EMIF03-SIM02M8

Recommendation on PCB assembly

7/10

5

Recommendation on PCB assembly

5.1

Stencil opening design

1.

General recommendation on stencil opening design

a)

Stencil opening dimensions: L (Length), W (Width), T (Thickness).

Figure 16.

Stencil opening dimensions

b)

General Design Rule

Stencil thickness (T) = 75 ~ 125 µm

2.

Reference design

a)

Stencil opening thickness: 100 µm

b)

Stencil opening for central exposed pad: Opening to footprint ratio is 50%.

Example: Stencil opening L = 680 µm, W = 300 µm

Footprint (see Figure 13) L = 1000 µm, W = 400 µm

c)

Stencil opening for leads: Opening to footprint ratio is 90%.

Example: Stencil opening L = 570 µm, W = 190 µm

Footprint (see Figure 13) L = 600 µm, W = 200 µm

5.2

Solder paste

1.

Halide-free flux qualification ROL0 according to ANSI/J-STD-004.

2.

“No clean” solder paste is recommended.

3.

Offers a high tack force to resist component movement during high speed

4.

Solder paste with fine particles: powder particle size is 20-45 µm.

L

T

W

Aspect Ratio

W

T

-----

1.5

≥

=

Aspect Area

LW

×

2T L

W

+

()

----------------------------

0.66

≥

=