CR-15 Package Handling and Mounting Procedure

Rev. V5

Application Note

M567

1

ADVANCED: Data Sheets contain information regarding a product M/A-COM Technology Solutions

is considering for development. Performance is based on target specifications, simulated results,

and/or prototype measurements. Commitment to develop is not guaranteed.

PRELIMINARY: Data Sheets contain information regarding a product M/A-COM Technology

Solutions has under development. Performance is based on engineering tests. Specifications are

typical. Mechanical outline has been fixed. Engineering samples and/or test data may be available.

Commitment to produce in volume is not guaranteed.

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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.

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.

CERAMIC

BASE PLATE

4X .06 X 45°

CHAMFER

6

5

4

3

2

1

7

8

9

10

.010 SQ.

ORIENTATION TAB

2X o .096 THRU

o.004 M A B C

.090 MAX

.33

.005 ± .002

.030

.318 ± .010

.328 ± .010

.050 MIN.

10X

.530

.70

.159

.010 ± .003

10X

.040

.100

4X

.115 ± .010

.050

4X

.085

- C -

- B -

- A -

CR-15 Package Outline