LMX9820ASM datasheet(39/44 Pages) NSC

39 / 44 page

Revision 1.0

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15.0 Soldering (Continued)

15.0 Soldering

The LMX9820A bumps are designed to melt as part of the

Surface Mount Assembly (SMA) process. The LMX9820A

is assembled with a high-temperature solder alloy to

ensure there are no re-reflow conditions imposed upon the

module when reflowed to a PCB with these typical low tem-

perature 60/40 (S = 183°C, L = 188°C), 62/36/2 (E =

179°C), or 63/37 (E = 183°C) solder alloys.

Where:

• S: Solidus

– Denotes the points in a phase diagram representing

the temperature at which the solder composition be-

gins to melt during heating, or complete freezing dur-

ing cooling.

• L: Liquidus

– Denotes the points in a phase diagram representing

the temperature at which the solder has molten com-

ponents. The temperature that melting starts at.

• E: Eutectic

– Denotes solid to liquid without a plastic phase.

The low-temperature solder alloy will reflow with the solder

bump and provide the maximum allowable solder-joint reli-

ability.

Reflow at a peak of 215 --> 220°C (approximately 30 sec-

onds at peak). Do not to exceed 220°C, measured in close

proximity of the modules. to avoid any potential re-reflow

conditions.

Table 41 and Figure 27 on page 40 provide the soldering

details required to properly solder the LMX9820A to stan-

dard PCBs. The illustration serves only as a guide and

National is not liable if a selected profile does not work.

Table 41. Soldering Details

Parameter

Value

PCB Land Pad Diameter

24 mil

PCB Solder Mask Opening

30 mil

PCB Finish (HASL details)

63/37 (difference in thickness < 28 micron)

Stencil Aperture

28 mil

Stencil Thickness

5 mil

Solder Paste Used

Low temperature 60/40 (S = 183°C, L = 188°C),

62/36/2 (E = 179°C),

or 63/37 (E = 183°C) solder alloys1

Flux Cleaning Process

No Clean Flux System1

Reflow Profiles

See Figure 27 on page 40

Typically defined by customer.

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