There are two principles for SMT patch stencil opening:

a, the aspect ratio is greater than 1.5;

b, the area ratio is greater than 0.66

1. Calculate the thickness of the steel sheet according to the width of the smallest part; for example, the minimum width is 0.18mm, and the thickness of the steel sheet cannot exceed 0.12mm

2. After the thickness of the steel sheet is determined, the size of the opening is calculated according to the area ratio; for example, the size of the opening when the thickness of the steel sheet is 0.1mm cannot be less than 0.25mm

0.25*0.25=0.0625 (0.25+0.25)*0.1*2=0.1 0.0625/0.1=0.625<0.66,

Common sense questions about thickness

1. Pad spacing, the smaller the spacing between the pads, the thinner the thickness of the steel sheet.

2. Pad area, the larger the average area of the pad, the thicker it is, but in most cases, the large-area pad will be processed into a grid.

3. The thickness of the red glue stencil steel sheet is thicker than that of the solder paste stencil steel sheet, because if the amount of glue is small, the parts will be dropped during wave soldering.

4. The thickness of the stencil should meet the premise of the smallest pitch QFP and BGA, taking into account the smallest CHIP components.

5. If there are two or more IC devices at the same time, it should be based on the premise that there is no BGA.

Hole thickness specifications for laser steel mesh:

A． When the PITCH is 0.4IC and 0.4 and 0.5BGA, use 0.1MM thickness

B． PITCH is 0.5 for IC and 0.65 for BGA, using a thickness of 0.12MM

C． PITCH is 0.65 (including 0.65) or more IC and 0.8 (including 0.8) or more BGA, using a thickness of 0.15MM

D.0402 component with 0.12MM thickness

The above is for the solder paste stencil, the thickness of the red plastic stencil is usually 0.18MM

If the customer has special requirements for the thickness in the remarks of the steel mesh order, please select the thickness according to the customer’s requirements

(The above PITCH refers to the center-to-center spacing between adjacent pads)

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