Yah 962A works good . But you need to calibrate before using. The timer inside 926A has delay lag of 1.2sec to 1.5sec. Means On the LCD you will be seen the process is running 7-8mins, but in real world the time will be 10-12 mins. Definitely you don't want to over bake your PCBs. So you have to set your temperature profile. Also Heat distribution around the far corners are not same as center area. But I got solder a A4 size PCB panel without any issue. Also we made a custom Zing to hold PCB for Double Side SMT Soldering.
Also for the Above SnBi Solder paste, we manage to set temperature setting after so research and it works very good.
Remember that the device is made for China, so when you want to use in your comfort zone, you have to make necessary modification. We are running micro production of 500-1000 units Boards per month and the reflow Oven is working perfectly over 2 years.
I was looking in D.P forum for setting solution to our IR reflow Oven on Sn42Bi58 solder paste , when I noticed at post viewtopic.php?f=68&t=4903&start=165#p50701 that A.M is using Similar process for Reflow soldering i.e (IR reflow oven + Sn42Bi58 solder Paste) . Now let me explain you in detail about the issue we are trying to fix.
Our IR oven is T-962A similar to QS-5180C from Qinsi Technology . we are using Sn42Bi58 solder paste from Synaptic Tin tin lead-free solder paste (Sn42Bi58 3.0 P/N# UP301B) (Purchase from manufacturer via Taobao http://item.taobao.com/item.htm?spm=a1z ... 517179090# ) Sn42Bi58 3.0 is little bit more smooth/finer than Sn42Bi58 2.5.
Now the problem is, I have never used this Sn42Bi58 paste before, usually I use SAC>SnAgcu paste. So I bought it in January , but stored it in refrigerator as I used previous stock left some SAC paste. Two days ago I open that 500mg pack to test , and surprisingly even after 6 month solder paste is in very good condition/flux constant is also good, because we store it 0-5 C temp. So in order to test this paste I required to set the temperature profile of my Oven. So I set the reflow profile by referring some documents/datasheet for SnBi paste available on internet. After running couple of test reflow process on a sample PCB, I noticed that the paste does not melt even at 160-170 reflow range. when i took out PCb and test the paste, I found that Flux is doing its work at expected temperature but metal part is not. I had used 6-7 different temperature setting for calibration referring the attached datasheets.
So can any member help me to figure out what am I doing wrong with the process. If you need more details on temperature profile I have used on it. let me know, I will share it. Reflow temperature profile that I used as reference are linked below.
Sorry the images are bit out of focus [attachment=5][attachment=4][attachment=3]
let me explain what we found from this test pads.. we found that for 10X10mm pad, machine is drawing 9.7X9.7mm pad with each side has an lag error of 0.3mm , even this 0.3mm error is in every where.. gap between two draw of same line is 0.3mm, line are over crossed with 0.3mm, gaps between end points of draw line is also 0.3mm. please see this image for more clear understanding.[attachment=2] click to enlarge RED,BLUE,GREEN,YELLOW lines are the actual draw line/cutline by machine in the order they crossed,draw gap respective coloured lines, Gray area is the actual 10X10mm pad area in software design/gerber file. similar 0.3mm gap is also experienced in 50x50mm pad and draw line are 49.7mm in length. So after this investigation we were clear there is 0.3mm lag offset error from the machine.
WAIT A SEC....On little push we found that we completely forgot about Blade offset gap from the Cutter. Generally blade offset setting is fed on Cutting software or SW sets default offset setting depending on your blade setting in cutting software. In this case of gerber2graphtec blade offset or cutter offset has to be setup manually into the code. We really don't know how silohuette Studio set it's blade offset, but when we dug into g2g_gui.py and grapthec.py we found the offset option given in GUI is for Media offset, it is not the cutter/blade offset. As blade offset is a fixed value. Then we search for GPGL and HPGL command for cutter offset in this two PDFs provided by Graphtech. [attachment=1][attachment=0] We found they both have a common command for Cutter offset i.e FC p,q[,n] [t] . In graphtec.py it is used as
. Also value of the parameters are unknown for real world conversion. for example in FC18 what does 18 means , is it 18mm or 1.8mm or 0.18mm or something else.
Now the issue is I have very limited knowledge about programing in python. From the codes I can understand the algo and work flow.. but I am not skilled enough in python programing,So I can't code for blade offset parameter into this code. If anyone from this user group can help in that , then we can develop and support all this resource for a non-graphtec plotter platform.
this is a great post , it get us week long stencil outsourcing process on our desktop. After noticing result of other users we took initiative to make it work on other commercially available vinyl plotter. We have a plotter inhouse for some work, but now we tried to make SMT stencils for PCBs. after a 6 days full work on code conversion , calibration we got it work but that is 92% . We have raised some issue during working on the plotter. Let me explain what we have done till now, why it is 92% success, what are the issue currently facing.
Plotter Machine Specification:
Size:24 inch Brand Name: GOLDCUT/JINKA JK721 series Driver:stepper motor Cutter
Paper Feed Width: 720mm Max Cutting Width: 630mm Cutting Length:unlimited Cache Capacity:1-4MB Interface: RS232 / USB interface Control panel: English LCD display cutting material: paper, vinyl
Pro over Silohuette Cameo Silohuette Cameo has 7 grams force per setting and has 33 levels. In other words, the Silhouette can cut from 7 grams up to 230 grams force.
JK721 has 10- 500gs force.
Silohuette Cameo Speed is measured in centimeters per second x 10. In other words, the Silhouette can cut from 10 centimeters per second up to 100 centimeters per second.
JK721 is Cutting Speed: 10mm/s -to 800mm/s
Con over Silohuette Cameo JK721 does not support Graphtech Command at all i.e GPGL . it only support DMPL/HPGL Commands.
In HPGL it doesn't support values after decimal points.
JK721 also does not support software control of velocity/speed and force of PEN/cutter blade. it is totally user defined manual setting on the machine.
2. We modify graphtech.py and gerber2graphtech.py according to HPGL command as our plotter doesnt support GPGL or graphtec command. We made changes in Initialisation , ending, move, draw section. We had to change all float values output to decimal values in result.txt
3.Also made minor change in g2g_gui.py as some paramers will not work on a HPGL based plotter. We modify to send the draw file direct to plotter on serial port ,instead of using windows printer mode. Because we found that most of the time we got printer in queue error when using windows print mode.
4. Also add a step to delete previous _tmp_gerber.pdf each time before we create a new gerber file on gui page. [attachment=3]
After doing this much of things we made it work for HPGL plotter , means we can send draw file from GUI to plotter and machine draw the line as per instruction.
Why it is 92% success? After cutting 2-3 test pad we saw this on the sheet. [attachment=2][attachment=1][attachment=0]
At very 1st we did not find any reason for this error, so we took a different step to investigate. We create a test gerber of cream pad of size 10X10 mm and 50X50mm . created the draw file using GUI and send it to machine. after some 3-4 draw we found what is the issue.
