SMT Stencil - Key to PCB Assembly and High Quality Electronic Production

Overview of SMT Stencil

The SMT (surface mounted technology) stencil is one of the main products PCBONLINE provides, and is a key tool for PCB assembly. With it, the solder paste can simply and precisely print onto the circuit board, and your factory can easily achieve massive automatic production.
PCBONLINE offers high/medium/low volume of PCB assembly and EMS service, but if you want to assemble by your own, we also provide a good solution - using SMT stencils of best quality to quickly assemble PCB by yourself.

Advantages of SMT Stencil

Why Choose SMT Stencils from PCBONLINE

• PCBONLINE adopts the laser cutting method characterized by high precision and easy to demodulate by trapezoidal opening.
• Our production is of little influence of objective factors, and accurate cutting is ensured.
• The stencil is conducive to the release of solder paste because of the naturally trapezoidal aperture design (the upper hole is 1mil-5mil larger than the lower).
• Accurate data - hole size error is about 0.3~0.5mil, and the positioning accuracy is less than 0.12mil.
• Our SMT stencils are durable and very thin. We provide stencils 0.1mm, 0.12mm, 0.15mm, and 0.2mm's thick.
• We fully consider the mold release of solder paste, width/thickness and area ratio, tin connection, tin, etc., on SMT stencil design.
• You can online order framed or frameless SMT stencils from us and get an instant quote.

SMT Stencil - Manufacturing and Tech Specs

Process of SMT

SMT (surface mounted technology) is a series of processes to assemble components onto the bare circuit boards. The multiple phases are: stencil design according to the board > solder paste printing > component placement > reflow soldering > AOI optical inspection > maintenance (if needs) > sub-board.
An SMT stencil enables you to print the solder paste onto the board precisely and quickly by machine, and while the solder paste is still in liquid state, place desirable parts onto the solder joints also by machine. Then you get the PCBA and reflow to coagulate the solder paste so that the components are soldered tightly. Then is the AOI optical inspection, an automated visual inspection of printed circuit board to test for catastrophic failure and quality defects. If anything wrong is detected, you fix it. Finally, you cut or separate the boards ready for the final product assembly.
PCBONLINE has rich experience in the whole SMT process including but not limited to SMT stencil design and manufacturing. If you order PCB from us but want to assemble the boards by your own, it is suggested that you apply SMT assembly and buy SMT stencils from us. SMT enables fast, precise, and cost-effective assembling, and PCBONLINE, the PCB manufacturer, knows how to design and manufacture your stencils to be best, and we also provide suggestion in PCB assembly for free.

SMT Stencil Types

There are four types of SMT stencils. The most widely used types are the framed and framless SMT stencils, which are the main stencils produced by PCBONLINE. But still, you can get other types of SMT stencils from us.

1.Framed SMT Stencils

Framed PCB stencil is a laser cutting stencil process mounted permanently in the stencil frame with the help of mesh border to stretch the stencil foil tightly in the frame. Framed stencils come into design consideration for high volume screen printing.

Smooth aperture walls of framed SMT stencil are usable for less and equal to 16 Mil fine pitch as well as Micro BGS's. The permanent circuit board mounting offers maximum integrity levels and gives non-fading fiducial results.
2.Frameless SMT Stencils

Frameless PCB stencil, on the other hand, works with the stencil tensioning systems called reusable stencil frames. It also comes in a laser cutting stencil process category. This SMT stencil design is not glued permanently in the frame. They cost very less as compare to framed stencil and saves money by well maintain superior performance and quality.

The storage space is saved due to compact size. High engineering quality promotes maximum performance throughout the frameless PCB stencil life.
3.Prototype SMT Stencil

These are customized stencils designed in the CAD or Gerber to match the prototype PCB. They are solder paste frameless stencils explicitly created for printing manually.

Prototype SMT stencils remove the tiresome error-prone process of soldering the prototype circuit boards with hands.

The maximum efficiency and quick alignment reduce the assembly time of the prototype. It is cost-effective, requires no machine use, and is an easy-to-understandable circuit board printing process.
4.Electroformed SMT Stencils

This PCB stencil is nickel-based, made of electroforming foil mounted permanently in the stencil frame by using the mesh border to stretch the foil taut tightly. They have the best paste releasing characteristics. They are used commonly for excellent pitch SMT applications, Wafer Bumping (12-6 mil pitch), Flip Chip, and µBGAs.

About Solder Paste

The suspension of smooth solid particles in a flux vehicle makes a solder paste. In the electronic industry, it is commonly used in SMT stencil to SMD onto the printed circuits boards. The particle composition can be customized to produce a stainless steel paste of desirable melting consistency. Adding other metals changes the composition of paste depending upon application requirements. Shape, size, flux type, and metal content of particles vary to produce varying viscous paste.
There are three types of solder paste applications: 1. chemical etching, 2. laser cutting, 3. electroformed. The oldest, less expensive, and most widely practiced solder paste stencil method is chemical etching. Laser cutting and especially electroformed are used when precision is crucial.