AN-0004125 Datasheet, PDF (1/9 Pages) M/A-COM Technology Solutions, Inc. – Mounting Methods for High Power RF Plastic Devices

AN-0004125
Mounting Methods for High Power RF Plastic Devices
Rev. V1
Introduction
The purpose of this application note is to provide
customers with a guide for mounting plastic-
packaged high power RF devices to a circuit board.
Adherence to the methods described in this
document will enable the product to achieve good
RF performance and reliable operation throughout
its life.
Background
High power plastic-overmolded packages have a
unique construction, see Figure 1. In the high power
package the die is attached to a heat slug
embedded in the plastic but exposed on the bottom
side. The die is connected internally to leads that
protrude from the package body on a different plane
than the exposed portion of the heat slug.
Using this guide customers should be able to
develop mounting procedures that are compatible
with their product design and manufacturing
processes. These processes will produce a part with
good thermal grounding for heat dissipation, good
electrical grounding for stable RF performance, and
reliable lead connections.
Figure 1 – Cross-section diagram of high power
plastic-overmolded part
This design enables the package to be mounted in a
customer’s board so that the package heat slug can
be in direct contact with a metal carrier while the
leads can be in contact with the printed circuit board
(PCB). This package construction and the high
power nature of the device lead to some challenges
that need to be considered. These challenges
include:
 Maintaining good contact between exposed heat
slug and carrier for thermal transfer and
electrical grounding.
 Attention to cavity height, stack-up of material
and process tolerances.
 Attaching leads to PCB without overstressing.
There are several ways to mount high power plastic
packages and each has its advantages and
disadvantages. It is important to understand these
so that the customer can make the best decision
considering cost, performance, manufacturability,
and reliability.
1
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