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MSP430 Reflow Oven


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Really cool. Project. Sorry in advance for some very stupid questions :oops:

 

I wonder about something. I'm using a hot plate to solder SMT components. What are the advantages with an oven?

 

And I also wonder about the soldering profile. Could one just put the board into an oven, keep it there a bit and then take it out? Does one need the heating profile?

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Hey all, Nate here, made a nice little reflow oven to help me in the construction of surface mount boards. Got a video explaining it all here: PCBs and Control Boards for sale here: viewtopic.php?f=

Hello friends, I built a garage-made* SMT reflow oven in 2003, used a simple glass NTC as temperature sensor.   (*) we don't do those things inside "home", it is really made in the only place wife a

Just an update on this since I have not posted in a awhile. I did a second version of my reflow oven with an IR oven and a solid state relay. With this, I could ideally implement a better profile. You

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I'll be using a solid state relay for safety reasons.

 

I thought electromechanical relays were preferred for safety because they can be setup to fail open(Normally Open) while SSRs and SCRs can fail closed?

 

As was stated, the elements respond slowly so using something like a low-cost SCR for power control should be more than adequate. That's how I was planning on doing it but with a mains cut-off relay for extra safety when a program isn't running. I've been wanting to build one of these for a while and this might just be the push I need!

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I'll be using a solid state relay for safety reasons.

 

I thought electromechanical relays were preferred for safety because they can be setup to fail open(Normally Open) while SSRs and SCRs can fail closed?

 

I second that question.

 

I wonder about something. I'm using a hot plate to solder SMT components. What are the advantages with an oven?

 

With a reflow oven that is temperature controlled, you can ensure to a decent degree that your components do not exceed a dangerous temperature range. For example, some components are "moisture sensitive" and thus easily damaged by overheating. However, plenty of people are able to get away with hot plate soldering so its up to the individual. I'm too paranoid rely on that method but its up to you.

 

The profile itself is again to ensure the safety of the part as well as create good solder joints.

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So username... do you want to make a kit out of this. I'm looking to build one for getting 43oh boards done faster.

I can sponsor the first batch of 10 boards. We can organize a group buy for the kit contents.

Win-Win for all. This way we also have a board in the store. You get a percent from the sale of each kit.

 

Anyone else in on this? I need this to be done quickly. I'm putting an order for the OLED boards over the weekend.

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Hey all,

 

I'm honored by your interest. However, unless you guys are willing to pay the price I had in my sales thread I'm not sure your going to be able to build these ovens for any cheaper with a group order.

 

Again, the 2 big spenders(besides the oven) are the cold compensator(15 usd MAX6675) and the K type thermocouple(requires small thermal mass + 400C peak 15 usd).

Combined with all the other components on the board + relay + pcb that is around 45-50 usd. That price really isn't going to change much if we increase the order QTY to 5-10.

 

We would need a cheaper source of thermocouples with a quick response and a high temp rating. I've looked but haven't found any yet.

 

Also the MAX6675 is EOL which is why its so pricey. The replacement is the MAX31855KASA+ (has to be this part specifically for k type) but sadly those are now out of stock on mouser and they won't get any in till 7/1/12 =( . Even if we did get those it would have only reduced the price by 8usd. http://www.findchips.com/avail?part=MAX ... 1228906408

 

At the end of the day, your still looking at a 80 - 100 usd price tag with the oven. As long as your willing to pay around that price range then yea i'd be all in for it.

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- Could you point me to the for sale thread?

- MAX31855KASA - Both Digikey and avnet have it for under $10, unless i'm not looking at the right one.

- K type thermocouple - I'm sure we can couple this into a separate groupbuy

 

Hey Bluehash,

 

Not sure if i'm missing something but according to my lookup on digikey there out of stock: http://oi41.tinypic.com/2rh4w11.jpg

 

regarding the board itself, the raw cost we probably could get down to around 30 usd. (half of that being the cold compensator)

so, 30 usd board + 30 usd oven + 15 usd thermocouple + 3 usd wallwart + 5 usd shipping = ~85 usd at 0 profit

if you sweat some blood you probably could get the board price down to 25usd but i'd be quite difficult.

 

Had a sales thread here but no one expressed interest once I was ready to build. Now those prices are not possible since the MAX6675 is the only SPI cold compensator available.

viewtopic.php?f=22&t=2040

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Ah sorry.. I was one of them. Now I need it :)

You are correct. Everyone is out of the chip. No substitutes at all? There is the ad595, but that's analog.

 

Well, there is still the max6675 which is 14.3 usd I think? Digikey has 5000 of them.

 

Anyhow, the ad595 is 16 usd on digikey so i'm not sure there is value in that unless you can find it somewhere really cheap.

There is also the AD8495ARMZ-ND which is a 5usd analog cold compensator. At this point, the AD8495ARMZ-ND device would probably be the best substitute if one isn't willing to pay for the max6675. However, a complete board redesign would be needed for that device. The reason I choose not to use it because it was not nearly as well documented or esteemed as the max6675.

 

If it is to much to pay the extra 10usd for the max6675 you mine as well revamp the whole board and get rid of the lcd, multiple LSDs(replace with a single bjt),power jack, and headers. At that point you would be able to make it for decently cheap. Probably for about 12usd you could get a board+relay that could run a profile. 12+15+30 +5 = 62 usd.

 

Or perhaps if you all go with the same oven, someone could take timing measurements and attempt to predict temp rise per how long the element is on. If you did that you may be able to eliminate the thermocouple and cold compensator all together but it would be more risky. However, all you would need then is a relay, micro, and a few other basic components.

 

Or... you could try not using a cold compensator and attempt to do that with the msp430 that has a built in temperature sensor. lots of options out there.

 

However, i'm slightly biased towards my features so i'd like to keep them ;) . However, anyone of you are more then welcomed to attempt a cheaper board redesign.

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Hello friends, I built a garage-made* SMT reflow oven in 2003, used a simple glass NTC as temperature sensor.

 

(*) we don't do those things inside "home", it is really made in the only place wife allow us to work on it, the garage, isn't it?

 

[Forum doesn't allow me to post external URLs, it thinks it is spam, since I am a new user... remove the extra spaces below] :eh:

http://www.ustr.net/smt/oven.htm

 

As a sensor, I used a common glass NTC to a small piece of a regular Printed Circuit Board, so it simulates exactly what the real boards are receiving of temperature.

 

You can not use soldered things inside the oven, solder will melt. So I tied to tiny pcb to the oven's grill using rigid wire, and just twisted the high temperature (green) wire to the NTC leads.

 

The glass NTC cost around one dollar. The NTC datasheet says it works up to 150

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