PCB VIsual Inspection

[Ahmed.Abdulbaky]

Dears,

ok, if I use the Line Scan Camera What is the Cheapest DAQ Which will fit to my application (I found on the NI WebSite  the PXI-1409, is this the one which fit to my Application or there is a variety of Products)

Best Regards 

Ahmed Abdulbaky

[BruceAmmons]

Pick out the camera and lens first, then get the right frame grabber card for that camera.  I suspect a GigE camera will be cheapest for your application when you include the price of the frame grabber.

I would contact Graftek Imaging and have them help you pick out a camera, lens, frame grabber, and lighting combination for your application.  I prefer letting the hardware experts pick out the equipment.

Bruce

[JeffL]

Hi Ahmed,

What kind of camera are you ultimately settling on? If a monochrome analog signal, then yes, then the PXI-1409 card you would want. If you're using a GigE camera, the PXI-8231 would be the way to go. This is assuming you're using a PXI system, of course...

I would highly recommend calling in to talk to your sales rep and they can help you spec out stuff specific to your application.

[Ahmed.Abdulbaky]

see the Attachment, this is a Proposed system to do the PCB Inspection, the Size of the 2X2 Board is 32x24 and the minimum component size is 0.5mm x 2.5mm, so Please check and advice.

as you can see in the attached image, did we need a motor to move the line camera through its area of interest ( the 2x2 board), cause the Line Camera will take Line by Line scan

so did you thinkn that the speed of the motor will be a Factor affecting our Process Time ( 2x2 Board every 2 minutes).

Best Regards

Ahmed Abdulbaky

[BruceAmmons]

It is much simpler to just let the conveyor belt move the board underneath the camera.  The camera stays in a fixed position.

If you are going to use one camera, you need to have it pretty high above the conveyor belt to minimize perspective issues.  Don't forget to double the resolution since my previous comments were based on two cameras.

If your smallest component is 0.5 mm, you might need a resolution of 0.05 mm depending how complex that small part is.  If you need to check the orientation of the part, you will need more resolution than simple edge finding.

Bruce

[Mohammed.Ashraf]

Dear Dr. Bruce, Thanks alot for your support, we really appreciate it so much i have something to add to Ahmed , we are both working on the same project actually. if we used a 1024X1 line scan camera , then we have to make a very small shift to the camera position to scan the next 1024X1 line, i mean a pixel resolution shift. and for example if the camera scanning rate is 27KHz then i suppose to say that we have 27,000 lines per second ? is it possible to move the camera by one pixel (of course i mean the corresponding displacement in real world) to scan the next line properly taking into account the scanning rate ? you mentioned before that there are other techniques which are better than pattern matching , like what exactly ? we have some experience in image preprocessing like histogram matching and equalization, but we thought that after some preprocessing then the road could be paved for an easy pattern matching. also i want to add that the PCBs might be glossy so a direct LED light would probably appear on the PCB image as huge bright circles for example. i'll try to send you a photo for the PCB, i don't think that the SMD components will be with high density on the board as well, but a picture of it will explains alot. final question , according to the SMD package specs and frame (2X2 boards) size , what camera resolution would you recommend , since we are now have a limited budget and we want to construct a demo. we really appreciate your time , your responses and your solutions.. Thanks in Advance Mohammed Ashraf

[BruceAmmons]

The scan rate of the camera is the maximum.  You can scan slower.  I recommend selecting an encoder and attaching it to the conveyor belt.  If you pick the right resolution, you should get the right pulse rate to match the resolution of the camera.

I would put a line light at a 45 degree angle to the surface so it lights up the line that the camera is looking at.  Since it is at 45 degrees, the glossy portion will reflect at an angle and not affect the camera.  Only diffuse reflection will appear in the camera.  You could put a second line light at the other 45 degree angle to balance the light, but that probably isn't necessary.

In some cases, you can do simple tests like average brightness, line profiles, and the sort which are faster than pattern matching.  If you are looking at the orientation of a labeled part, pattern matching is probably best.

I can't recommend a camera resolution without knowing the details of the smallest components.  Assuming everything will work with 0.1 mm resolution, divide the width of the conveyor belt by 0.1 mm to get the minimum number of pixels for the camera.

Putting together a demo is not going to be cheap.  The camera is going to be $3000 minimum, maybe more.  The line lights will be about $1000.  Other hardware is going to be $1000 to $2000, perhaps.  For the demo, you might want to go with pictures from a low resolution camera, but zoom in so the scale is about the same you expect from the line camera.  That will allow you to test/demonstrate any algorithms at the correct resolution.

Bruce

[Mohammed.Ashraf]

Dear Jeff,

we are always in contact with the NI sales Rep here in egypt.

we work as a team with him