Laser stencils can be divided into two subcategories: laser solder paste stencils and laser red glue stencils.

Solder paste stencil
For SMT laser stencils, most people will consider solder paste stencils. Because the current mainstream is to apply solder paste, which can better ensure that the components are better adhered to the pads of the PCB board during reflow soldering. The phenomenon of false welding and false welding is relatively rare. It is suitable for PCB boards with many chip components, or some high-density PCB boards with dense pin IC or BGA on the board. However, the cost of solder paste is also relatively high. Good solder paste will affect the tin condition on the PCB to a certain extent.
A brief summary of the general solder paste stencil opening methods is as follows:
CHIP component
A. The package is a 0201 component, and the inner distance is guaranteed to be no less than 0.23mm and no greater than 0.28mm.
B. The package is a 0402 component, and the inner distance must not be less than 0.35 or greater than 0.45mm (when the inner distance is less than 0.35mm, it needs to be moved outward to 0.35mm; when the inner distance is greater than 0.45mm, it needs to be expanded to 0.45mm). If the inner distance is too large, Can be adjusted appropriately to 0.5mm
C. The package is for 0603 component openings (when the inner distance is less than 0.55mm, it needs to be moved outward to 0.6mm, when it is larger than 0.80MM, it needs to be expanded to 0.80mm)
D. The package is 0805, 1206 and above components, generally not limited, but the 0805 inner distance should be kept at least 0.7 or above
E.0805 and above components (except diodes) must be treated to prevent solder beads, as shown below
If the width of 0805 components is less than 1.0MM and the width of 1206 is less than 1.3MM, do not prevent tin beads (unless required by customers)
Or if the document does not have a silk screen layer, and the component direction and polarity cannot be distinguished, there is no need to prevent solder beads. If the customer requires protection, ask customer service personnel to ask for a silk screen layer. The customer’s note states that solder beads must be prevented, starting from 0805 components. Defend

2. In order to ensure the welding quality, SOT23 opens holes according to the pad 1:1.

3.SOT89
Bridge, bridge width is 0.8-1.0MM

4. High-power transistors such as SOT252 and SOT223 are built with a bridge in the middle, a “cross” or “well” shape, or divided into multiple small blocks. The width of the bridge depends on the situation (pad size)
5. Special-shaped components
   (1) For this type of SD card holder, add 0.2MM to the outer three sides, and extend the pins to 0.15MM.

(2). Requirements for this type of headphone holder: pin extension 0.15MM

(3) Requirements for this type of SIM card holder: add 0.15 to the three outer sides of the fixed feet, and extend the pins to 0.15MM

(4) Requirements for this type of switch: 0.1MM extension on the three outer sides

(5) USB requirements: add 0.15 on the three outer sides of the fixed foot, and extend the pin by 0.1MM

(6) Requirements for this type of module: long extension 0.15MM, and a safe distance in the width direction

(7) Requirements for this type of toggle switch: the upper two fixed legs have a long extension of 0.15MM, plus 0.1MM on each side in the width direction, and the bottom two pins have a long extension of 0.15MM, plus 0.1MM on each side in the width direction.

(8) Requirements for this type of parts: For the upper part, add 0.15MM to the outer three sides of the fixed foot, and 0.15mm to the pin extension. For the lower part, add 0.1MM to each side of the width, and 0.15MM to the long extension.

The above requirements depend on the situation. If you can, increase it. If you can’t, you don’t need to add it (for example, the distance from the surrounding components is too small, and the pad is already at the edge of the board)
6.IC type (W means width, L means length)
(1) PITCH=0.8-1.27mm, the width is generally between 45%-60% of PITCH. The width depends on the line layer pad. The smaller the pad on the line layer, the smaller the value, and the larger the line. Take a larger value
(2) PITCH=0.635-0.65mm, W=0.3-0.33MM, L 1:1 and rounded at both ends.
(3) PITCH=0.5mm, W=0.24mm, if L is less than 1.5MM, extend it by 0.1MM and round both ends.
(4) PITCH=0.4mm, W=0.19mm, L is extended by 0.1MM and both ends are rounded.
(5) PITCH=0.3mm, W=0.16MM, L extends outward by 0.1MM, and both ends are rounded (if the length is <0.8mm, extend outward by 0.15mm).

Above (0.65-1.27), if L<1mm, the length needs to be extended outward by 0.1mm

7.BGA type
PITCH＝0.4mm, open 0.23m
PITCH＝0.45mm, open 0.26mm
PITCH＝0.5mm, open 0.3mm
PITCH＝0.65mm, open 0.35mm
PITCH＝0.8mm, open 0.45mm
PITCH＝1.0mm, open 0.55mm
PITCH＝1.27mm, open 0.65mm
If the aperture on the line is too far from this data, please contact customer service
0.4 0.5IC ground pad, open a square hole according to 60-70% of the pad. If the square hole is larger than 1.5, please build a bridge with a minimum width of 0.3MM. Make it a cross, a field or a tic, depending on the size of the pad. It depends. If the ground pad is already very small, such as about 1.0MM, there is no need to reduce it.
If there are dense pin ICs or BGAs on the board and the board density is high, you can consider electropolishing <

Send us an inquiry , we will get back to you soon ,thank you!