Our FAQ section is updated on a regular basis. If you have a specific question that you would like posted, please email it to us and we'll do our best to include it in our next update. If your question requires a confidential response only, include this request in your email.
Q. We’d like to do in-house tracking of our screens. Does MicroScreen offer a bar code label on their screens?
A. Users of screens and stencils can now request that MicroScreen apply bar code labels. These bar code labels
offer the advantage of tracking for identification, inventory, warehousing, and shipping, to name a few.
The bar codes are scanner and human readable and can be decoded with virtually any barcode reader. The adhesive used on the labels has been tested with the majority of solvents used in the industry with no negative effect.
The bar code symbology used by MicroScreen is Code 39 which meets ISO/EC16388.
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Q. Once we send our Gerber data to you, how do you check the design for aspect ratio and width of apertures,
especially on 20 mil pitch or finer?
A. When we receive your Gerber files, we run them through our EtchGuard software. The software monitors a
number of things, including aspect ratio—the ratio between the size of the aperture and the thickness of the
stencil. For optimum paste release, the preferred aspect ratio is greater than 1.5 and greater than .66 for area
ratio.
In addition, the software checks all apertures to ensure that they are the correct size for a given pitch based on IPC-7525A. If an aperture is too small for a given metal thickness, it is automatically red flagged by the software.
IPC-7525A Stencil Design Guidelines, is available from IPC Customer Service at 847.597.2862 or thru their website bookstore at www.ipc.org
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Q. I am getting ready to send data for a stencil. What is the preferred format?
A. It is extremely important to supply a complete electronic data package - in the proper format.
The preferred format is Gerber with the default being .dxf. These are compatible with virtually all software used in stencil manufacturing, including machine code for laser operation.
OBD++ is also gaining in popularity. Formats with extensions such as pdf, bmp, jpg, or tif are often mistakenly sent as CAD data. These files can show some features of a circuit design, but are not true CAD data. The files can only be viewed as a picture and while they may provide critical information (such as dimensions for panelizing or adding fiducials or rails), they cannot be converted to usable data.
A complete electronic data package containing all board layers will typically provide everything needed for the stencil. Although the majority of the time the solder paste layer and silk screen (component ID) layers are used, fiducials or panels may be shown on other layers and would be necessary for the correct design of a stencil.