Desktop Reflow Oven with Repeatability and Reliability Recommendations? - Page 1
Forum section: electronics / general

author: AJ3G
author_rank: Regular Contributor
timestamp: July 21, 2021, 03:37:48 pm
content: All:I have a need to produce between 150 - 200 PCB's per year which measure approximately 4 x 6". The each PCB will have approximately 150 components on it. I have looked at T962A+ and out of the box I am afraid this will not meet my requirements. I am looking for some recommendations of a Reflow Oven, which has repeatable results, and can follow a profile without significant modification. The material I have chosen for my PCB's is not cheap, and it wont take too many burned boards before paying a bit more for a reliable oven becomes cost effective. Ideally, I would like a desktop model, which could fit two or more PCB's in it at one time. I would also prefer to run the oven from 110 - 120VAC if at all possible.I have consulted google, and I am afraid there is just so much information that it's becoming counterproductive. What I am hoping for is some advice from someone who has done something like I propose above.Thanks in Advance!Rich

author: 48X24X48X
author_rank: Frequent Contributor
timestamp: July 22, 2021, 04:23:04 am
content: I have been using own hacked oven with own controller. It worked very well for 10 years until I started to pick and place faster than I can reflow them. That is when I bought the T-937. It works well in most cases unless you are doing lead free with plastic connectors, then it's tough because in most cases the plastic will melt. So, I used medium temperature solder paste if I have plastic connectors on the design. I wouldn't recommend those smaller ones like T-962. The T-937 has a circulation fan, an exhaust fan and a mini small fan to cool down it's electronics plus a bigger drawer. The temperature reading on the LCD is higher than theoretical curve because it measures the air temperature instead of the PCB. So, the differences is somehow compensated.

author: AJ3G
author_rank: Regular Contributor
timestamp: July 22, 2021, 12:32:55 pm
content: Hello:Thanks for the information. I will eventually be running Lead Free, but for the first runs I will be using lead. I have no problem hand soldering the few components which would be at risk melting.Can you tell me how many profile can be loaded and used with the T937? Have their been any mods you are aware of? From your description I was not clear if maybe there had been like the T962..Rich

author: AJ3G
author_rank: Regular Contributor
timestamp: July 22, 2021, 09:41:45 pm
content: Hi 48X:I just took a look at the spec, and I see this is a 220VAC input system. Unfortunately, getting 220VAC installed in the office space I am in would 10X the T937. I appreciated the feedback however.Anyone have experience with Manncorp?Rich

author: 48X24X48X
author_rank: Frequent Contributor
timestamp: July 23, 2021, 02:27:44 am
content: It can load 8 profile at a time. Quite a number of samples profile is available on their software. It is a far better constructed oven than the smaller T-962. Of course the price is a lot more too. Don't mix your oven usage between leaded and lead free. Stick to one else you will contaminate the oven with lead if your real intend is to sell as lead-free.

author: AJ3G
author_rank: Regular Contributor
timestamp: July 23, 2021, 01:09:45 pm
content: 48X:That is great advice! I had not thought of that. I was going to utilize Lead Solder on the prototype runs because it is easier to work with. The notion that I would contaminate for future Lead-Free runs had not even crossed my mind.Love this board, learn new things everyday!Rich

author: peter-h
author_rank: Super Contributor
timestamp: July 25, 2021, 12:09:34 pm
content: The T962 with the simple external-sensor mod works very wellhttps://www.eevblog.com/forum/manufacture/t962-reflow-oven-233972/msg3614282/#msg3614282Forget the motor+propeller ventilation mod. Just use the temp sensing mod where a thin thermocouple is used right on the PCB.I have no idea whether the standard controller uses just one sensor, or the average of the two, but it doesn't do CJC which is dumb.I reckon to get something off the shelf which works well you have to pay a lot more money. Probably 1k+. The cheap ovens work mostly by luck and will melt bigger components because the radiation heats them up a lot more. The only proper way is a lot more air circulation and decent temperature measurement.

author: 48X24X48X
author_rank: Frequent Contributor
timestamp: July 25, 2021, 02:03:28 pm
content: T937 has 2 thermocouple hanging in the air with a CJC on the PCB. Wish the thermocouple tip can be placed touching the PCB, then it would be perfect. But the program has been programmed to compensate the differences between the board temperature and PCB. I noticed this when I created my own profile on the software where the resulting curve has higher temperature. For me it's perfect except the plastic part for lead free profile.

author: AJ3G
author_rank: Regular Contributor
timestamp: July 25, 2021, 04:48:31 pm
content: Since this will be used to make not only the quantity I specified in this thread, but future board development projects I really cant afford to guess too much. I am looking over some of the more expensive solutions but will see where the specs all fall out.Beyond my repeatability concerns, I am really hoping to find an oven which uses standard 110VAC. This too has proven to be a challenge. I simply do not have room in my assembly room for anything larger than a desk top unit.Based on my research, I think there is a control board modification is on order for the T962 to support temp sensing mod. I could be wrong, but when looking at some of the mods made from users of the T962, that have gone on to sell control board modifications, this seems to be a feature they have incorporated.Rich

author: peter-h
author_rank: Super Contributor
timestamp: July 25, 2021, 05:14:44 pm
content: "Wish the thermocouple tip can be placed touching the PCB, then it would be perfect."Indeed, but the design makes that impossible. The tip would get hit as you close the drawer." But the program has been programmed to compensate the differences between the board temperature and PCB"That's impossibleTry it - with a TC on the PCB. You will be lucky if you get within 30C, and it won't be consistently too high or too low." I created my own profile on the software where the resulting curve has higher temperature."Yes - that is the standard suggestion, but you will spend a lot of time playing around with that, and you will need a PCB which can be wasted."For me it's perfect except the plastic part for lead free profile."LF is a PITA. For small volumes, use leaded" I think there is a control board modification is on order for the T962 to support temp sensing mod"The ES controller works well. It doesn't display a graphical profile but it controls the temp fairly well. I brought out both TC inputs on wires, about 50cm long, as shown in the linked thread, and they go into the drawer via the gap underneath the front of it. The ES controller uses only "A" sensor so the "B" sensor is available for monitoring. I brought both out.The main issue is that the heating is almost totally radiant, hence sensing of the PCB itself works quite well. Some airflow would be great but it isn't easy to do such a mod. The mod I did does work but introduces vibration. The proper mod is a large impeller mounted underneath the heating tubes but this is difficult and messy to do, and would need a slow running motor.

author: IanJ
author_rank: Unknown
timestamp: July 25, 2021, 06:08:53 pm
content: Hi,I use the T-937 with GC10 lead-free paste and I get very repeatable results out the box. My usual load is 6 pcb's covering a total area of 200mm x 180mm and with no apparent hot or cold spots. I've done hundreds of loads.It sits in my main workshop beacuse since it's fitted with an exhaust fan I get very little fumes, if any, into my workshop.The software to create/modify profiles is pretty bad......but it does work and thankfully once the profiles are loaded onto the T-937 it's there that they stay ready for call up.I also have a T-962 which I upgraded with parts from estechnical .co.uk, but it's still not as good as the T-937.......and when I did use it, it filled my workshop with fumes due to lack of proper exhaust fan/vent!Ian.

author: AJ3G
author_rank: Regular Contributor
timestamp: July 25, 2021, 06:56:16 pm
content: Hi Ian:Thanks for responding. I have seen some of your YouTube videos, and enjoyed them very much. If you are using this for the Voltage Reference Boards, than the complexity of those are about on par with the boards I am attempting. I might have to simply wire a 230 - 240VAC outlet into the area where the oven will reside. Normally not an issue, but there is the problem with building management approvals, which tends to do nothing but drive the cost up!Rich

author: peter-h
author_rank: Super Contributor
timestamp: July 25, 2021, 07:36:17 pm
content: I reversed the T926 fan so it extracts - like the recent models from Puhui, which have the duct on the back. Without this, the oven stinks out the whole buildingThe one I got is a non-Puhui copy from UK Ebay; no duct.The fan needs to run slowly though - I set it to 8% - otherwise the heating cannot cope with the cold air coming in. The same issue exists if the fan is blowing air in, of course, but then you don't get any fume extraction.

author: Reckless
author_rank: Frequent Contributor
timestamp: July 26, 2021, 03:58:11 am
content: I would recommend a torch oven or manncorp (usually rebadged torch). If budget was there I'd look at neoden in6 but you may have no need for conveyorized oven. I'd also look at novastar oven. For 200 pcbs you can look at a heat plate.

author: peter-h
author_rank: Super Contributor
timestamp: July 26, 2021, 07:15:20 am
content: Unless your PCBs are double sidedI measured a peak temp of +150C on the bottom, in mine, which should be ok.

author: 48X24X48X
author_rank: Frequent Contributor
timestamp: July 27, 2021, 05:24:03 am
content: Quote from: IanJ on July 25, 2021, 06:08:53 pmI have the same oven and 3D printer as you.

author: IanJ
author_rank: Unknown
timestamp: July 29, 2021, 08:37:32 am
content: Here's my GC10 (type 3 or type 4) lead free profile running on the T-937. This fits the examples in the GC10 datasheet.The cool down cycle is about as fast as I can make it and still keep to the profile........there's only so fast the T-937 can cool down.One thing I've always meant to test and that is the peak temperature accuracy. Need to get the thermal probe in there and map the tray. If I could save a few degC at peak I'd be happier.And here's a board I just reflowed (uncleaned, straight out of the T-937). Nice shiny joints for a lead-free paste!Ian.