PCB_Bird help me Proofread

[ProCarpet]

Hello some of you may remember im building a keybaord (link botom) im done with the case now its atm out for pearlblasting and anodizing. And i want to use that time to finish the pcb which i started.
Im not an electrican or anything close related so im new to this. This is actualy the first pcb i ever designed. Thas the reason why im pretty unsecure if evrything is right/correct.
Now u know why i need the help of this awesome community please proofread the pcb Thanks in advantage ^^.


Software: Altium Designer
For the mc im using a ATmega32U4 TQFP
And the crystal is this one: http://www.distrelec.ch/Web/Downloads/vi/ew/serie%20KX-7_overview.pdf?mime=application%2Fpdf

The points im most uncertain are:
1. The footprint of the crystal
2. The correct connection of the jtag to the mc
3. The Mc
3. The correct capacitors

Here are 2 pdfs 1 with the gnd polygon and one without
with polygon:http://www38.zippyshare.com/v/7412513/file.html
without:http://www38.zippyshare.com/v/1419478/file.html

Here are some pics of the pcb






Here link to the Keyboardtopic: http://geekhack.org/index.php?topic=56279.0

[hasu]

I've used similar type of crystal and it was not easy to solder the component with iron. If you use reflow method with hot air or oven no problem at all, of course. I needed to make pads much bigger to hand-solder it. The reference design of pad in datasheet is too small to touch with soldering iron.

I'd recommend HC-49 type through hole or SMT compoenent instead of FA-238 type because it seems like you have enough space for it.

[dorkvader]

Agreed: if you have enough space, oversize pads for the SMD components will make it significantly easy to solder yourself. Also add some space between components since you have some room.

if that crystal is about the same as the ones on the bpiphany controllers (it looks like it) then it might not be that hard to solder. Reflow would make it easier though You can also pre-heat the PCB and solder it first. I recommend tinning one pad, placing component, reflowing solder with iron, then manually soldering the other pads. I've only done two, but it wasn't so bad.
---
Why not a 32u4 for the uc? It's the one that the teensy uses and so almost all the firmwares are written for it already.

[ProCarpet]

Agreed: if you have enough space, oversize pads for the SMD components will make it significantly easy to solder yourself. Also add some space between components since you have some room.

if that crystal is about the same as the ones on the bpiphany controllers (it looks like it) then it might not be that hard to solder. Reflow would make it easier though You can also pre-heat the PCB and solder it first. I recommend tinning one pad, placing component, reflowing solder with iron, then manually soldering the other pads. I've only done two, but it wasn't so bad.
---
Why not a 32u4 for the uc? It's the one that the teensy uses and so almost all the firmwares are written for it already.

I have an oven for baking will this work to smd solder the parts?
and its a 32u4 lil typo sry ^^ i took this one because you guys use it all the time.
and about the crystal despise having a small footprint is the footprint correct im having troulbe understanding the datasheet. have you a sugestion which i could use instead to make it easy to solder.

[dorkvader]

Agreed: if you have enough space, oversize pads for the SMD components will make it significantly easy to solder yourself. Also add some space between components since you have some room.

if that crystal is about the same as the ones on the bpiphany controllers (it looks like it) then it might not be that hard to solder. Reflow would make it easier though You can also pre-heat the PCB and solder it first. I recommend tinning one pad, placing component, reflowing solder with iron, then manually soldering the other pads. I've only done two, but it wasn't so bad.
---
Why not a 32u4 for the uc? It's the one that the teensy uses and so almost all the firmwares are written for it already.

I have an oven for baking will this work to smd solder the parts?
and its a 32u4 lil typo sry ^^ i took this one because you guys use it all the time.
and about the crystal despise having a small footprint is the footprint correct im having troulbe understanding the datasheet. have you a sugestion which i could use instead to make it easy to solder.

It could work in a normal oven but I wouldn't recommend it.

The reason is that the oven doesn't have good enough thermal regulation to reflow the parts without destroying them via heat.

Here's some info from the datasheet:

So you need to preheat to 150C, then ramp up to ~200C over 150 seconds, then increase the rate to the oven's max and hit 260C, and hold it there for no more than 10 seconds, then shut the oven off and open the door for some cooling (then close the door to avoid thermal stress). I'm sure you can't do that with a conventional oven (that's why DIY reflow ovens have a thermocouple in there with a microcontroller controlling it). You might be able to heat it up so as to not damage the PCB, but I wouldn't count on it as a "sure thing".

Also included is the suggested soldering pad of the crystal. Just eyeballing it on your pictures, it looks compatible, but I don't have any scale or way to measure it. Just check it on your PCB program and make sure it matches. If your pads go further "out" a little, it shouldn't affect things.

As for the exact dimensions, the pads appear to be on 2.3mm * 1.8mm centers and are 1.1mm * 1.3mm in size, according to the picture.

[ProCarpet]

Agreed: if you have enough space, oversize pads for the SMD components will make it significantly easy to solder yourself. Also add some space between components since you have some room.

if that crystal is about the same as the ones on the bpiphany controllers (it looks like it) then it might not be that hard to solder. Reflow would make it easier though You can also pre-heat the PCB and solder it first. I recommend tinning one pad, placing component, reflowing solder with iron, then manually soldering the other pads. I've only done two, but it wasn't so bad.
---
Why not a 32u4 for the uc? It's the one that the teensy uses and so almost all the firmwares are written for it already.

I have an oven for baking will this work to smd solder the parts?
and its a 32u4 lil typo sry ^^ i took this one because you guys use it all the time.
and about the crystal despise having a small footprint is the footprint correct im having troulbe understanding the datasheet. have you a sugestion which i could use instead to make it easy to solder.

It could work in a normal oven but I wouldn't recommend it.

The reason is that the oven doesn't have good enough thermal regulation to reflow the parts without destroying them via heat.

Here's some info from the datasheet:

Show Image

So you need to preheat to 150C, then ramp up to ~200C over 150 seconds, then increase the rate to the oven's max and hit 260C, and hold it there for no more than 10 seconds, then shut the oven off and open the door for some cooling (then close the door to avoid thermal stress). I'm sure you can't do that with a conventional oven (that's why DIY reflow ovens have a thermocouple in there with a microcontroller controlling it). You might be able to heat it up so as to not damage the PCB, but I wouldn't count on it as a "sure thing".

Also included is the suggested soldering pad of the crystal. Just eyeballing it on your pictures, it looks compatible, but I don't have any scale or way to measure it. Just check it on your PCB program and make sure it matches. If your pads go further "out" a little, it shouldn't affect things.

As for the exact dimensions, the pads appear to be on 2.3mm * 1.8mm centers and are 1.1mm * 1.3mm in size, according to the picture.

Ok then a normal oven wont do it ^^.
And i think i got the pads wrong like i dont know if the connections are made correct if pad 1 is up right or where ever.

But since this crystal is hard to mount ill probably want to go with one that goes trough the pcb you have any sugestions like a spescific part?

[dorkvader]

Ok then a normal oven wont do it ^^.
And i think i got the pads wrong like i dont know if the connections are made correct if pad 1 is up right or where ever.

But since this crystal is hard to mount ill probably want to go with one that goes trough the pcb you have any sugestions like a spescific part?

TH crystals are much easier, though I found soldering the microcontroller harder than the crystal.

I would not recommend a TH USB plug, 'cause fine pitch TH can be very difficult. I think the SMD version is actually easier

for the pads, if you look at the datasheet, two of the crystal ones go to the case (I think traces are supposed to go to ground for better shielding, but I dont think that level of paranoia is required.) and the other two (at a diagonal) are for the actual crystal. Since it's at a diagonal, you can mount it either way on the board. Just make sure the topright and bottomleft pads go to the crystal. the topleft and bottomright can do nothing.

Though I think I will have to doublecheck this: I haven't actually made a PCB before. I recommend getting a second opinion or doublechecking yourself before you go get one made.

I just doublechecked the Datasheet and this appears to be correct. I would post a picture of it, but imgur apparently wants to quit working all of a sudden.

edit: here you go:


So the pins that are grounded to the case are attached to one side of a capacitor over to the left there it seems? while the pins that "are" the crystal go to 2 pins on the microcontroller. This may or may not be the configuration you need. Do you have the schematic?

edit2:
Oh this is that build with the awesome case! Sweet! I looked at the other topic looking for a schematic, but wasn't able to find a "good" looking one. Not sure if the xtal1 and xtal2 pins needs the required capacitor or if it has one internally.

[hanya]

C4 and C5 are placed far away from the crystal, they should be placed near the crystal.

[edit] See AVR186 documentation about the crystal layout.

[hanya]

- VBUS (7th pin) is not connected to USB-VBUS.
- AVCC should be connected to VCC even if you do not use ADC, see Pin Descriptions section of the datasheet.

[ProCarpet]

Thank you all for your help
So i addapted the changes here is the current status let me know if theres still something off.

PDF: http://puu.sh/aH2Gx/7955c7a346.PDF

[hanya]

- You should check the usage of PE2 (HWB) pin. But it depends on the boot loader that you are planning to use.
- If JTAG pins are shared with other usage such as the key matrix, it could not fully debug-able while fully functioning. But if you do not need some functions provided by the JTAG, not so problem.
Additionally,
- if you planning to solder straight pins for JTAG, height of the pins are about 8 mm or bit more from the PCB surface. They might interfere with your case. If you choose right angled pins, they cover the screw hole.
- Easy reset-ability if you need.
Sorry for just listing.

[ProCarpet]

Ok then a normal oven wont do it ^^.
And i think i got the pads wrong like i dont know if the connections are made correct if pad 1 is up right or where ever.

But since this crystal is hard to mount ill probably want to go with one that goes trough the pcb you have any sugestions like a spescific part?

TH crystals are much easier, though I found soldering the microcontroller harder than the crystal.

I would not recommend a TH USB plug, 'cause fine pitch TH can be very difficult. I think the SMD version is actually easier

for the pads, if you look at the datasheet, two of the crystal ones go to the case (I think traces are supposed to go to ground for better shielding, but I dont think that level of paranoia is required.) and the other two (at a diagonal) are for the actual crystal. Since it's at a diagonal, you can mount it either way on the board. Just make sure the topright and bottomleft pads go to the crystal. the topleft and bottomright can do nothing.

Though I think I will have to doublecheck this: I haven't actually made a PCB before. I recommend getting a second opinion or doublechecking yourself before you go get one made.

I just doublechecked the Datasheet and this appears to be correct. I would post a picture of it, but imgur apparently wants to quit working all of a sudden.

edit: here you go:

Show Image

So the pins that are grounded to the case are attached to one side of a capacitor over to the left there it seems? while the pins that "are" the crystal go to 2 pins on the microcontroller. This may or may not be the configuration you need. Do you have the schematic?

edit2:
Oh this is that build with the awesome case! Sweet! I looked at the other topic looking for a schematic, but wasn't able to find a "good" looking one. Not sure if the xtal1 and xtal2 pins needs the required capacitor or if it has one internally.

Do you mean something like this: http://www.distrelec.ch/de/Buchse-gewinkelt-mini-USB-B-5-P-W%C3%BCrth-Elektronik-65100516121/p/14257103?q=usb&filter_Anschlussart=SMD&page=3&origPos=1029&origPageSize=10&simi=97.98 ?

[ProCarpet]

- You should check the usage of PE2 (HWB) pin. But it depends on the boot loader that you are planning to use.
- If JTAG pins are shared with other usage such as the key matrix, it could not fully debug-able while fully functioning. But if you do not need some functions provided by the JTAG, not so problem.
Additionally,
- if you planning to solder straight pins for JTAG, height of the pins are about 8 mm or bit more from the PCB surface. They might interfere with your case. If you choose right angled pins, they cover the screw hole.
- Easy reset-ability if you need.
Sorry for just listing.

- I dont know what you mean exactly is it that i cant use the keyboard while reprogramming?
-no im not planing this becaue it will interfeer with my case ^^ . i only cona use some clamps to programm it and when its done i jsut gona mount it in and use it i wont change things too often so this is ok.
- should i use a pullup between the crystal and the capacitor?

[dorkvader]

Do you mean something like this: http://www.distrelec.ch/de/Buchse-gewinkelt-mini-USB-B-5-P-W%C3%BCrth-Elektronik-65100516121/p/14257103?q=usb&filter_Anschlussart=SMD&page=3&origPos=1029&origPageSize=10&simi=97.98 ?

yep, that's one.

[ProCarpet]

So i havent worked on the project in a while because it got to much stress but now i have some time on my hand which i'll use to complet my project. I overworked the pcb design and would like your opinion on this i also have some questions again ^^
About the main changes:
-No more 90° angels.
-Moved all connections away from the border.
-Replaced the Mc.
-No more double occupancy of the Jtag lines
-Removed Col 16.
-Tried to make everything more clean.

Here is a link to the pdf: http://puu.sh/g0MJq/cb0ac61d3e.PDF

My first question is about the power suply as you can see i will power it via the usb but also over the jtag when programming. So my questions are
1. is every thing connected to +5V that needs to be?
2. is every thing that is connected connected correctly? does it need to be serial or parallel or does it even mater?
3. is C4 / C5 placed correctly? do the need to be betwen the gnd and the crystal?
+5V is marked green


About the J-tag i dont think of soldering in pins ill just clip wires to the holes and programm it once its programmed completly i'm very unlikely to change it again.

without gnd

with gnd


So if you noticed something i havent pleas let me know.