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Molded Interconnect Substrate (MIS)

A midrange packaging option that offers lower density than fan-outs.
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Description

Molded interconnect substrate (MIS) is a mid-range packaging technology built on a leadframe substrate. It supports single- or multi-die configurations, enabling low-profile, fine-pitch packages.

On the surface, MIS resembles a fan-out wafer-level package. The big difference is that MIS is limited in terms of I/Os and densities. So in reality, MIS competes in the midrange space against some well-entrenched package types.

This packaging approach first appeared around 2010. It is ideal for 150 to 200 I/Os in low profiles. But the technology is limited to around 25μm line and space, meaning it is geared for mainly mid-range applications. Line and space refers to the width and pitch of a metal trace in a package. In comparison, a standard-density fan-out package, which is aimed for high-end apps, is defined as a package with less than 500 I/Os and greater than 8μm line/space. High-density fan-out has more than 500 I/Os and less than 8μm line/space.

The MIS substrate is thin. As such, it could be prone to warpage and uniformity issues during a process. Yield and cost are other issues.

MIS starts with a specialized substrate material for select IC packages. The MIS substrate itself is developed and sold by various vendors. A packaging house then takes that substrate and assembles an IC package around it. Some refer to the MIS substrate as a leadframe.

MIS is different than traditional substrates, as the technology consists of a pre-molded structure with one or more layers. Each layer is pre-configured with copper plating or interconnects to provide electrical connections in the package. All told, MIS supports single- or multi-die configurations, enabling low-profile, fine-pitch packages. It can be used to develop souped-up leaded packages, flip-chip, modules and system-in-packages (SiPs).


Fig. 1: MIS lead frame is pre-molded. Source: Unisem


Fig. 2: IC package using MIS Source: Prismark, Qdos

 

MIS has been around since the mid-2000s but saw more use starting in 2018.


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