M567 Datasheet, PDF (1/2 Pages) M/A-COM Technology Solutions, Inc. – CR-15 Package Handling and Mounting Procedure

Application Note
M567
CR-15 Package Handling and Mounting Procedure
Rev. V5
Introduction
The CR-15 is a high frequency, low thermal resistance
package, which should be given special attention during
cavity design and package mounting, to insure proper
electrical and thermal performance. The package
consists of a co-fired ceramic construction with a copper-
tungsten base and iron-nickel-cobalt leads. The finish
consists of electrolytic gold over nickel plate.
After component installation, the package is hermetically
sealed using a ceramic lid and an 80/20 gold/tin eutectic
solder. This bolt down style package provides a robust
interface between a highly integrated GaAs MMIC device
and a circuit board which may be assembled using
conventional surface mount techniques.
The CR-15 has successfully completed a rigorous in-
house package qualification program, which exceeds the
requirements of industry guidelines for package element
evaluation.
CR-15 Package Outline
10X .050 MIN.
-C-
.085
.70
.530
10 9 8
76
-B-
.328 ± .010
.318 ± .010
.010 SQ.
ORIENTATION TAB
12
.115 ± .010
4X .050
-A-
.030
.005 ± .002
.159
3
45
10X .010 ± .003
2X o .096 THRU
o.004 M A B C
4X .06 X 45°
CHAM FER
4X .100
.33
CERAMIC
.090 MAX
.040
BASE PLATE
Mounting Cavity Design
For a PC board thickness of 0.010 inches or greater, the
mounting cavity dimensions should be 0.324 x 0.708
inches with a tolerance of ± 0.002 inches. The PC board
cutout dimensions should be 0.336 x 0.708 inches with a
tolerance of ± 0.002 inches regardless of board thickness.
Consistent device location with respect to the circuit
board is important in order to achieve repeatable
performance. This can be accomplished by integration
techniques which minimize variations in device location
within the cavity.
Peeling stresses exerted on the package lead to ceramic
joint of the package, should be avoided. Damage to the
package lead attach area is typically caused by mounting
the device into an excessively deep cavity. The cavity
depth should be designed so that the package leads are
nominally 0.004” above the circuit board. This
relationship of the lead to circuit board height will be
affected by several factors, including the circuit board and
metalization thicknesses, the circuit board attachment
method, and the thickness of any shim material used
under the package.
Mounting Surface Concerns
Surface discontinuities or flatness steps in the mounting
surface should be avoided. Typical causes for these
deformities are variations in machining depth, inadequate
casting finish or foreign particles on the surface. It is
highly recommended that the CR-15 cavity floor be milled
to a flatness of 0.0005 inches maximum, and a surface
finish of 32 micro-inches maximum, using a single tool
path. Any abrupt changes in the cavity floor flatness may
cause catastrophic or latent damage to the device,
voiding the manufacturer’s warranty.
A thin shim made of a ductile material may be used prior
to installation of the CR-15, if desired, to improve the
thermal performance of the package to housing interface.
The shim material should be selected so as to preclude
any dissimilar metal interaction. A gold plated copper
shim of 0.001 inch thickness is recommended for outdoor
environments, while a 0.001 inch thickness is aluminum
shim is a lower cost option suitable for more protected
environments. The shim should be dimensioned to match
those of the CR-15 base to insure that the shim rests in
the cavity floor without binding. A shim that has been
manufactured or installed improperly may prevent the CR-
15 package from fully seating into the cavity floor.
The use of thermally conductive grease is not
recommended.
1
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changes to the product(s) or information contained herein without notice.