Add-on soldering talk and experience share

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gagadagatika
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Re: MiSTer: MiST on Terasic DE10-nano board.

Postby gagadagatika » Mon Sep 04, 2017 8:32 pm

Hey guys! So, I shipped about 30 orders in the last 1 ½ month and I thought I’ll give you a quick review of how it all went so far. This is the first time that I assembled PCBs for others, so there was kind of a learning curve to me, especially when it came to the logistics. I hope you find this interesting or maybe it is of some help for others who want to make boards in the future.

First Off: It seems that everyone is pretty satisfied with their boards so far and that makes me pretty happy. Some don’t like it that the SDRAM won’t go higher as 140 MHz. That is unfortunately still the maximum I can archive intentionally. I had some boards that would make 150 MHz for 30 Minutes but that was pretty rare (maybe 3-4 Boards). However, no one was mad and all showed great support. Thank you guys!

Logistics:
I shipped initially with a delivery service (DHL), but switched later to a postal service (Deutsche Post). It’s just half the cost and the delivery time seems to be the same. The tracking was still later available through DHL for most countries. Fastest delivery was 1 day 20 Hours inside Germany (surprise!) and longest delivery time (yet) is 12 days 20 Hours to the US. Here is a list of all delivery times so far:

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I started shipping with shipping bags that I’ve bought from a local store but switched then to carton boxes, since it was much cheaper and more sturdy. I've made sure they would fit a regular mailbox (2 cm Height). The boards are also much more secured in it.

Costs:
I did not plan to make a big buck with this since I basically sold them at cost. I have paid overall 571€ so far for two batches of components and utilities and was able to get 600€ back in. This whole project is for me a way to get the necessary equipment, learn how to efficiently assemble PCBs, and to get some experience with international shipping. However, here is a list of all costs I had during the last 1 ½ month:

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I figured that if I want to buy more than 10 PCBs from PCBway or JLCPCB, then it makes sense to make a batch with multiple orders of 10 PCBs. It is much cheaper than just buying e.g. 30 boards in one order. The shipping cost will be the same since it is calculated by weight, but the PCB cost is completely different.

Making the Boards:
My first boards were a mess, I was completely out of practice. I've bought better soldering tips and a cheap microscope, which helped with the soldering. In my second batch, I bought a stencil, soldering paste and a hot-air soldering iron for the SDRAM boards and the results were like night and day.

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The IO Board was a pain. I have ordered the wrong VGA connectors and had to manually fix every pin of the connectors. It was almost a piece of art in the end :D I bought epoxy glue to fixate the connector to the board, which gave it extra stability. You can see it pretty good in this picture:

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I completely underestimated the time It would take to make the IO board. The components are all soldered by hand, which took me about 3 hours per board. I want to make another batch of IO Boards in the near future, but I will order it with stencil this time. I hope that helps a bit. I also figured that it makes sense to buy some components just from AliExpress instead from Mouser or Digikey. Especially the 40 Pin Female Header. Most of the stuff is so much cheaper if bought in some quantities, even with the shipping cost included.


Future:
I’ve made some experience with components over the course of this project and I will update the Wiki soon with a more detailed BOM for SDRAM and IOBoard. People are also asking and I’ve got already enough requests for another round of IO and SDRAM Boards. So, I am going to make another batch and I will make remaining boards available in the Buy / Sell Section.

I have also played with the idea of making an external Button/LED Board which could be mounted to a case. I want to make those to see how well it goes and to make my own experience with PCB manufactory. All PCBs I've have made in the past were created by myself, so ordering PCBs from a manufacturer is still somewhat new to me. The Board is pretty simple but I have to test it first to see if it is something, but here are some pictures of it. Big thanks to NegSol for helping me with this!

Image Image

OK, that’s it for now, this already became a bit longer then I have intended. I hope it did not become too boring :D Thank you again for all the great feedback and support!!!

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Re: MiSTer: MiST on Terasic DE10-nano board.

Postby Sorgelig » Mon Sep 04, 2017 8:58 pm

About buttons: May be it will be simpler and cheaper to use a top surface of case to mount the buttons and LEDs. So you won't need to make additional board. Buttons can be an extenders pushing original buttons on the I/O board.
May be NegSol will help to make 3D models of such buttons.

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Add-on soldering talk and experience share

Postby Sorgelig » Wed Sep 06, 2017 11:56 am

Here you can ask questions about soldering the boards. What tools to use, what components to use, etc.
Also you can share your experience and tricks.

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Re: Add-on soldering talk and experience share

Postby Sorgelig » Wed Sep 06, 2017 12:49 pm

About connectors for buttons and LEDs:
If you use a bare pin connectors like on picture above, then it's advised to remove unconnected pins. They are key-pins. The female connectors need to have this pin sealed, so it will prevent wrong direction. Wrong direction may potentially damage the board.
This is even more important if you make the board for others who are less aware about connectors.
I suggest to use compatible boxed connectors preventing wrong direction.

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gagadagatika
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Re: Add-on soldering talk and experience share

Postby gagadagatika » Wed Sep 06, 2017 3:25 pm

Sorgelig wrote:About connectors for buttons and LEDs:
If you use a bare pin connectors like on picture above, then it's advised to remove unconnected pins. They are key-pins. The female connectors need to have this pin sealed, so it will prevent wrong direction. Wrong direction may potentially damage the board.
This is even more important if you make the board for others who are less aware about connectors.
I suggest to use compatible boxed connectors preventing wrong direction.


I was thinking of using something like this for the connector XH2.54 (AliExpress). They seem to be compatible with yours and foolproof enough :D

I will use these dope LED integrated Tactiles Switches: FSMIJ (Datasheet).

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Re: Add-on soldering talk and experience share

Postby Sorgelig » Wed Sep 06, 2017 3:39 pm

gagadagatika wrote:I was thinking of using something like this for the connector XH2.54 (AliExpress). They seem to be compatible with yours and foolproof enough :D

yep. that's what I'm using. The first pin is on the right if you look at picture on Aliexpress.
4.0+ I/O board need vertical version.

gagadagatika wrote:I will use these dope LED integrated Tactiles Switches: FSMIJ (Datasheet).

Although there are 3 LEDs and 3 buttons, they have no logical relation to each other. But it's up to you.

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Re: Add-on soldering talk and experience share

Postby yellperil » Mon Sep 11, 2017 2:55 pm

Not sure if this should go here, I've successfully soldered my memory board using these tantalum capacitors from element14 (au):

1135082 TAJR104K020RNJ TAJR104K020RNJ CAPACITOR, 0.1uF 20V R CASE

With a vertical position on the universal board the 140 test runs flawlessly, above that it gets unstable.

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Re: Add-on soldering talk and experience share

Postby Sorgelig » Mon Sep 11, 2017 5:59 pm

I'm not sure if it's really tantalum capacitors or not. Usually tantalum caps have much higher capacitance like 22uF and up. For 0.1uF i recommend to use ceramic caps - they are more robust and don't tend to explode (although 3.3V should be safe for any cap).

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Re: Add-on soldering talk and experience share

Postby yellperil » Mon Sep 11, 2017 9:30 pm

Yep that's fine I just got a bit confused as the board has markings that look like they are for polarity? and the wiki had tantalum written on it for a little bit, I see it's been updated. I'll see how they go and change them to ceramic if things break.

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Re: Add-on soldering talk and experience share

Postby TorsteinP » Fri Sep 15, 2017 3:40 pm

I've ordered a hotair-flow tool for SMD soldering. https://www.velleman.eu/products/view/?id=435950
Also a flux pen and soldering paste syringes from digikey.

Never done any SMD soldering only normal old fashion through hole.
Found some nice tutorial videos on youtube. https://www.youtube.com/watch?v=_IjNZc8U5ik
Only waiting for a big box of components from digikey for I/O board and SDRAM board :)

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Re: Add-on soldering talk and experience share

Postby Sorgelig » Fri Sep 15, 2017 8:34 pm

I've used pretty large SMD components, so you can solder them by normal soldering iron.

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Re: Add-on soldering talk and experience share

Postby TorsteinP » Thu Sep 21, 2017 8:32 pm

Hot air soldering is definitely much easier and faster then using soldering iron.

First need to pre-heat the board to around 250 and then use the soldering paste syringe on all soldering points.
Then place all the components. Turn heat up to 350 and guide the hot air pen along the soldering points. After a little while you see the soldering paste turn liquid and contract around the soldering points. Then it's done.

I had a few pins on the SDRAM chip that got to much solder and was sticking together. Just used desolder braid to remove excess solder.

It takes a little practice to get the hang of it. First SDRAM board took me 30 minutes to finish. Second took me only 10 minutes :)


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