Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

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Rob Moats

#9488

screen printer x axis | 17 September, 1999

HI everyone, We are using a Siemens ap-25 screen printer, in the past we have not had any problems with adhesive placement until a couple of weeks ago. It seems the x axis has decided that it should be set somewhere between .00085 and .00150. Normally the setting is .00035. Everyday the setting seems to change in order for us to get the proper glue placement... Has anyone had this problem before?

Thanks

Rob

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Earl Moon

#9489

Re: screen printer x axis | 17 September, 1999

| HI everyone, | | We are using a Siemens ap-25 screen printer, in the past we have not had any problems with adhesive placement until a couple of weeks ago. It seems the x axis has decided that it should be set somewhere between .00085 and .00150. Normally the setting is .00035. Everyday the setting seems to change in order for us to get the proper glue placement... Has anyone had this problem before? | | Thanks | | Rob | | | Not on your equipment, but on others. Please check mechanism and/or stencil setup. Mechanism could be experiencing runout as bearings wear, etc. If not properly programmed, software could be over compensating.

Earl Moon

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#9490

Re: screen printer x axis | 17 September, 1999

| HI everyone, | | We are using a Siemens ap-25 screen printer, in the past we have not had any problems with adhesive placement until a couple of weeks ago. It seems the x axis has decided that it should be set somewhere between .00085 and .00150. Normally the setting is .00035. Everyday the setting seems to change in order for us to get the proper glue placement... Has anyone had this problem before? | | Thanks | | Rob | Rob: I'm confused:

* I wasn't aware Siemens made printers. Could this be a branded MPM AP25? Is kind of a "clam shell" type printer that has the the frame holding the stencil hinged at the back of the machine? * What is this "x axis" adjustment that "someone has decided that it should be set somewhere between .00085 and .00150?" Is this downstop level? Down stop is machine (print head) dependent. It should be set wipe the stencil clean, but not deflect the stencil when the blades are not above the substrate.

Not knowing what I'm talking about and caring less, a lot of times people print "off contact" with clam shell type printers, because the machine doesn't lift the stencil straight off the substrate, but begins lifting the front and then continues lifting, until the back part of the stencil is off the substrate.

So, may be after you check-out the head, as Moondoggie suggested, you might investigate the mechanism that lifts the stencil from the substrate.

Good luck

Dave F

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Rob

#9491

Re: screen printer x axis | 17 September, 1999

| | HI everyone, | | | | We are using a Siemens ap-25 screen printer, in the past we have not had any problems with adhesive placement until a couple of weeks ago. It seems the x axis has decided that it should be set somewhere between .00085 and .00150. Normally the setting is .00035. Everyday the setting seems to change in order for us to get the proper glue placement... Has anyone had this problem before? | | | | Thanks | | | | Rob | | | Rob: I'm confused: | | * I wasn't aware Siemens made printers. Could this be a branded MPM AP25? Is kind of a "clam shell" type printer that has the the frame holding the stencil hinged at the back of the machine? | * What is this "x axis" adjustment that "someone has decided that it should be set somewhere between .00085 and .00150?" Is this downstop level? Down stop is machine (print head) dependent. It should be set wipe the stencil clean, but not deflect the stencil when the blades are not above the substrate. | | Not knowing what I'm talking about and caring less, a lot of times people print "off contact" with clam shell type printers, because the machine doesn't lift the stencil straight off the substrate, but begins lifting the front and then continues lifting, until the back part of the stencil is off the substrate. | | So, may be after you check-out the head, as Moondoggie suggested, you might investigate the mechanism that lifts the stencil from the substrate. | | Good luck | | Dave F | Yes Dave, you are correct. it is a mpm screen printer. my problem lies in the glue placement on the pcb. the adhesive is too far to the left, even on the pad in some cases. by the x axis offset to a postive .00085 to .00150, has corrected thiissue. however the setting it should be has worked fine for as long as I can remember. Thanks for yours and moonmans advice. I will look closer monday.

Rob

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JAX

#9492

Re: screen printer x axis | 17 September, 1999

| | | HI everyone, | | | | | | We are using a Siemens ap-25 screen printer, in the past we have not had any problems with adhesive placement until a couple of weeks ago. It seems the x axis has decided that it should be set somewhere between .00085 and .00150. Normally the setting is .00035. Everyday the setting seems to change in order for us to get the proper glue placement... Has anyone had this problem before? | | | | | | | Thanks | | | | | | Rob | | | | | Rob: I'm confused: | | | | * I wasn't aware Siemens made printers. Could this be a branded MPM AP25? Is kind of a "clam shell" type printer that has the the frame holding the stencil hinged at the back of the machine? | | * What is this "x axis" adjustment that "someone has decided that it should be set somewhere between .00085 and .00150?" Is this downstop level? Down stop is machine (print head) dependent. It should be set wipe the stencil clean, but not deflect the stencil when the blades are not above the substrate. | | | | Not knowing what I'm talking about and caring less, a lot of times people print "off contact" with clam shell type printers, because the machine doesn't lift the stencil straight off the substrate, but begins lifting the front and then continues lifting, until the back part of the stencil is off the substrate. | | | | So, may be after you check-out the head, as Moondoggie suggested, you might investigate the mechanism that lifts the stencil from the substrate. | | | | Good luck | | | | Dave F | | | Yes Dave, you are correct. it is a mpm screen printer. my problem lies in the glue placement on the pcb. the adhesive is too far to the left, even on the pad in some cases. by the x axis offset to a postive .00085 to .00150, has corrected thiissue. however the setting it should be has worked fine for as long as I can remember. Thanks for yours and moonmans advice. I will look closer monday. | | | Rob |

Rob, Are you using a dedicated tooling work-nest or chucks and dams? Is the board-stop sensor built into the head or do you mount it yourself? Have you been running the same product since the problem started or have you done multiple change-overs?

If you have been doing change-overs on an AP-series MPM I believe you have to install the board stop sensor. This might be where the problem is occuring.

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Scott S. Snider

#9493

Re: screen printer x axis | 20 September, 1999

| HI everyone, | | We are using a Siemens ap-25 screen printer, in the past we have not had any problems with adhesive placement until a couple of weeks ago. It seems the x axis has decided that it should be set somewhere between .00085 and .00150. Normally the setting is .00035. Everyday the setting seems to change in order for us to get the proper glue placement... Has anyone had this problem before? | | Thanks | | Rob | The problem is most likely in the camera calibration. I've never had an AP25 but did work with AP24X's for several years. Everytime we needed an offset to get a print we would automatically recalibrate the camera. We had a "C" tool and used it to align the upward looking and downward looking cameras. We did it so often (every couple weeks) that it became and operator task. Of course we had the luxury of having the same operator on the machine for 5 years. If it is more serious you need to call in MPM and have them calibrate the machine.

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harry

#9494

Re: screen printer x axis | 23 September, 1999

| | HI everyone, | | | | We are using a Siemens ap-25 screen printer, in the past we have not had any problems with adhesive placement until a couple of weeks ago. It seems the x axis has decided that it should be set somewhere between .00085 and .00150. Normally the setting is .00035. Everyday the setting seems to change in order for us to get the proper glue placement... Has anyone had this problem before? | | | | Thanks | | | | Rob | | | The problem is most likely in the camera calibration. I've never had an AP25 but did work with AP24X's for several years. Everytime we needed an offset to get a print we would automatically recalibrate the camera. We had a "C" tool and used it to align the upward looking and downward looking cameras. We did it so often (every couple weeks) that it became and operator task. Of course we had the luxury of having the same operator on the machine for 5 years. If it is more serious you need to call in MPM and have them calibrate the machine. | |

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SP700avi inline smt screen printer

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