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Re: Srceen Printing control parameters

Felix Mung

#10192

Srceen Printing control parameters | 12 August, 1999

Hello,

Can any netters suggest what critical parameters should be considered & what are there assoicated impacts for a solder paste printing process ...

B.Regards, Felix

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Brian Wycoff

#10193

Re: Srceen Printing control parameters | 12 August, 1999

| Hello, | | Can any netters suggest what critical parameters should be considered & what are there assoicated impacts for a solder paste printing process ... | | B.Regards, | Felix | I have a process cause and effect diagram for the entire printing process that I developed. If you would like a copy, send me your e-mail and I will e-mail it toyou. It is in Visio format.

Brian

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#10194

Re: Srceen Printing control parameters | 12 August, 1999

| Hello, | | Can any netters suggest what critical parameters should be considered & what are there assoicated impacts for a solder paste printing process ... | | B.Regards, | Felix | Felix: There are some 30 variables that affect SMT solder quality. 60 some percent of solder defects are caused during printing. The stencil printer is the most important variable in printing paste. It must provide:

� Adequate positioning capability. � Mechanical stability. � For consistent and accurate set-up. � Ability to lock the operator out of certain operations.

Other contributing factors are:

� Circuit board design. � Stencil design. � Paste selection.

In the past, a single printer set-up could be used for all boards. Today, we use experiments to determine stencil printer process set-up. Key variables are:

* Downstop level is machine (print head) dependent. It should wipe the stencil clean, but not deflect the stencil when the blades are not above the substrate. * Metal blades provide more controlled and consistent print height across the entire board than urethane blades. * Squeegee pressure varies according to the selected squeegee blade length and material type. Pressure should be adjusted for both complete aperture fill and stencil cleaning. * Squeegee speed are determined primarily by the solder paste being used. Adjust speed so that the paste rolls in front of the squeegee blade.

So after selecting a printer, squeegee blade, and paste; pressure and speed control the print with pressure having 4 times the effect of speed.

Good luck

Dave F

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Felix Mung

#10195

Re: Srceen Printing control parameters | 13 August, 1999

| | Hello, | | | | Can any netters suggest what critical parameters should be considered & what are there assoicated impacts for a solder paste printing process ... | | | | B.Regards, | | Felix | | | I have a process cause and effect diagram for the entire printing process that I developed. If you would like a copy, send me your e-mail and I will e-mail it toyou. It is in Visio format. | | Brian |

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Felix Mung

#10196

Re: Srceen Printing control parameters | 13 August, 1999

| | | Hello, | | | | | | Can any netters suggest what critical parameters should be considered & what are there assoicated impacts for a solder paste printing process ... | | | | | | B.Regards, | | | Felix | | | | | I have a process cause and effect diagram for the entire printing process that I developed. If you would like a copy, send me your e-mail and I will e-mail it toyou. It is in Visio format. | | | | Brian | | | Hi Brain,

Can you send it to Fmung@smtnet.com ??

I don't have the Visio. So, can you make it in other format such as PDF, doc, xls. etc. Thanks

Felix

|

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Brian Wycoff

#10197

Re: Srceen Printing control parameters | 19 August, 1999

| | | | Hello, | | | | | | | | Can any netters suggest what critical parameters should be considered & what are there assoicated impacts for a solder paste printing process ... | | | | | | | | B.Regards, | | | | Felix | | | | | | | I have a process cause and effect diagram for the entire printing process that I developed. If you would like a copy, send me your e-mail and I will e-mail it toyou. It is in Visio format. | | | | | | Brian | | | | | Hi Brain, | | Can you send it to Fmung@smtnet.com ?? | | I don't have the Visio. So, can you make it in other format such as PDF, doc, xls. etc. Thanks | | Felix | | Felix, I tried to send it via your e-mail, but it came back with erros a couple of times. I created it in the current Visio (5 I think), but where I am now does not have that Visio version yet, so I cannot open the file. When I can, I will try to save it and send it in another format.

Sorry for the inconvenience. Brian Wycoff

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