Guideline for PCB Footprint for SMD Components

In this tutorial we are going to learn about Guideline for PCB Footprint for SMD Components

SMD PAD GEOMETRIES

Generally manufacturer part vendors and assembly vendors be contacted for design recommendations. Or part manufacturing DATA SHEET (Specification sheet) the nominal dimensions of components will be used to design pad geometries.

If it is possible, measure the physical component and design the pad to those dimensions. PCB Designing for a component with multiple vendors as package dimensions may not be the same. When we design a common pad for multiple parts providing the dimensions do not vary too greatly. Don’t try to design pads more than 0.010″[0.254mm] larger than the normal pad design for a given part. If part manufacturer given part foot-print layout [figure] always uses same as. Generally nominal pad design shall be recommendations from part or assembly vendors, or pads derived from this design document. Do not design pads smaller than nominal. Generally some time some parts are not compatible with the wave solder process and should not be designed for use on the solder side of assemblies as damage to the components may occur during soldering.

FOR SMD COMPONENT

PAD Stack for 2 PIN Capacitor & Resistor Components

1.  Top layer – As per attached image of SMD PAD LENGTH X WIDTH is  [Rectangle pad] 1.6

+inside space 0.2 +outside space (0.2~0.5) = 2.0~2.33.2

+both outside 0.1        = 3.4

2. Bottom layer – For SMD PAD there is not required any PAD at bottom layer

3- Plane (Ground/Power)  – For SMD PAD there is not required any PAD at Ground/Power layer

4- Solder mask top – As per above pad will recommended 2.3+0.1 X 3.4+0.1

5- Solder paste top – For this Pad will be solder paste 2.3×3.4 [same as top layer pad]

      Which are use for steel stencil

6- Drill (nc drill) not required

7- D rill drawing (drill chart) not required

PAD Stack For SOIC or QFP IC

1- Top layer – As per image of SOIC PAD at top layer have [Rectangle pad] [F]1.25 [given data sheet] +inside space 0.2  +outside space (0.2~0.5)m = 1.95[D]0.5 [given data sheet] +both outside 0.1  = 0.7

NOTE: if you have fine pitch (0.5mm) than both outside is not required (due to fine pitch

2- Bottom layer     – For this ground & Power layer not required                                     

3- Plane (Ground / Power) – For this ground & Power layer not required

4- Solder mask top   – As per above pad will recommended 1.95+0.1 X 0.7+0.1

5- Solder paste top – For this Pad will be solder paste 1.25×0.7 [same as top layer pad]

      Which is use for steel stencil?

6- Drill (NC drill) – For this pad drill (NC Drill) not required

7- Drill drawing (drill chart) – For this pad drill chart not required

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