seeing, recently, used for "printing" circuits on many substrates, was a two-stage system of two relatively available reagents, one a compound of silver ions, the other that converted the first to silver metal.ISTR, they used it in an ink-jet printer, different tanks, and could print usable circuitry on even paper or cloth, using many passes. Fill two Rapidograph pens, wait between stages, retrace, and you may have something usable. YMMVI also saw something about alloying Gallium metal and something else (metal?), and drawing traces on many substrates, but I don't know how it was "fixed" to prevent smearing.AFTER you have reliable traces, the next challenge is bonding, without shorts or opens, that will survive handling. If you can get a supplier to provide a Thermosetting/UVcured conductive adhesive, or find a sufficiently low-temperature alloy paste to bond the LCD traces to the flex traces (bearing in mind the almost-certain differences in Thermal-coefficient-of-expansion between glass and plastic substrate, which can generate ENORMOUS shear forces) you may be getting toward your goal.NEXT, is, how do you plan to APPLY the adherent agent in a fine pattern, thin enough to not "mush" over and create shorts, but enough to make reliable connections/bonds? Silk screen/stencil is good, if Volume justifies, but hand application is cheaper for low-volume.You said nothing about the initial condition (pre- and post- "cleaning", as to whether is enough residual, re-usable bonding/conductive material to reasonably expect a second try to work: I have assumed in the above that there is not; correct me if I err.I don't want to try to kill your "buzz" of finding a refurbishment process of your own, and make it profitable, but I want to make you aware that Engineering, especially Manufacturing, is full of "Traps for Young Players", and the road can be very treacherous if you don't make the right turnings.Engineering is Hard.I hope I have helped: Or I can try again, if I missed something.Cheers,DaveP.S.I just watched the video, and one after that, about Anisotropic-conductive-films, so if your LCD/flex circuit have clean and good traces, I can see no hindrance to re-use, assuming clean surfaces.Do you have a supplier of this Epoxide tape? If so, you may have a winner!Sorry I jumped before I looked.I would just advise absolute flatness of contact (within the compressibility of the virgin tape, and watch repeatability of temps and clamping force to prevent cracking of glass.D.

author: AhmedAbuShamla
author_rank: Contributor
timestamp: January 09, 2016, 06:41:13 am
content: u're right manu're absolutely right about the condition of the lcd substrait ink being in good condition after cleaning and the TAB tracks being cleaned , its what my logical mind and thinking was processing and concluded it would work if all critereas metas for the conductive tape i think i can get some in a month or soi'm intrigued about the ink tracing on the LCD panel itself if it can be repaired , idk whats the parameters nor the type of material used is it standardized or every manufacture have their own "secret sauce "about adherent agent ..its a tape like a double-sided tape but with nano particles of either Au Ag or even compounds of conductive material sometimes even gold nano particlesi know getting the force and the temp just right not to destroy the lcd panel or the flexits gonna take time i know but with determination and enough time i think i can pull this offthe tape has datasheet which says how much force and temp and even a graph of (Time vs Temp) and pre-bond procedure and final bond proceduremost of them say the pressure is around 1-3 MPa or 10 - 30 barand heat at around 220 C for around 10 secondssounds really weird how glass would not crack and handle all that pressure and temperaturei'll post pictures when i canso far i've done the bonding head , transformer , and closed-loop temperature-power system to keep temperature constantnext thing to do is hydraulics and some housekeeping and ironing out the problems and TADA we're in business hhh

author: matseng
author_rank: Frequent Contributor
timestamp: January 09, 2016, 07:23:22 am
content: The guy in this videoseems to be doing what you want to achieve?

author: CaveMannDave
author_rank: Regular Contributor
timestamp: January 09, 2016, 08:05:03 am
content: Quote from: matseng on January 09, 2016, 07:23:22 amSure looks like it, but my audio output is temporarily defunct, so I have to watch the images and add narration in my own head.That's why I didn't watch the other video sooner...Dave

author: CaveMannDave
author_rank: Regular Contributor
timestamp: January 09, 2016, 08:36:16 am
content: Greetings:You probably require a platen (part the glass lays on) that holds it absolutely level, with zero strain when clamped, perfectly smooth (polished?), no burrs, sharp edges, or curvature/twist and no grit.The hot-bar should be similar and contact squarely/evenly and in a smooth perpendicular approach to peak load. The videos I watched implied heat applied as an "impulse", meaning OFF during clamp-up, ON after some delay, DWELL ON for a controlled time, OFF during a cool-down delay phase, then unclamp smoothly.The bar should not be hot at clamp closing or opening.Also, consider the linear thermal coefficient of expansion of the bar material: will it try to stretch or compress the TAB/tape/glass sandwich and leave residual stress in the stackup, that will bite you later?Cheers, and good luck,Dave

author: CaveMannDave
author_rank: Regular Contributor
timestamp: January 09, 2016, 08:52:38 am
content: OBTW, I forgot to take a swing at the ink-on-glass question:As far as I know, transparent traces are some kind of TinOxide process, perhaps fired on in an oven WAY before the stack is laid up. I hope you can use that to search deeper, but I don't have much more info, though my brain is tickling me that some Tungsten compound might also have been used.Make Google your Friend.D.

author: amyk
author_rank: Super Contributor
timestamp: January 09, 2016, 05:50:52 pm
content: https://en.wikipedia.org/wiki/Indium_tin_oxide

author: AhmedAbuShamla
author_rank: Contributor
timestamp: January 09, 2016, 06:16:28 pm
content: for the clamping i'm thinking of leveled 15mm thick glassi don't think it can get any better than glass on glass if they're both parallel to each otherand yes i know all things should be done according to what u said but it all boils down to practicality and what are ur difference between theoretical tolerances and practical ones and getting that down to 0for the thermode i'm using stainless steel 304and thanks amyk for the Iridium_tin_oxide

author: CaveMannDave
author_rank: Regular Contributor
timestamp: January 09, 2016, 10:11:35 pm
content: Quote from: amyk on January 09, 2016, 05:50:52 pmFascinating!Thanks for the clarification.Dave

author: CaveMannDave
author_rank: Regular Contributor
timestamp: January 09, 2016, 10:28:37 pm
content: Quote from: AhmedAbuShamla on January 09, 2016, 06:16:28 pmJust remember, two surfaces of identical composition under compression can sometimes micro-bond/gall/fret one another, and cause stress risers (scratches) in the thin LCDs or roughening of the platen.I hope everything works, in the final design: it sounds worthwhile to save otherwise wasted components.Bravo!Cheers,Dave

author: Bondguy
author_rank: Contributor
timestamp: January 11, 2016, 08:57:46 pm
content: Interesting project.@AhmedAbuShamla: What transformer/ power supply do you use?

author: AhmedAbuShamla
author_rank: Contributor
timestamp: January 12, 2016, 10:55:17 pm
content: @dave stull in the making ..'@bondguy i modified MOT got about 700A@1.7V

author: Bondguy
author_rank: Contributor
timestamp: January 13, 2016, 05:41:22 pm
content: In the past I also tried modified MOT with a similar parameters but during testing ,after very short time secondary became very hot.Do you use any switching power supply or do plug in transformer to the mains directly?What experience do you have with MOT regarding heating ?

author: AhmedAbuShamla
author_rank: Contributor
timestamp: January 14, 2016, 05:59:25 am
content: @bondguyacually this is my first modification to MOT but it seems the bigger the secondery diameter is betteri used 12mm but it gets hot too so i'm going for 19mm diametershould be enough i reckonas for the controller i did a makeshift crude triac control via arduino which does throttle the output but at sometimes it starts making strange things like going up and down like pwm it goes uncontrolabily only when i reach 10% and belownow i'm working on the controller should be done by the end of the day

author: Bondguy
author_rank: Contributor
timestamp: January 21, 2016, 08:08:13 pm
content: @AhmedAbuShamla: Did you already finished the controller?

author: AhmedAbuShamla
author_rank: Contributor
timestamp: January 21, 2016, 08:38:12 pm
content: yes its arduino based computer controllerthe pc controls everything the arduino is like a messanger between pc and everything else

author: Jane
author_rank: Frequent Contributor
timestamp: January 23, 2016, 06:36:45 pm
content: As far as I understand you use microwave oven transformer for your ACF bonding machine. Do you have a problem with the transformer overheating?Last year I tried a similar project but my modified microwave oven transformer became rather hot during 10 seconds when secondary was shorted( alias bonding). Did you solve that problem?

author: AhmedAbuShamla
author_rank: Contributor
timestamp: February 06, 2016, 06:43:39 pm
content: that problem still persists idk what to do about it

author: 4759Sy
author_rank: Newbie
timestamp: January 08, 2017, 09:20:44 am
content: Good night..doyou have arduini scematic ada code?send me olease thanks...