Assembly Information
The MiniPak diode is mounted to
the PCB or microstrip board using
the pad pattern shown in
Figure 21.
0.4
0.5
0.4
0.3
0.5
0.3
Figure 21. PCB Pad Layout, MiniPak
(dimensions in mm).
SMT Assembly
Reliable assembly of surface
mount components is a complex
process that involves many
material, process, and equipment
factors, including: method of
heating (e.g., IR or vapor phase
reflow, wave soldering, etc.)
circuit board material, conductor
thickness and pattern, type of
solder alloy, and the thermal
conductivity and thermal mass of
components. Components with a
low mass, such as the MiniPak
package, will reach solder reflow
temperatures faster than those
with a greater mass.
Agilent’s diodes have been quali-
fied to the time-temperature
profile shown in Figure 23. This
profile is representative of an IR
reflow type of surface mount
assembly process.
After ramping up from room
temperature, the circuit board
with components attached to it
(held in place with solder paste)
350
300
250
221
200
150
100
50
0
0
30
60
90
120
150
passes through one or more
preheat zones. The preheat zones
increase the temperature of the
board and components to prevent
thermal shock and begin evaporat-
ing solvents from the solder paste.
The reflow zone briefly elevates
the temperature sufficiently to
produce a reflow of the solder.
The rates of change of tempera-
ture for the ramp-up and cool-
down zones are chosen to be low
enough to not cause deformation
of the board or damage to compo-
nents due to thermal shock. The
maximum temperature in the
reflow zone (T
MAX
) should not
exceed 255°C.
These parameters are typical for a
surface mount assembly process
for Agilent diodes. As a general
guideline, the circuit board and
components should be exposed
only to the minimum temperatures
and times necessary to achieve a
uniform reflow of solder.
This mounting pad pattern is
satisfactory for most applications.
However, there are applications
where a high degree of isolation is
required between one diode and
the other is required. For such
applications, the mounting pad
pattern of Figure 22 is
recommended.
0.40 mm via hole
(4 places)
0.20
0.8
2.40
Peak Temperature
Min. 240°C
Max. 255°C
TEMPERATURE (°C)
0.40
2.60
Reflow Time
Min. 60 s
Max. 90 s
Preheat 130– 170°C
Min. 60 s
Max. 150 s
Figure 22. PCB Pad Layout, High Isolation
MiniPak (dimensions in mm).
This pattern uses four via holes,
connecting the crossed ground
strip pattern to the ground plane
of the board.
180
210
240
270
300
330
360
TIME (seconds)
Figure 23. Surface Mount Assembly Temperature Profile.
8
AGILENT [ AGILENT TECHNOLOGIES, LTD. ]
