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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Solder paste amount

You Kim Huat

#4973

Solder paste amount | 16 January, 2001

HI, Can someone advice me, is there any guideline to determince the opening for stencil during stencil fabrication. Also is there any method to determince whether the solder paste amount is enough during this process.

reply »

P.Gerits

#4976

Solder paste amount | 16 January, 2001

Hello,

Standard way to calculate stencil design can be done as follows:

A normal ratio of aperture width/stencil thickness = 1.5 for pitches below 650u A normal ratio of stencil aperture width against pad width = 0.8-0.9 (or stencil aperture 10%-20% smaller as pad width)

Examples: Pitch 650u Pad 380u Aperture 300u Stencil 150u Pitch 500u Pad 300u Aperture 230-250u Stencil130u-150u Pitch 400u Pad 250u Aperture 180-220u Stencil 130u Pitch 300u Pad 200u Aperture 130-150u Stencil 100-120u

In the IPC standard you can find more detailed information regarding this subject

Regards,

Paul Gerits Business manager Assembleon (Philips E.M.T)

reply »

#4990

Solder paste amount | 16 January, 2001

Two good sources of information are: 1 IPC-7525 Stencil Design Guidelines 2 SMTnet fine Archives [once the guys get them back up and running after the conversion is complete]

reply »

George English

#4992

Solder paste amount | 17 January, 2001

You can try : Optimum pad design and solder joint shape for reliability. written for the NPL(England) by Milos Dusek and Chis Hunt, (good ol' English names !!)

or of course the IPC guidelines IPC-7525

Regards

G

reply »

PCB Cleaning

bga rework stations