Semi-Automatic Stencil Printing of Fine Pitch

I use a Transition Automation Semi- Automatic stencil printer with laser cut frameless stencils. My solder paste is an SN63/PB37 RMA 291. I do not operate with in a controlled humidity enviroment. The room temp generally runs around 70 deg's but humidity can vary with the swing of a New England day. My problem is the clogging of fine pitch apertures after 4 0r 5 boards, if printed one after another. If there is a time delay say 15 minutes its every board. This causes the need to break down and clean the stencil frequently. Any suggestions.

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| I use a Transition Automation Semi- Automatic stencil printer with laser cut frameless stencils. My solder paste is an SN63/PB37 RMA 291. I do not operate with in a controlled humidity enviroment. The room temp generally runs around 70 deg's but humidity can vary with the swing of a New England day. My problem is the clogging of fine pitch apertures after 4 0r 5 boards, if printed one after another. If there is a time delay say 15 minutes its every board. This causes the need to break down and clean the stencil frequently. Any suggestions. | I've been too spoiled the last few years using under screen cleaners programmed for fine pitch at about two print cycles. Five cycles for less than fine pitch. Sounds like your cycle, with manual cleaning, works as well though labor intensive.

Earl Moon

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| | I use a Transition Automation Semi- Automatic stencil printer with laser cut frameless stencils. My solder paste is an SN63/PB37 RMA 291. I do not operate with in a controlled humidity enviroment. The room temp generally runs around 70 deg's but humidity can vary with the swing of a New England day. My problem is the clogging of fine pitch apertures after 4 0r 5 boards, if printed one after another. If there is a time delay say 15 minutes its every board. This causes the need to break down and clean the stencil frequently. Any suggestions. | | | I've been too spoiled the last few years using under screen cleaners programmed for fine pitch at about two print cycles. Five cycles for less than fine pitch. Sounds like your cycle, with manual cleaning, works as well though labor intensive.

If you don't feel that your paste is drying out you may want to be sure that your stencil is 1) electropolished or 2) not violating the 1:1.5 Aspect Ratio rule (ie. .006" thick foil should have no apertures smaller than .009" wide). | | Earl Moon |

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Mark,

I had the same peoblem. For my stencils i use a 15% reduction for the width of fine pitch leads only, as Earl said follow the 1:1.5 standard. We consider pitches of 32mil and under. We also clean the stencil every other board to ensure no caking. My operators love me for that one. Paste isnt usually a problem but i like to add a little fresh paste every 2-3 hours. Stencil more frequently, and or stir your paste on the stencil after a long wait. I can think of a hundred more things but this may help. Good Luck.

Wayne Sanita

I use a Transition Automation Semi- Automatic stencil printer with laser cut frameless stencils. My solder paste is an SN63/PB37 RMA 291. I do not operate with in a controlled humidity enviroment. The room temp generally runs around 70 deg's but humidity can vary with the swing of a New England day. My problem is the clogging of fine pitch apertures after 4 0r 5 boards, if printed one after another. If there is a time delay say 15 minutes its every board. This causes the need to break down and clean the stencil frequently. Any suggestions. |

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| | | I use a Transition Automation Semi- Automatic stencil printer with laser cut frameless stencils. My solder paste is an SN63/PB37 RMA 291. I do not operate with in a controlled humidity enviroment. The room temp generally runs around 70 deg's but humidity can vary with the swing of a New England day. My problem is the clogging of fine pitch apertures after 4 0r 5 boards, if printed one after another. If there is a time delay say 15 minutes its every board. This causes the need to break down and clean the stencil frequently. Any suggestions. | | | | | I've been too spoiled the last few years using under screen | cleaners programmed for fine pitch at about two print cycles. | Five cycles for less than fine pitch. Sounds like your cycle, with manual cleaning, works as well though labor intensive. | | If you don't feel that your paste is drying out you may want to be sure that your stencil is 1) electropolished or 2) not violating the 1:1.5 Aspect Ratio rule (ie. .006" thick foil should have no apertures smaller than .009" wide). | | | | Earl Moon | | | | Can you tell me how automatic under screen cleaners work and what types of equipment have this feature?

Mark

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I use a Transition Automation Semi- Automatic stencil printer with laser cut frameless stencils.

Just out of curiosity, who's holding the market for the semi-automatic screen printers these days aside from Transition Automation? I know MPM offers some printers in that price range, but are they holding any real market share in that niche?

DEK and MPM seem to have the lion's share of the mid-range to high-range automatic market with some presence of Fuji and Panasonic, and Elite appears to hold court in the manual end.

Just a curiosity as I try to weed my way through this ever changing (and relatively incestuous!) business.

Jennifer

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