Beam Lead PIN Diodes for
Phased Arrays and Switches
Technical Data
HPND-4028
HPND-4038
Features
• Low Capacitance
0.025 pF Maximum at 1 MHz
Guaranteed Min./Max.
• Fast Switching
2.0 nsec
• Low Resistance at Low Bias
1.5
Ω
at I
F
= 10 mA (Typical)
• Rugged Construction
Typical 10 Gram Lead Pull
• Silicon Nitride Passivation
690 (27)
650 (26)
330 (13)
260 (10)
220 (9)
180 (7)
180 (7)
160 (6)
110 (4.5)
90 (3.5)
280 (11)
240 (9)
Description
The HPND-4028 and 4038 beam
lead PIN diodes are designed for
low capacitance, low resistance,
and fast switching at microwave
frequencies. These characteristics
are achieved at low bias levels for
minimal power consumption.
Advanced processing techniques
ensure uniform and consistent
electrical performance, allowing
guaranteed capacitance windows.
This translates to improved
performance in phased array
applications.
Rugged construction and strong
beams ensure high assembly
yields while nitride passivation
and polyimide coating ensure
reliability.
12 (0.47)
8 (0.32)
60 (2.4)
40 (1.6)
DIMENSIONS IN
µM
(1/1000 INCH)
Outline 83
Maximum Ratings
Operating Temperature ....................................................... -65°C to +150°C
Storage Temperature ........................................................... -65°C to +200°C
Power Dissipation at T
CASE
= 25°C ................................................. 250 mW
(Derate linearly to zero at 150
°
C.)
Minimum Lead Strength ................................... 4 grams pull on either lead
per MIL-S-19500, LTPD = 20
Applications
These beam lead PIN diodes are
designed for use in stripline,
coplanar waveguide, or micro-
strip circuits. Applications
include phase shifting and
switching. The guaranteed
capacitance windows ensure
uniform performance in phased
array radar. The low capacitance
makes them ideal for circuits
requiring high isolation in the
series configuration. These
devices have been fully charac-
terized and S-parameters have
been provided.
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Bonding and Handling
Procedures for Beam
Lead Diodes
1. Storage
Under normal circumstances,
storage of beam lead diodes in
Agilent supplied waffle/gel packs
is sufficient. In particularly dusty
or chemically hazardous environ-
ments, storage in an inert atmo-
sphere desiccator is advised.
2. Handling
In order to avoid damage to beam
lead devices, particular care must
be exercised during inspection,
testing, and assembly. Although
the beam lead diode is designed to
have exceptional lead strength, its
small size and delicate nature
requires that special handling
techniques be observed so that
the devices will not be mechani-
cally or electrically damaged. A
vacuum pickup is recommended
for picking up beam lead devices,
particularly larger ones, e.g.,
quads. Care must be exercised to
assure that the vacuum opening of
the needle is sufficiently small to
avoid passage of the device
through the opening. A #27 tip is
recommended for picking up
single beam lead devices. A 20X
magnification is needed for
precise positioning of the tip on
the device. Where a vacuum
pickup is not used, a sharpened
wooden Q-tip dipped in isopropyl
alcohol is very commonly used to
handle beam lead devices.
3. Cleaning
For organic contamination use a
warm rinse of trichloroethane, or
its locally approved equivalent,
followed by a cold rinse in ac-
etone and methanol. Dry under
infrared heat lamp for 5–10
minutes on clean filter paper.
Freon degreaser, or its locally
approved equivalent, may replace
trichloroethane for light organic
contamination.
• Ultrasonic cleaning is not
recommended.
• Acid solvents should not be
used.
4. Bonding
Thermocompression:
See
Application Note 979 “The Han-
dling and Bonding of Beam Lead
Devices Made Easy”. This method
is good for hard substrates only.
Wobble:
This method picks up
the device, places it on the
substrate and forms a thermo-
compression bond all in one
operation. This is described in the
latest version of MIL-STD-883,
Method 2017, and is intended for
hard substrates only.
Resistance Welding or
Parallel-GAP Welding:
To make
welding on soft substrates easier,
a low pressure welding head is
recommended. Suitable equip-
ment is available from HUGHES,
Industrial Products Division in
Carlsbad, CA.
Epoxy:
With solvent free, low
resistivity epoxies (available from
ABLESTIK and improvements in
dispensing equipment, the quality
of epoxy bonds is sufficient for
many applications.
5. Lead Stress
In the process of bonding a beam
lead diode, a certain amount of
“bugging” occurs. The term
bugging
refers to the chip lifting
away from the substrate during
the bonding process due to the
deformation of the beam by the
bonding tool. This effect is
beneficial as it provides stress
relief for the diode during thermal
cycling of the substrate. The
coefficient of expansion of some
substrate materials, specifically
soft substrates, is such that some
bugging is essential if the circuit is
to be operated over wide tempera-
ture extremes.
Thick metal clad ground planes
restrict the thermal expansion of
the dielectric substrates in the X-Y
axis. The expansion of the dielec-
tric will then be mainly in the Z
axis, which does not affect the
beam lead device. An alternate
solution to the problem of dielec-
tric ground plane expansion is to
heat the substrate to the maxi-
mum required operating tempera-
ture during the beam lead attach-
ment. Thus, the substrate is at
maximum expansion when the
device is bonded. Subsequent
cooling of the substrate will cause
bugging, similar to bugging in
thermocompression bonding or
epoxy bonding. Other methods of
bugging are preforming the leads
during assembly or prestressing
the substrate.
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