Hi check this out! I'm super excited about this. This is the Casio SL 800 credit card-sized calculator and this is the what. As far as I'm aware, the world's only true credit card size calculator in world. There's been quite a few that are the same dimensions, which is the ISO 78, 10 ID 1 sized for those playing along at home.

But as far as I know, it's the only one ever made that actually meets the thickness requirement of art. Not 0.76 millimeters are basically under naught point 8 millimeters thickness. It is truly meets the international standard for credit cards. And yes, it actually works.

It's solar powered. It's only a four banger. Of course, four-banger is. It just means it has basically a full function calculator on it, but it's just a marvel of engineering.

It really is phenomenal and it dates from 1983 and it was discontinued a year or two later. and to this date, I Don't think anyone has ever made one equivalent. And of course, I as you've seen in a previous video, had a bash at making the world's thinnest tada do-it-yourself scientific calculator which is actually the PCB is even thinner than this. This is the micro calc, by the way.

if you couldn't read the front, it's only a naught point five millimeter PCB But by the time you know I Put the very slim coin cell batteries on there and the chip and the micro SD card and the LCD and stuff like that, it's obviously a bit thicker. It doesn't meet the ISO standards, but that was a very cool project. I Can't find my original prototype which has all the stuff soldered on it, but I certainly did get the blank board anyway. that's very cool.

Check it out. Yes, those are capacitive. Our touch buttons on there and the date for those playing along at home. 2009 There you go.

Um, it's an old project. Oh, so this is a true marvel of engineering. It really is like let's go times 10 percent. Yes, it even has Sen H Look at that.

It works and solar-powered It works down to 150 Lux I believe I put my thumb over that and still going. still going that can retain how long can it retain that? Not that I raised it pama. But as far as I'm concerned, although granted I am a Casio fanboy, nobody beats Casio in terms of construction innovation in the calculator market. Sorry - or UHP fanboys, you Ti fanboys.

but nobody beats Casio They've got stuff like this like the famous RC FX 400 scientific calculator watch which I wore for like a decade or something when I was a kid and to me that is still the best watch ever. The CFX are 400 and that's where I got the idea for the micro watch and that was my attempt to make pretty much of the world's only other scientific calculator watch and that was relatively successful I saw quite a lot of those people are still wearing them. Hmm. wasn't that robust.

All off-the-shelf parts Anyway, as far as I'm concerned, nobody beat Casio in terms of calculator construction. You see me do Casio calculator arts hair downs before and they're a marvel of low cost and production oriented engineering. but this one is amazing. Yes, this one is customized and of course Casio would do that.

All of the Tandy slash RadioShack calculators for example, they were all Cassio's but obviously this company ordered enough of them like us like a promo kind of thing so they must have These must have been cheap enough to actually our churn this out. And this wasn't the only look for the SL 800 either. Um, there are different variants of it I believe if I can find a photo, I'll include it. But anyway, I Thought we tear this puppy down and see how they did it.

This is even possible. like is it all melted like melted together? I don't know. it's obviously gonna be a destructive teardown I Hate to do it, but let's give it a go. I Think this is gonna need the scalpel and wouldn't you know it, it's a Friday and if you're following me on to you, would have known that my Takano video capture machine it's not the together itself but Windows 10 did an update and it just screwed up everything.

my Us high-speed USB 3 card now doesn't work So which means I can't capture the bloody high-res high-speed video from the Sugano microscope and I'm just gonna have to I can't do this now under that. So I'm just going to have to do it with the camera here and possibly the macro lens and just some magnifying glasses. Black? Unbelievable, right? Bye boy SL 800 Let's crack into this sucker and see what we can do. now.

that just looks like there's no layering on that at all. Wow So maybe I can start peeling off. you know, the front thing or something, but it looks like you know, like it is like a solid plastic credit card. Unbelievable.

There we go. Can we start getting that off? I don't know. Yes. I'm cutting towards myself, my professional.

It's okay. Hmm. so it looks like there's a there's a film layer on that. There you go.

Oh way-hey do this. We're in. We're in like Flynn know that there's no LCD It's obviously using a ribbon attachment, so obviously the front protective is a protective film and also the covering for that. so or at least for part of it.

I Don't know if we could have accessed the back or not, but certainly I mean we're making making progress. Yeah, let's try and get in here. to the get in here to the switches and see what's what. I Didn't feel any tact honest in them at all.

Tell you what looks like they're They're not a capacitive touch, they are. There's no take I Don't think they're going to be tactile dome, but they are. Look at that. That's your traditional rub like you know.

membrane type our contact in there. There you go. Yep, Ah no. they do have a tiny tactile dome.

Look at that. I couldn't I can't feel that when I'm pressing down on that I cannot feel that tactile dome. but wow that is that is one. Huh? Small it like? well actually is it a dome? I don't think it is I think it's just like a carbon pad or something like that.

but then how do they stop it? just make in contact until you push it. Oh this is almost fun. Now this. ah yeah I Feel bad.

This is a pretty rare, not too common these calculators. but yep for science for engineering, there you go, there are they. I'm not gonna say still not gonna say there domes yet. So I don't think that they are domes I Don't see any dome structure in there at all.

Do you know that's a pad? that's a pad? So no I know I Can see what's happening right? What they've got is they've got this thickness. This is a layer. This is another layer in here so this is a thickness extra thickness layer added so that there's no dome structure on top of this. What they do is it just sits on top and lays a tiny gap.

We're probably talking like 0.1 millimeters. and then when you push down on the button like that, that is enough to overcome the very well-engineered height gap there between what is a flat carbon impregnated pad and the PCB tracks. that is. That's great that is very well engineered.

that would have took them quite a bit to get that right and you know and to avoid any production. You know process variation and things like that to ensure that the buttons don't accidentally make contact. That is great. Oh, this is just immensely satisfying I know I'm destroying a calculator and there's no I Got a tear in one eye and when the other eye is just wide open with excitement.

Love it. This is just porn for engineers. Really is unbelievable. Check it out.

That looks like regular solder mask on there so it looks like we've got a very thin. Well, obviously we need a thin PCB in there. It could be less than the 0.5 millimeter one that I use. Maybe it's you know, 0.4 It's probably not too much under that and that's going to add.

The thickness of the solder mask of course is going to add to your total thickness of this front panel spacer for want of a better word and the actual contacts on the board. But geez this is where you wouldn't want to change PCB suppliers or solder mass or something like that you know you could. You could come a guts or if they change the thickness on you then thing your buttons may not work at all. Well then around this edge here we seem to have some sort of some sort of metal.

It's not. It's no longer at the top of the PCB there and this is all just sort of like flaking off now. Hmm so much for the film. Maybe that's where the name comes from film card because they're using these film they're late building up with film layers? maybe? Hmm.

let's go for the bottom. You see how it would have been trivial for them to you know customize these products and just you know sell them is just really. you know a company, company merch and stuff like that. They probably churn this out for next to nothing and once you've done the engineering they're manufacturing, this would have been I suspect.

Once you have, you know once you've tooled up and everything would have been very cheap to make. Yeah, you can see the multiple layers there. the Casio is actually built and the model numbers built into the lower layer. they're made in Japan By the way, all this stuff's made in Japan and then they could just print this over the top so that is ridiculously cheap to change that for somebody.

No worries, there seems to be some sort of like maybe this metal part is like recessed inside this outer plastic part. So I'm thinking maybe if I scrape off the edge like this, maybe it might like fall apart. perhaps. yeah, that plastic around the outside.

It's just started to crack off. so that's really interesting. It's like it's got a like that in some sort of metal back in. maybe this stainless steel I Don't know.

I've been any way that black surround does seem to like it's gonna like break off. Yep, Yep, there we go. Yeah, that was just some sort of edge plastic on there and it just peeled off in one strip. At the rest of it looks like like it's yes, some sort of metal base.

Weird. Yeah. So all of that is just like once again, like a printed film all on top there. So obviously the chair I mean and what we're after is the main control ship.

There's going to be one chip on there, which will be some form of Bairdi because you know I don't have the thickness that plastic encapsulated really? and why would you bother? And we've seen plenty of that in other Casio constructions as well. So yeah, I think this is why they call it a film cut because it's just built up using films of various layers. Very interesting Wow Well at this point I was thinking maybe why didn't I try and heat seperate these or something. Might have been better.

Yeah I don't know. Perhaps you can see the connections down there for the solar cell and see it on a night? Yet another layer down in there. Bingo. If you have a look in there, you can see the layers.

This has got to be like a stainless steel and Tada There you go. Lift that up. Ahh we are well and truly in like Flynn There we go, there's our tiny PCB Oh this is great. This is great and there it is there.

It is fantastic. Ha ha. Wow There you go. Wow That is why have they got that on top of the top of the chip? Is that some sort of yeah, They've got it on top of these.

Oh wow, What? What Are these pads here? What is what's going on here? They got these pads like this: What are these like caps or something? Are they like making like some sort of single layered film cap or something? Well I've never seen something that thin. I mean look at that chip. Look. it's like you've got like you've got to have like 3d vision to actually see how remarkable this thing is.

But wow I'm just stunned at that. and is that regular? like I presume it's like yeah, maybe like 0.3 millimeter PCB point to like. It's actually a prepreg layer that they use inside regular. You know, multi-layer boards and stuff like that.

So I think they've done it is like a it's definitely not 0.5 I think they're doing like a point. Want in like a point 2 millimeter prepreg board or something - and that chip is like like there's no bond wires that I can see. It seems to go in there. Is it some? and it's not I mean that is completely flat so that is just.

and he's remarkable how they done that. What sort of construction method is that? Anyway, the LCD connections. They're just like a kind of like a regular tab hot bar connection so that's no worries whatsoever. but there's no like glass on top of that.

LCD Of course you wouldn't want to add glass on to this because you know if it easily well a it adds thickness and beers it easily break. When this thing bends this thing, they warn you in the instructions not to actually you know, put it in your back pocket. you're not supposed to bend it, but obviously it's gonna it's gonna Bend a little bit. So yeah, they've got all they've got us like a film.

There you go. Oh look at that. There you go. That's the LCD We've just got the reflective back light.

There you go that. Wow Have you ever seen an LCD that thin? That's ridiculous. Hopefully that gives you an idea of what we're talking about here. Nuts actually.

I'm wondering if this whole thing isn't a flex. it's printed on I like a flex membrane. That would be my that's maybe my guess, might not be a prepreg fiber glass after all. This seems to be another layer there as well.

Wow, that's adding to the space in between the the tracks and the button on top as well as the one we've already peeled off. All right, let's peel off this back layer. There we go. It's another thin stainless thing.

Oh, there we go. There we go. We can get the back of the back of the board. Now there's our chip.

There's no silicon. all right Now we're getting somewhere. Wow All right. So there's the back of the die.

You can see how it's been sawn off. You can see the bare silicon in there and but how that's connected on the top is very interesting. I Don't think it's a flip chip arrangement. Hmm.

I Love the colors. That beautiful. All right. We're getting down to the to the last layer here.

So if I peel off the top, peel off the top. There's a solo. so part number. so those playing long homered is an amorphous cell.

There it is extracted that Wow Let's just break that off. Oh, there we go. That was the contact. They've just got the conductive glue with the Flex on there to get over to the solar solar cell.

Wow There you go, we are down. Now down to the PCB there that it's that doesn't feel like fiberglass. To me, that's a membrane. They've done that as a membrane board and which you'd expect.

Of course you could have done it with fiberglass though. You can get really thin prepregs, no problems. So that's basically what they do here. They start with a membrane add membrane PCB like that and you can tell it's a membrane.

PCB although I have used a prepreg before for really thin stuff and it does actually Bend like that, but this looks like it's a like a flat flex. PCB State of the art for 1983, isn't it? And they're basically I have a that looks like they've done a cutout there to embed the chip in there. That's how they get the thickness down so that's the back of the chip. still not sure how they're actually connecting there have put some sort of you know, layering over that and then on top of that they've got the solder mask layer of course, and then they've got the some extra you know, some sort of you know, plastic eye spacer layer in there.

you can see that and then they build up another layer with the stainless steel like that and then the buttons go on top of that and they've engineered the distance to be exactly right. So you just have to press down on that button and there's enough you know curvature in there to get your finger in there and push it down in for the pad to make contact. So that's beautiful. and then they just put am what looks like a um, stainless shim on the back of it as well.

So they glue all that together and Bob's your uncle. You've got the world's thinnest calculator less than our point. Eight millimeters to meet the ISO 7810 thickness standard. That is absolutely brilliant.

I Still don't know what's going on with these things though. and that green stuff on the back of there anyone? Bueller Bueller And that stuff is dangerously flakey. So yeah, I'm guessing that these are actually caps. I Think they actually they've actually made these caps integrated.

Of course, you know you couldn't use regular caps. The high did absolutely kill you. Maybe you could have done it with like a recess cutout or something, an ultra low-profile cut. but I think they've engineered their own caps in there to do that.

So that is. that is remarkable. So maybe you know maybe the black stuff is the dielectric? Perhaps that's why it's all flaking off it really sharp. I've gotta wear eye protection because this stuff is just like flicking up into my face when I actually get it out.

So yeah, I think that's what they've done has actually created their own that film cups in there? Wow Hang on. I think I see what's going on here? Look at this. You can see that these are almost like little world points. Look at that.

so they've actually got it's. It's like a lead frame assembly. There's our chip in there I'm actually able to scrape out I can actually see the top of the bare die in there? Maybe I can get that under the microscope my other microscope and try and have a look at that. but yeah, I'm probably scraped a lot of it now with the scalpel dull.

but I think this is like a lead frame assembly. like a custom lead frame assembly in this and this black gunk and there's clear gunk on top of that and that. Just and they just like weld it in place and that connects over probably conductive glue that connects down to the dye. The dye has the connection points all the way around there and they align up and put this lead frame assembly which connects the bare die on to the that connects it over to the traces and that is.

That is brilliant. Absolutely brilliant. Hats off. Okay, please excuse the crude D of this model.

Didn't have time to build it to scale or to paint it. Ah, Tigana is not working. So I've got my Olympus microscope set up here and we can actually see the dye down in there. so let's actually go in a little bit closer, shall we? Let's get some focus there we go.

Feel that Bobby does LA and is that some sort of I don't know ALU Arithmetic logic unit array I Don't know why how obviously haven't scraped off all the the sort of like the potting. It's a very like it's a gel type arm soft potting compound on there so I could actually skirt and technically scrape it all away. But anyway, we can see some of the detail on the dye in there. and if we go up to full magnification which I think is it's at 400 times I can't remember.

but yeah, the stage is touchy. The stage is the platform that it's that's sitting on. That's okay once we get in there, but you can see all the metallization. You can see the jumpers going over there and info it like.

usually there's markings and stuff like that on there. I Can't find anything like that yet. probably have to scrape off more of the gunk, but I'm probably going to damage it in the process I suspect you can see that black. There's black cotton potting compound and then there's the lead frame.

Okay, scrape to a bit more of it away now. so we should be able to go in there and have a squiz that's terrible magnification mirror and see what's that over there gap scene. There Is that a big memory array? Yeah. memory array.

There you go. that's off to that side there and you can actually see maybe there's connections to the lead frame There those big things. There are the lead frame connections. Whoa.

Yeah, you can see the difference in the layer there as I've scraped that off so there's still some gunk on top of there. There we go have a look at that. I Really love the colors. you can see the where there's clearly still some of that.

crap. Well, that's where maybe I've actually scraped off a layer, another like a coating on top of the silicon die there or something. Oh, that's like a base. Yeah, it could be some sort of lacquer or something on top of the die.

I'm not exactly sure what cuz I obviously got my scalpel across there I've been pretty medieval here. Yeah, you can see another big scrape mark of mine. my scalpel. that's pretty hard.

My apologies for you dye aficionados who think this is sacrilege and I should have used the fuming nitric acid or something to get rid of anything. anyway. I can't see any like and sorry this is not on a flat surface ever I've had to raise it so gotta continually adjust my focus here. Anyway, let me see if I can find a lead frame.

Check it out! You can see the different layers there as I focus that that that's out towards the side of the encapsulants and the lead frame? Nice. Yes! I Know my battery's running low. Yeah, so you can actually see the lead frame connections now. I can bring the top of those in focus and then focus down to the dye level that so you can see some nicer nice detail on there.

I Love the different colors I Love how the light refraction reflects off the various layers of dye. Really is quite something to look at I Hope you are found that interesting. We can actually see get through the dye itself, just a soft and capture one on top of that which is really interesting. Then it seems to be like a harder blacking capsule and around the outside that tends to flake off and it's really difficult to get into those lead frames.

So it looks like they put a black harder encapsulants poxy a capsule and around the lead frame, wires or contacts. They're not actually bond wires, it's just like a lead frame formed lead frame and then sort of like a spot welded in place on the die and on the flat flex as well by the looks of it. So that's how they've done it and then they've just um for protection. I Guess they've just put a little bit of soft encapsulants, soft gel typing capsule, and over the actual dye itself.

Oh, I just got battery exhausted and it's gone anyway. If you want to see the rig, there it is you go. That's the Olympus microscope reed. You've seen this before.

I'm not using the eyepiece and then I'm just using my Sony E-mount camera and I've got a point five our reducer, lens and barrel adapter. This just this just comes out. oh that just lifts out like that and attaches to the Sony E-mount and I'm just doing the HDMI capture from that. But I could also I record locally in the camera too if I wanted to.

So there you have it, that is what's left Cassio SL 800 True credit card size. not only size but also thickness. meets the Iso standards. Awesome credit card calculator and as far as I know if nobody else has ever made another one that's actually as thin as this.

If you know, please let us know. But isn't that fascinating? They've got the flat flex board and the construction of the custom lead frame for the chip. the it what looks like our integrated capacitors on there cuz they're like there's no other passive R components on there. so they've obviously integrated some caps on there and they're ridiculously thin.

LCD Look at that. It's fast, it's absolutely fascinated, and there's no glass. It's just like the plastic polymer type thing. it's sandwiched in there classic Bond hot bar attachment on there and I love how that they did the keys on this.

just like a I'm standoff. I actually had one of the variations of my micro watch design actually used a similar sort of thing with like a raised I was using a PCB like a point five millimeter thicker PCB just like I was on the micro calc here and I was using that as like to get some distance for a membrane overlay using surface mount very low profile surface mount tactile dome switches. So I was doing a similar thing but not to this sort of you know thinness scale. I guess you could call it that's really remarkable bit of Engineering from Casio and as I said I reckon Casio are the world leaders in this sort of you know calculator, packaging technology and stuff like that I Still wish I had my CFX 400 Scientific Calculator watch, but I can remember taking that apart but that was might have come to think of.

It might have used a similar technique because there was no tactile feel in the CFX 400 keypad from memory. Anyway, they're ridiculous expensive now you can't actually get one. Even a broken one is like for 500 bucks on eBay Crazy and and these are actually fair I think recently rare as well these SLR 800 and sorry I had to destroy it I'm as much gutted as you are, but I had to find out and that is absolutely remarkable engineering. Hats off to Casio If you know anyone who actually worked on the design of this sort of stuff at Casio please let us know anyway I Hope you'll like that.

If you did, please give it a big thumbs up because that was I Reckon that was a real interesting night. Tear down and as always discussed down below and you can support me on Patreon and with cryptocurrency and all that sort of stuff always links down below. Catch you next time.