# US 9,040,352 B2 · Film-assist molded gel-fill cavity package with overflow reservoir

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- Number: US 9,040,352 B2
- Document ID: US9040352B2
- Status: Granted
- Kind: B2
- Application number: 13/535,438
- Filed: 2012-06-28
- Published: 2014-01-02
- Granted: 2015-05-26
- Earliest claimed: 2012-06-28
- Assignees: Freescale Semiconductor, Inc.
- Applicants: Shun Meen Kuo; Li Li
- Inventors: Shun Meen Kuo; Li Li
- Web page: https://patentgrep.com/patent/US9040352B2

## CPC

- H10W 76/47: Solid or gel fillings
- B60C 3/00: Tyres characterised by the transverse section
- B60C 23/04: mounted on the wheel or tyre
- H10W 74/111: {the semiconductor body being completely enclosed}
- H10W 74/124: {the encapsulations having cavities other than that occupied by chips}
- H10W 90/811: {Multiple chips on leadframes}
- H10W 72/075: {of bond wires}
- H10W 72/884: {Die-attach connectors and bond wires}
- H10W 72/952: {comprising metals or metalloids, e.g. PbSn, Ag or Cu}
- H10W 74/00: Encapsulations, e.g. protective coatings
- H10W 74/10: characterised by their shape or disposition
- H10W 90/732: {between stacked chips}
- H10W 90/752: {between stacked chips}
- H10W 90/753: {between laterally-adjacent chips}
- H10W 90/756: {between a chip and a stacked lead frame, conducting package substrate or heat sink}
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- B60C: VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES

## Abstract

A semiconductor device package having a cavity formed using film-assisted molding techniques is provided. Through the use of such techniques the cavity can be formed in specific locations in the molded package, such as on top of a device die mounted on the package substrate or a lead frame. In order to overcome cavity wall angular limitations introduced by conformability issues associated with film-assisted molding, a gel reservoir feature is formed so that gel used to protect components in the cavity does not come in contact with a lid covering the cavity or the junction between the lid and the package attachment region. The gel reservoir is used in conjunction with a formed level setting feature that controls the height of gel in the cavity. Benefits include decreased volume of the cavity, thereby decreasing an amount of gel-fill needed and thus reducing production cost of the package.

## Claims

### Claim 1

A method comprising:
providing a second semiconductor device embodied within a packaged semiconductor device assembly, wherein the second semiconductor device comprises a first and second major surface;
forming an encapsulated region over the second major surface of the second semiconductor device using an encapsulant;
forming a cavity region in the encapsulant over a first portion of the second major surface of the second semiconductor device using a film-assisted molding technique, wherein
a mold used for the film-assisted molding technique defines a gel stop feature along a wall of the cavity region,
the gel stop feature comprises a gel level set feature and a gel overflow reservoir feature, wherein the gel stop feature is configured to permit silicone gel rising to a level above the gel level set feature to flow over the gel level set feature into the gel overflow reservoir feature;
the first portion of the second major surface of the second semiconductor device is exposed in the cavity region; and
affixing a first semiconductor device on at least a portion of the first portion of the second major surface of the second semiconductor device, wherein the first semiconductor device is located entirely within the cavity region.

### Claim 2 (depends on 1)

The method of claim 1 further comprising: providing a lead frame comprising a plurality of leads and a flag portion of the lead frame;
affixing the second semiconductor device to the flag portion of the lead frame, wherein
the first major surface is affixed to the flag portion of the lead frame and electrically coupling the second semiconductor device to one or more of the plurality of leads, wherein said forming the encapsulated region comprises encapsulating the lead frame, electrical contacts of the second semiconductor device coupled to the lead frame, and a portion of the second semiconductor device excluding the first portion of the surface.

### Claim 3 (depends on 2)

The method of claim 2 wherein the second semiconductor device is a control die, the first semiconductor device is a pressure sensor, and the control die is configured to process signals from the pressure sensor.

### Claim 4 (depends on 1)

The method of claim 1 further comprising: placing a silicone gel in the cavity region and over and surrounding the first semiconductor device, and placing a pressure permeable cap over the cavity region on a lid attach shoulder formed in the cavity by the mold, wherein a bottom portion of the lid attach shoulder is above a maximum silicone gel depth permitted by the gel stop feature, and the pressure permeable cap is not in contact with the silicone gel.

### Claim 5 (depends on 4)

The method of claim 4 further comprising: curing the silicone gel subsequent to said placing the silicone gel in the cavity region.