Tag: Saturday Night Science

How to Build a Computer 14: Alignment


Last time we saw how you physically expose a panel. That is, how you shoot it with ultraviolet light to get a pattern into the stuff so that you can do things to that pattern later on. Today the plan is to talk about all the ways this can go wrong. We’ll start with the big one: alignment. If you’ll recall the profile of the jumping trace we looked at a couple weeks ago:

Hooray for a well-stocked media library!

How to Build a Computer 12: Exposing


We know how photoresist works and how to get it on your material. Or my material rather; most of you aren’t going to be running laminators but no matter. How about transferring a pattern to the photoresist? That’s what we’re going over today. To change the photoresist you’ve got to hit it with an ultraviolet photon. Here, let me demonstrate:

A chunk of photoresist with a bunch of common engineering tools on it. Especially the fez.

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We’ve seen how photoresist works, now we’re going to see how that actually works in the real world. Before you can print things with the patterns you draw in your photoresist you’ve got to draw those patterns. Before you can draw those patterns you’ve got to stick your photoresist on there. Today we’re going to […]

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How to Build a Computer 8: Organic Chemistry


I started with a discussion of the magic of photoresist, however (say it with me!) it got long-winded and I cut it down to the organic chemistry review. Next week photoresist. This week we’re going over some basic organic chemistry. Sounds fun, right? It’s going to be even more fun than that! You wait and see. We’re going to start small though, with methane.

You smell something? No? It’s probably just me.

How to Build a Computer 9: Photoresist


We’ve just got off a quick overview on organic chemistry. Now we’re getting back to photoresist. The point of photoresist, if you’ll recall, is to take a pattern so you can print stuff on your wafer. To do that it has to be a chemical that responds to ultraviolet light. And I mean more “responds to” than get a mild sunburn; it’s got to chemically change so you can transfer the pattern of light into a pattern of stuff.

It’s a polymer made of benzene rings. Someone’s showing off.

How to Build a Computer 7: Patterning


We left off last time discussing circuits and logic and how to make your transistors do something useful. Fun stuff, but I wanted to swing back through a bit more of the manufacturing details. Let’s say I’m trying to make this circuit:

Don’t be fooled by the clever marketing; this is an OR gate with a NOT gate stuck on its nose. Wake up sheeple!

How to Build a Computer 6: Simple Transistor Circuits


The problem with simple transistor circuits is that any circuit with a transistor in it isn’t all that simple. And frankly, I don’t know how much you know about circuits; I’m guessing it ranges from “nothing at all” to “teach your grandmother to suck eggs why don’t you.” At the risk of boring the latter crowd we’re going to give this a slow and superficial treatment. Let’s start with a circuit that’s just about as simple as I can make it. So simple it doesn’t even have a transistor in it!

I’d make this circuit more interesting but I don’t know the symbol for ‘electric chair’.

How to Build a Computer 5: Fundamental Chemistry


I know I promised simple transistor uses last time. Thinking about it though, I’d rather go into a bit more detail about the electron golfing I described earlier. It’s a neat analogy, but it doesn’t cover some things you can do with diodes. Interesting things. Therefore we’re gonna dive in for a deeper understanding of chemistry, atoms, and cartoons. Let’s look at a model of an atom using common household objects:

You all have your Ricochet mugs, right?

How to Build a Computer 4: Diodes and Transistors


We all love blasting things with ions, and most of us could spend all day shooting at wafers, but eventually someone is going to ask you to build something useful. What am I doing with all this mess of silicon anyhow? Here’s where we see the use of all that stuff. What do you suppose happens when you put a p-doped chunk of silicon next to an n-doped chunk of silicon?

One last cookie photo, then I’m going on a diet. Swearsies.

How to Build a Computer Part 2 of N: Crystallography


Last week we saw how to turn sand into silicon. This week I was planning on showing you how to turn silicon into a semiconductor. I mean more of one than it already is. Unfortunately my brief notes on crystallography went long. This week we’ll discuss crystals, next week we’ll do doping, and the week after that we’ll finally get to transistors. Unless I wax even more loquacious, which is the way the smart money is betting.

In a crystal every atom is slotted neatly into an ordered lattice, and every spot in the lattice has an atom in it. With some exceptions. Actually those exceptions are most of what we’re going to talk about today. Let’s assume this is a perfect silicon crystal:

How to Build a Computer, Part 1 of N: Silicon


As the illustrious @JohnWalker no longer treads these halls, I figured there was an opportunity to thrust my metaphorical booties into his clodhoppers. I’ve been kicking the idea of this series around for a long time. Broadly speaking it covers everything you need to know to build a computer. Everything. Today, we’re going to learn how to make silicon wafers.

He’s Gone Silicon

How to Crack Excel Files


This all starts with Mike Mahoney. Mahoney was the Excel guy, two Excel guys ago. To his credit, he wrote pretty good stuff. His macros don’t break often. Everything would have been cool except he was writing these things when Excel 2003 was the hot new thing. Mahoney was also excellent about locking things down from accidental damage. Trouble is, nobody remembers his passwords. Breaking through his protections makes an excellent case study on how to secure and how to bypass the security on an excel workbook.

Not even swordfish works.

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Putting in a quick note for those of you missing out on your weekly Saturday Night Science due to the Annual Week of Rest. Several weeks ago as you no doubt recall, anonymous put up his weekly Saturday Night Science discussing Fab Labs. Briefly enough the promise of a fab lab is a place where […]

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