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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.

Stencil Tension


Stencil Tension | 24 October, 2004

Hi Everybody, Can someone help me regarding the stencil tension limit standard. We have now in our process 30 ~ 50 N/cm. Is that right?


reply »


Stencil Tension | 25 October, 2004

We assume by "stencil tension" you mean a measurement of how securely [or how tauntly] the stencil foil is held in the stencil frame. If so, we do not know how you would go about making your "30 ~ 50 N/cm" limit measurement when verifying conformance. Is it possible that this tension measurement is an element of your stencil fabrication requirements?

Consider that deflection of the foil of your stencil [under a predetermined load] might be a more practical process control measurement. [Remember that foil thickness and size and shape of holes determines the amount of foil stretch.]

reply »


Stencil Tension | 25 October, 2004

Davef, Thank you for your reply.You are right that I need to consider the tickness also of the stencil. Previously, I take for granted this process of measuring the tension and I usually let my technician do that. However, I have to determine the practicality of the limits. I thought we have a industry standard for this.Are you not doing measurement on your company? Thanks again.


reply »


Stencil Tension | 25 October, 2004

Q1: I thought we have a industry standard for this. A1: We're unaware of such a standard. IPC-7525 - Stencil Design Guidelines has a brief section on stencil inspection. We've talked about it previously on SMTnet. If you can't find it in the Archives [seach], say so.

Q2: Are you not doing measurement on your company? A2: We do not make any similar measurements. We are far more concerned about dinged, damaged, and clogged apertures. Now, we can appreciate that companies with a different volume mix might see a greater need for this type of measurement. [Sometimes well meaning customers sucker their suppliers into doing things like this.]

Maybe we're all wet. [Wouldn't be the first time.] So when your tech measures tension, how does he/she do it? Do you have a written procedure?

reply »


Stencil Tension | 26 October, 2004

Yes, we have an SOP on how to measure. Basically, calibrate the measuring device and measure tension on the 4 sides and one at the center of the stencil. All measurement should be within 30 ~ 50 N/cm otherwise we will not use it and return it to stencil fabricator to fix it for us. I need to check the IPC std you mention and some of the archives also.


reply »



Stencil Tension | 27 October, 2004


Please confirm what measuring instrument do you use on stencil measurement. may we know the brand and website of this instrument.? We also need to measure the sencil tension but we do not have the instrument.

Thank you, Arman

reply »



Stencil Tension | 28 October, 2004

What are the defects you see when the stencil is over 50 n/cm? I can't recall ever seeing a (stencil caused) defect that wasn't a dent, ding or some other physical damage, and I would have a very hard time sending back a stencil that is working fine, just because it failed to meet this highly suspect standard. I can see using this test possibly to troubleshoot a print problem but not as a pass/fail test on each stencil. I could be wrong but I think your valuable time could be spent on other projects that would give a lot more bang for the buck.

reply »


Stencil Tension | 8 December, 2004

try STG-series tension gauge

reply »

24h pcb prototype and assembly

Flexible high speed pick & Place