Functional Characteristics
Atlas
®
Digital Amplifier Complete Technical Reference
21
2
Whether using tape, pads, paste, or epoxy, as shown in
, the thermal transfer material that is used as the
interface should not extend to the area under the Atlas’ tabs because this may reduce the amount of compression that
occurs in the thermal transfer area. The following table provides dimensions for the applied thermal transfer material
for the two available Atlas package sizes:
Figure 2-6:
Recommended
Atlas Unit
Thermal
Transfer
Material
Dimensions
2.3.3
Atlas Installation
There are a number of precautions and procedures that should be followed to maintain the electrical and mechanical
integrity of the Atlas unit during installation.
Soldering Atlas units in place
. Applications that utilize Atlas units that are not mechanically mated to a heat sink or that
are mated to a self-standing heat sink may utilize a standard soldering process without special precautions or
procedures. Applications that involve Atlas units mated to a supporting plate and that will be soldered to the PCB
should take special care to insure that the solder joints are not stressed by the supporting plate once installed. The
recommended method to achieve this is to mechanically mate the Atlas to the supporting plate before soldering the
Atlas into the PCB. If, for whatever reason, this is not possible, then special care should be taken to insure that the
Atlas is precisely aligned with the supporting plate after soldering and before mechanical attachment so that upon
mechanical attachment no stress is placed on the Atlas unit, the solder contacts, or the PCB.
Mounting surface flat and clean
. Thermal performance as well as safe operation of the Atlas requires that the surface that
the Atlas is mounted to be flat and clean, free of dust, grease, or foreign objects. The recommended maximum
deviation of the mating surface flatness is 3 mils (.076 mm).
Mechanical mounting limits
. Applications that will utilize a mechanical attachment to the Atlas via the Atlas’s mounting
tabs should take special care not to overstress the mechanical tabs. Regardless of the attachment method, which is most
commonly screws but may also be clips or inserts, the linear force applied to each mechanical tab should not exceed
certain values as shown in the following table and the accompanying
Atlas Package Size
Maximum Pad
Dimensions
Ultra Compact
.1.00" x .95" (25.4 mm x 24.1mm)
Compact
1.40" x 1.50" (35.6 mm x 38.1
mm)
Atlas Package Size
Maximum Direct Force
Per Tab
Screw Type, Corresponding
Maximum Rotary Torque
Ultra Compact
25 pounds (111 N)
M2.0 x .40, 11.0oz-in (.078 N-m)
Compact
35 pounds (156 N)
M2.5 x.45, 12.5oz-in (.088 N-m)
1.40”
(35.6)
1.50”
(38.1)
1.00”
(25.4)
.95”
(24.1)