60 Deg or 45 Deg Blades

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Hi, I always thought 45 deg squeegee blades were the way ... - Mar 05, 2001 by flynhi34

You're correct 45� is preferred. 5 Paste sticking to sque... - Mar 06, 2001 by davef

DEK wrote a paper that compared 45 degree blades vs 60 degre... - Mar 06, 2001 by Jerry Hingtgen

Strange? Can u explain why magnetized squeegee be a factor, ... - Mar 07, 2001 by

Sure, the rolling action of the paste creates a weak magneti... - Mar 07, 2001 by davef

We've actually seen best results with 60 degree blades (as m... - Mar 15, 2001 by Keith47611

flynhi34

#5473

60 Deg or 45 Deg Blades | 5 March, 2001

Hi,

I always thought 45 deg squeegee blades were the way to go for solder printing. What are everyones opinions? Does anyone think that 45 deg blades will help prevent solder paste from sticking on the squeegee blades since equal amounts of paste will be on both the squeegee blade and the stencil.

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davef

#5476

60 Deg or 45 Deg Blades | 6 March, 2001

You're correct 45� is preferred.

5 Paste sticking to squeegee: * Squeegee is heavily magnetized * Some pastes stick more than ... * Plastic squeegees stick more than metal * Old metal squeegees stick more than new * Paste needs to be worked * Paste needs to be at room temperature * Some flux formulations are very sensitive to humidity * Need enough paste for thumb sized roll. Too little & it won't fall off. * Temperature in your screen printer needs to stable. Paste suppliers say that 1� C change can affect paste viscosity by about 10%.

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Jerry Hingtgen

#5481

60 Deg or 45 Deg Blades | 6 March, 2001

DEK wrote a paper that compared 45 degree blades vs 60 degree blades. This paper was presented at APEX 2000 by Jay Hinerman. Email me at jhingtgen@dek.com and I will ensure you get a copy.

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Cosine Theta

#5485

60 Deg or 45 Deg Blades | 7 March, 2001

Strange? Can u explain why magnetized squeegee be a factor, not to mention rusty squeegee?

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davef

#5492

60 Deg or 45 Deg Blades | 7 March, 2001

Sure, the rolling action of the paste creates a weak magnetic field surrounding the paste. This is similar the field created by electric current flowing through a wire, as first described by James Maxwell. After creation of the magnetic flux, the magnetic field collapses and collects on the squeegee blade, because it long and narrow. This is all basic Physics 101, right? I mean, I�ve seen those fields build-up over time to such a level that you could actually see sparks jumping the blade to the printer frame. What is that 2 to 3 inches? That�s some serious ...

[Awww, I�m just spoofin� ya!!! ;-) And Cosine caught me red-handed. See, ya gotta try and sneak stuff like that by ever so often, justa calculate if anyone�s awake out there.]

CAUGHT RED-HANDED � "�To be taken with red hand� in ancient times was to be caught in the act, like a murderer, his hands red with his victim�s blood. The use of �red hand� in this sense goes back to 15th century Scotland and Scottish law. Scott�s �Ivanhoe� has the first recorded use of �taken red-handed� for someone apprehended in the act of committing a crime. Not long after, the expression became more common as �caught red-handed.�" From "Encyclopedia of Word and Phrase Origins" by Robert Hendrickson (Facts on File, New York, 1997), Page 135-136.

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Keith47611

#5587

60 Deg or 45 Deg Blades | 15 March, 2001

We've actually seen best results with 60 degree blades (as measured from stencil surface to face of blade), and paste sticking has not been a problem since we switched to a higher quality metal blade. More expensive than the OEM stuff but worth it. 45 degrees seemed to create too much downard pumping action (which, by the way, was good for paste-in-hole printing but not conventional printing). Good luck

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