
1 - 14
12 Elizabeth Drive, Chelmsford, MA 01824 Phone: 978-250-3343
Fax: 978-250-3373
Web Site: www.hittite.com
MICROWAVE CORPORATION
F
EBRUARY
2001
A
M
1
S
SMT DISTRIBUTED GaAs MMIC AMPLIFIER 20 - 32 GHz
V
01.0900
HMC261LM1
HMC261LM1 Recommended SMT Attachment Technique
Preparation & Handling of the LM1 Millimeterwave Package for Surface Mounting
The HMC LM1 package was designed to be compatible with
high volume surface mount PCB assembly processes. The
LM1 package requires a specific mounting pattern to allow
proper mechanical attachment and to optimize electrical
performance at millimeterwave frequencies. This PCB layout
pattern can be found on each LM1 product data sheet. It can
also be provided as an electronic drawing upon request from
Hittite Sales & Application Engineering.
Follow these precautions to avoid permanent damage:
Cleanliness:
Observe proper handling procedures to ensure
clean devices and PCBs. LM1 devices should remain in their
original packaging until component placement to ensure no
contamination or damage to RF, DC & ground contact areas.
Static Sensitivity:
Follow ESD precautions to protect against
ESD strikes ( see catalog page 8 - 2 ).
General Handling:
Handle the LM1 package on the top with a
vacuum collet or along the edges with a sharp pair of bent
tweezers. Avoiding damaging the RF, DC, & ground contacts on the package bottom. Do not apply excess pressure
to the top of the lid.
Solder Materials & Temperature Profile:
Follow the information contained in the application note. Hand soldering is
not recommended. Conductive epoxy attachment is not recommended.
Solder Paste
Solder paste should be selected based on the user
’
s experience and be compatible with the metallization systems
used. See the LM1 data sheet Outline drawing for pin & ground contact metallization schemes.
Solder Paste Application
Solder paste is generally applied to the PCB using either a stencil printer or dot placement. The volume of solder
paste will be dependent on PCB and component layout and should be controlled to ensure consistent mechanical
& electrical performance. Excess solder may create unwanted electrical parasitics at high frequencies.
Solder Reflow
The soldering process is usually accomplished in a reflow oven but may also use a vapor phase process. A solder
reflow profile is suggested above.
Prior to reflowing product, temperature profiles should be measured using the same mass as the actual assemblies.
The thermocouple should be moved to various positions on the board to account for edge and corner effects and
varying component masses. The final profile should be determined by mounting the thermocouple to the PCB at the
location of the device.
Follow solder paste and oven vendor
’
s recommendations when developing a solder reflow profile. A standard
profile will have a steady ramp up from room temperature to the pre-heat temperature to avoid damage due to
thermal shock. Allow enough time between reaching pre-heat temperature and reflow for the solvent in the paste to
evaporate and the flux to completely activate. Reflow must then occur prior to the flux being completely driven off.
The duration of peak reflow temperature should not exceed 15 seconds. Packages have been qualified to with-
stand a peak temperature of 235
°
C for 15 seconds. Verify that the profile will not expose device to temperatures in
excess of 235
°
C.
Cleaning
A water-based flux wash may be used.
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T
0
C
TIME (min)
Recommended solder reflow profile
for HMC LM1 SMT package