8

www.fairchildsemi.com

RMPA2458 Rev. E

Applications Information

CAUTION: THIS IS AN ESD SENSITIVE DEVICE.

Precautions to Avoid Permanent Device Damage:

• Cleanliness: Observe proper handling procedures to ensure

clean devices and PCBs. Devices should remain in their

original packaging until component placement to ensure no

contamination or damage to RF, DC and ground contact

areas.

• Device Cleaning: Standard board cleaning techniques should

not present device problems provided that the boards are

properly dried to remove solvents or water residues.

• Static Sensitivity: Follow ESD precautions to protect against

ESD damage:

–A properly grounded static-dissipative surface on which to

place devices.

– Static-dissipative floor or mat.

–A properly grounded conductive wrist strap for each person

to wear while handling devices.

• General Handling: Handle the package on the top with a

vacuum collet or along the edges with a sharp pair of bent

tweezers. Avoiding damaging the RF, DC, and ground

contacts on the package bottom. Do not apply excessive

pressure to the top of the lid.

• Device Storage: Devices are supplied in heat-sealed,

moisture-barrier bags. In this condition, devices are protected

and require no special storage conditions. Once the sealed

bag has been opened, devices should be stored in a dry

nitrogen environment.

Device Usage:

Fairchild recommends the following procedures prior to

assembly.

• Assemble the devices within one year of removal from the dry

pack.

• During the one year period, the devices must be stored in an

environment of less than 60% relative humidity and a

maximum temperature of 30°C

• If the one year period or the environmental conditions have

been exceeded, then the dry-bake procedure, at 125°C for 24

hours minimum, must be performed.

Solder Materials & Temperature Profile:

Reflow soldering is the preferred method of SMT attachment.

Hand soldering is not recommended.

Reflow Profile

• Ramp-up: During this stage the solvents are evaporated from

the solder paste. Care should be taken to prevent rapid

oxidation (or paste slump) and solder bursts caused by violent

solvent out-gassing. A maximum heating rate is 3°C/sec.

• Pre-heat/soak: The soak temperature stage serves two

purposes; the flux is activated and the board and devices

achieve a uniform temperature. The recommended soak

condition is: 60-180 seconds at 150-200°C.

• Reflow Zone: If the temperature is too high, then devices may

be damaged by mechanical stress due to thermal mismatch or

there may be problems due to excessive solder oxidation.

Excessive time at temperature can enhance the formation of

inter-metallic compounds at the lead/board interface and may

lead to early mechanical failure of the joint. Reflow must occur

prior to the flux being completely driven off. The duration of

peak reflow temperature should not exceed 20 seconds.

Soldering temperatures should be in the range 255–260°C,

with a maximum limit of 260°C.

• Cooling Zone: Steep thermal gradients may give rise to

excessive thermal shock. However, rapid cooling promotes a

finer grain structure and a more crack-resistant solder joint.

The illustration below indicates the recommended soldering

profile.

Solder Joint Characteristics:

Proper operation of this device depends on a reliable void-free

attachment of the heat sink to the PWB. The solder joint should

be 95% void-free and be a consistent thickness.

Rework Considerations:

Rework of a device attached to a board is limited to reflow of the

solder with a heat gun. The device should be subjected to no

more than 15°C above the solder melting temperature for no

more than 5 seconds. No more than 2 rework operations should

be performed.

Recommended Solder Reflow Profile

150

Ramp-Up R ate

3

°C/sec max

25

Time 25

°C/sec t o peak temp

6 mi nutes max

Ramp-Do wn Rate

6

°C/sec max

Preheat, 150 to 200

°C

60 - 180 sec

200

217

Time above

li quidus temp

60 - 150 sec

100

260

Peak tem p

260 +0/-5

°C

10 - 20 sec

Time (Sec)

Ramp-Up R ate

3

°C/sec max

50