PCB Stencils
PCB Stencils In the table below is a comprehensive list of Sunstone's key printed circuit board manufacturing capabilities.
PCB Stencils In the table below is a comprehensive list of Sunstone's key printed circuit board manufacturing capabilities.
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Now you can add a stencil to any PCB fabrication order. Simply place your PCB order as usual, and choose from a variety of stencil types and sizes, one to fit each of your stencil requirements.
Need to order a replacement stencil for boards previously manufactured by Sunstone? No problem! Just access the board order via your account order history at any time, and order a stencil directly from your history.
See the chart below for more details on the stencils available.
The sole purpose of an SMT stencil is to transfer solder paste to a bare circuit board. A stainless steel foil is laser cut creating an opening for every surface mount device on the board. Once the stencil is properly aligned on top of the board, solder paste is applied over the openings (making a single pass, using a metal squeegee blade). When the stainless steel foil is separated from the board, solder paste will remain, ready for placement of the SMD. This process, as opposed to hand soldering methods, ensures consistency and saves time. Want so see an example of this process with step-by-step photos?
Stainless steel foil thickness and aperture opening size control the volume of paste deposited on the board. Too much solder paste causes solder balling, bridging, and tomb-stoning. A lack of solder paste creates insufficient solder joints. All of which compromise the electrical functionality of the board.
Proper foil thickness is chosen based on the types of devices being loaded on the board. Component packages such as 0603 capacitors or 0.020” pitch SOICs, will require a thinner solder paste stencil than larger packages such as 1206 capacitors or 0.050” pitch SOICs. Solder paste stencil thickness ranges from 0.001” to 0.030”. The typical foil thickness used on the majority of boards is anywhere from 0.004” to 0.007”.
Now offering nano coating on select stencils and sizes! "Nano coating” is a two part, wipe on process, made up of hydrophobic elements that repel flux and solder, resulting in improved paste release for extremely small components. The coating is applied to the contact side of the stencil prior to shipment, making the stencil ready to use right out of the box. This coating is recommended for fine pitch QFN’s, fine pitch IC’s, micro BGA’s, and 0201 component types.
Solder Stencil types and sizes | |
|---|---|
| Prototype SMT Stencil | Prototype SMT Stencil (up to 10” x 12”), squeegee, and board holder. |
| Oversized Prototype Stencil | Prototype SMT Stencil (exceeding 10” x 12”), squeegee, and board holder. |
| Prototype Stencil Kit- Leaded | Prototype SMT Stencil (up to 10” x 12”), leaded solder paste, pick & place tool, temperature marker (331° thru 379°), 1 pair of gloves, and 2 alcohol wipes. |
| Oversized Prototype Stencil Kit-Leaded | Prototype SMT Stencil (exceeding 10” x 12”), leaded solder paste, pick & place tool, temperature marker (331° thru 379°), 1 pair of gloves, and 2 alcohol wipes. |
| Prototype Stencil Kit- Lead Free | Prototype SMT Stencil (up to 10” x 12”), lead free solder paste, pick & place tool, temperature marker (390° thru 450°), 1 pair of gloves, and 2 alcohol wipes. |
| Oversized Prototype Stencil Kit-Lead Free | Prototype SMT Stencil (exceeding 10” x 12”), lead free solder paste, pick & place tool, temperature marker (390° thru 450°), 1 pair of gloves, and 2 alcohol wipes. |
| Hand Stencil | Single component rework stencil, bent up on two sides for handling. |
| Metal Charge | Solder paste stencil thickness less that 0.004” and over 0.008”. |
| Frameless Stencil for use in a Universal Frame | Frameless stencil to fit an interchangeable plate system. Includes SMT, PRO 2, QTS, SPR. |
| Surface Finishes | Tin/Lead, Silver, Gold fingers, ENIG, OSP, Hard Gold, Soft Gold. |
| 29 x 29 Low Profile Framed Solder Stencil | Low Profile (1/2” thick frame) 29 x 29 framed stencil. |
| 8 x 10 Framed Stencil | Cast Aluminum 8 x 10 framed solder stencil - maximum squeegee area 5”x7”. |
| 12 x 12 Framed Stencil | Cast Aluminum 12 x 12 framed solder stencil- maximum squeegee area 9”x9”. |
| 12 x 17 Framed Stencil | Cast Aluminum 12 x 17 framed solder stencil - maximum squeegee area 9”x14”. |
| 15 x 15 Framed Stencil | Cast Aluminum 15 x 15 framed solder stencil - maximum squeegee area 12”x12”. |
| 20 x 20 Framed Stencil | Cast or Extruded 20 x 20 framed solder stencil - maximum squeegee area 17”x17”. |
| 29x29 Framed Stencil | Extruded Aluminum 29 x 29 framed solder stencil - maximum squeegee area 22”x22”. |
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Framed SMT Stencils | |
Frameless SMT Stencils | |
Prototype SMT Stencils | |
Prototype SMT Stencil with Kit (Leaded or Lead Free) | |
Hand or Rework Stencils | |
Stencils replace hand soldering of surface mount devices, and the inconsistencies created by hand soldering. They allow for direct placement of solder paste to the surface to be soldered.
The stencil thickness is determined by the smallest component land pattern. If you are not sure, our design staff can choose the optimum thickness based on the data you supply.
Home base apertures are used to control solder balling and tomb-stoning of chip components such as 0603’s and 0805’s. The shape is generated by taking a percentage of the length of the pad, and percentage of the width of the pad to create a partial triangle where the points face toward the center of the component body. The resulting shape resembles a baseball "Home base" which is where its name is derived. The most commonly utilized percentage for length and width is 50%.
Trapezoidal Apertures are created by distorting the beam on the laser, creating a draft in the aperture wall. Trapezoidal Apertures are effective if you plan on a long dwell time between printing of solder paste and placement of components. The taper in the aperture wall causes the paste to sit on top of itself, rather than sliding out the sides. The shape of the trapezoid can be seen in cross section of the stencil opening.
Fiducials are alignment marks consisting of a 1mm circle surrounded by a 2mm clearance. If your screen printer is equipped with a vision system, fiducials half cut (into the thickness) of the stencil will allow for the printer to automatically align the board with the stencil. If you are manually aligning the stencil with the board, you could either fully cut the fiducials through the stencil or just use any surface mount pad to align the stencil.
Yes, the coating will treat both the surface of the stencil, as well as the aperture walls.
Fiducials are alignment marks consisting of a 1mm circle surrounded by a 2mm clearance. If your screen printer is equipped with a vision system, fiducials half cut (into the thickness) of the stencil will allow for the printer to automatically align the board with the stencil. If you are manually aligning the stencil with the board, you could either fully cut the fiducials through the stencil or just use any surface mount pad to align the stencil.
