GESP TECH -TRUSTWORTHY ONE-STOP PCB SERVICES HIGH QUALITY SMT STENCILS
Introduction
Surface Mount Technology (SMT) stencils can also named PCB stencils. solder paste stencils or laser stencils. the primary purpose of SMT stencils is to simply transfer solder paste to a bare circuit board. A stainless steel foil cut with a laser to create an opening for each surface mount device on the circuit board. Once the PCB stencil is properly aligned with the top of the board. Apply the solder paste to the opening (in one pass with a metal spatula). After separating the stainless steel foil from the board. the solder paste remains, ready for the manufacture of surface mount devices (SMDs). This process ensures consistency and saves time compared to manual soldering procedures.
BENEFITS OF SMT STENCILS
- Because stencils are highly repeatable, they produce exact print results.
- It allows the paste to completely cover the PCB at once. decreasing the time and effort required to create PCBs.
- They ensure accuracy and consistency while eliminating defects and errors.
- The stencil holds the etchant and other chemicals in place. preventing them from splattering all over your board.
- When working with little boards, using a stencil is extremely beneficial. because you can simply hold the entire thing in your hand while etching it.
- Stencils can be easily cleaned using abrasives. and appropriate chemicals to remove any contaminants.
- Using the proper stencil will prevent the following issues. which are typical when applying solder paste by hand. Circuit-breaker failures are obstructions in the soldering process. side walls with burrs, aperture inconsistency, and pads that are not properly positioned.
TYPE OF SMT STENCIL
Framed SMT Stencils:
Framed SMT stencils are simple to use and will save you a lot of time while soldering SMT parts. These laser-cut stencils fixed to a frame . and are suitable for high-volume screen printing. They are doubly bonded to prevent excessive wear and provide outstanding print performance.
Frameless SMT Stencils:
A frameless PCB stencil is one that does not have a frame attached to it. It is constructed without rails, allowing for more flexible PCBA construction. For small orders or prototypes, frameless PCB stencils are widely employed.
Prototype SMT Stencils:
Using your Gerber or CAD files. these cost-effective and efficient stencils are custom-made for prototype PCBs. These stencils designed for manual printing . and enable for speedy printing directly on your desk.
Electroformed SMT Stencils:
Electroformed stencils have the best paste release properties . and are hence perfect for the most precise applications. These stencils, made from electroformed sheets or foils. are appropriate for applications with a high aperture count.
SMT STENCIL SPECIFICATION:
- The top and bottom of the opening is naturally trapezoidal. and the upper opening is usually 1~5mil larger than the lower opening. which is conducive to the release of solder paste.
- The error of opening size is about 0.3~0.5mil, and the positioning accuracy is less than 0.12mil.
- The price is more expensive than chemical etching and cheaper than electroforming.
- Hole wall is not as smooth as electroforming template.
- Usually the thickness of stencil is 0.12~0.3mm. 6. Usually recommended for printing with component pitch value of 20mil or less.
GESP SMT STENCIL MANUFACTURER
Over the years, GESP has become a reliable partner for all your PCB needs. Whether you want to make PCBs or put them together. you can count on our skilled engineers who know the best ways to do things in the industry. Our state-of-the-art equipment makes sure that the PCBs we send out are technologically advanced. You can count on us to use the right tools. like SMT stencils, to make sure accuracy and precision. and keep costly mistakes from happening.
We can meet your needs whether you want a small number of prototypes or a lot of products. You can choose to use our turnkey services if you want an easy time.Just let us know what you need, and we’ll be happy to help. Because we offer prices that are very low, your project will still be very competitive.
HOW TO IDENTIFY THE QUALITY SMT STENCIL
Opening Shape
There are many opening shapes of stencil. usually rectangular, square and round. among which rectangular opening has better demolding efficiency than square and round opening.
Opening Size
To control the quality such as welding balls or bridging during the welding process. the stencil opening size is usually slightly smaller than the pad size. especially for fine pitch devices, the opening width at 15-20% compared to the corresponding pad width.
Width to Thickness Ratio
In printing, to prevent stencil blocking is very important. when the design of the stencil opening, the window length is less than 5 times the width. that is L < 5W. consider the width-thickness ratio, other considerations area ratio. width-thickness ratio as W / H For leaded printing. to make the stencil has good leakage. we need the width-thickness ratio > 1.5. and in lead-free printing, due to the small proportion of lead-free solder paste, poor wetting. In the case of lead-free printing. due to the smaller specific gravity of lead-free solder paste, poor wettability. so the opening should be larger, width-thickness ratio > 1.7.
Area ratio
If the window length is greater than 5 times the width. i.e. L>5W, consider the area ratio, area ratio = window area / window wall area = L*W/[2(L+W)H]. For leaded printing, in order to make the stencil have good leakage. we require the area ratio > 0.66; while in lead-free printing. due to the small proportion of lead-free solder paste, poor wettability. so the opening should be larger, area ratio > 0.7.
Material and Process
Check whether the material of stencil is made of stainless steel. Check whether the hole wall is smooth and free of burrs. focusing on the processing quality of the narrow pitch IC pin opening.