C Sys Labs, Inc.

Green technologies today for tomorrow...
3030 Thorntree Dr. STE 6
Chico, CA 95973


(530) 894-7954 voice

tom@csyslabs.com e-mail



Pb Free ROHS compliant circuit assembly

SnPb circuit assembly

Cable fabrication

Product assembly

Failure analysis

Circuit design and prototyping

PCB layout services

Used equipment - use link at bottom

DFM Guides

Assembly of your products can be enhanced by following a few simple guidelines during the design phase of a PCB.


Remember, operators must be able to handle your board during production.  This means small boards should be in a panel having at least 1/4" of frame.  This not only allows handling but also mounting in machines.  Components can be closer to the board edge when in a panel.


Larger individual boards without frames must have components no closer than 0.050 inches from the board edge to accommodate mounting and handling.


Insert alignment targets in the upper left and lower right of your board.  Alignment targets are created using either a 2mm circle of metal without soldermask over it or a butterfly pattern made up of two 1.5mm squares without soldermask.  The alignment targets should be spaced from hole or other geometries by about 2mm if possible.  I recommend that each board in a panel have it's own targets to allow for flexibility when placing components.  The panel may have it's own set of targets as well.


Minimize cost of assembly.

SMT parts on one side of a board is lowest cost to assemble.

SMT and Through hole on the same side are the next level of cost.

SMT on both sides is the next higher cost.

SMT on both sides plus through hole on one side is higher yet.

SMT on both sides and through hole on both sides is the most costly to assemble.

The reason is simply the number of operations required to complete the job.  Each more complicated level requires more operations, operators, equipment and mostly time.



Stencils should be 5 mils (0.005") thick and metal.  Unframed stencils should measure 12"x12" and should be used for prototype small boards only.  Framed stencils come in standard sizes.  The most compatible with our equipment are;

12"x17" cast frame

15"x15" cast frame

23"x23" cast frame

23"x23" extruded frame

Remember that the long dimension of the print area needs to also include about 3 inches of takeoff and landing space for the squeegee start and stop.  Your data should alwas be rotated to best fit the print area of the stencil.

Apertures for fine pitch parts such as QFPs, TSSOPs, and leadless packages should be reduced in area by 20% to avoid excess solder resulting in bridging between leads.  Keep the shortest length of an aperture to 9 mils as a minimum to help the paste release during printing.  Any center pads should also be scaled to match pad paste reductions to avoid floating and tilting of the package when reflowed.

Most other larger pitch parts can stand the paste apertures being the same size as the pads.

C Sys Labs does offer paste file reviews and gerber file editing prior to creating stencils for your peace of mind.