Self-opening vent hole in an overmolded semiconductor device

• US 5,612,576 A
• Filed: 10/13/1992
• Issued: 03/18/1997
• Est. Priority Date: 10/13/1992
• Status: Expired due to Term

• Current Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Martin, Fonzell D. J., Wilson, Howard P.
• Primary Examiner(s): WHITEHEAD JR, CARL W
• Application Number:
  US07/960,337
• Time in Patent Office: 1,617 Days
• Field of Search: 257/666, 257/667, 257/678, 257/680, 257/683, 257/699, 257/701, 257/702, 257/787, 257/788, 257/790, 257/793, 257/796, 257/798, 257/676, 257/693, 257/684, 337/247, 337/297, 337/232, 337/166, 337/290, 337/273
• US Class Current: 257/788
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/32057 in side view
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2224/83385 Shape, e.g. interlocking features
• CPC Class Codes: H01L 2224/85399 Material
• CPC Class Codes: H01L 23/13 characterised by the shape
• CPC Class Codes: H01L 23/3128 the substrate having spherical bumps for external connection
• CPC Class Codes: H01L 23/49816 Spherical bumps on the substrate for external connection, e.g. ball grid arrays [BGA]
• CPC Class Codes: H01L 23/49827 Via connections through the substrates, e.g. pins going through the substrate, coaxial cables H01L23/49822, H01L23/49833, H01L23/4985, H01L23/49861 take precedence
• CPC Class Codes: H01L 24/32 of an individual layer connector
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/73 Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01005 : Boron [B]
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/01087 : Francium [Fr]
• CPC Class Codes: H01L 2924/12042 : LASER
• CPC Class Codes: H01L 2924/15151 : the die mounting substrate comprising an aperture, e.g. for underfilling, outgassing, window type wire connections
• CPC Class Codes: H01L 2924/15311 : being a ball array, e.g. BGA
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/207 : Diameter ranges
• CPC Class Codes: H01L 2924/3512 : Cracking

Abstract

A self-opening vent hole semiconductor device (10) can be manufactured to reduce the risk of popcorning during solder reflow. The device contains a semiconductor die (22) mounted on a die mounting area (15) of a substrate (12). A venting hole (16) is approximately centrally located in the die mounting area. A venting hole sealing cap (20) covers and seals the venting hole. A layer of patterned solder resist (18) adheres to a lower surface of the substrate. The venting hole sealing cap can be made from the layer of solder resist, and can be configured to be either physically isolated from the solder resist layer or physically partially connected to the solder resist layer. The venting hole sealing cap is designed to be a weakest interface within the device so that it self-opens upon an internal pressure less than a destructive pressure to the device. Solder balls (30) provide external electrical connections for the device.

Claims

1. A self-opening vent hole semiconductor device comprising:

a substrate having first and second surfaces, a die mounting;

area, and a vent hole approximately centrally located in the die mounting area, the substrate being composed of an electrically insulative material and carrying a pattern of conductive traces on at least one surface of the substrate;

a vent hole sealing cap overlying the second surface of the substrate to cover and seal the vent hole in the substrate with a first adhesive force;

a semiconductor die mounted on the first surface of the substrate on the die mounting area with an adhesive having a second adhesive force between the semiconductor die and the die mounting area of the substrate, the semiconductor die being electrically connected to the pattern of conductive traces;

a package body formed by an encapsulating material covering the semiconductor die on the first surface of the substrate, wherein the package body and the vent hole sealing cap are composed of different materials and wherein the vent hole sealing cap is physically isolated from the package body, the encapsulating material having a third adhesive force to the substrate; and

a plurality of external electrical connections to the semiconductor die, wherein the plurality of external electrical connections are electrically connected to the pattern of conductive traces;

wherein said second and third adhesive forces are stronger than said first adhesive force, thus making the vent hole sealing cap a weakest interface in the self-opening vent hole semiconductor device such that the vent hole sealing cap automatically breaks away from the vent hole at a vapor pressure that is less than a destructive pressure to the semiconductor device.

2. The semiconductor device of claim 1 wherein the vent hole sealing cap is composed of a solder resist material.

3. The semiconductor device of claim 2 wherein the vent hole sealing cap is physically partially connected by a tab of solder resist material to a layer of patterned solder resist adhering to the second surface of the substrate.

4. The semiconductor device of claim 1 wherein the vent hole further comprises an annular metal land on the second surface of the substrate surrounding a plated through-hole in the substrate.

11. The semiconductor device of claim 1 wherein the substrate comprises a material selected from a group consisting of:

bismaleimide-triazine resin, an epoxy-glass, and a flexible film.

12. The semiconductor device of claim 1 wherein the adhesive comprises a material selected from a group consisting of:

a silver-filled epoxy paste, a B-stage epoxy, a silver-filled polyimide, and a cyanoacrylate.

5. A self-opening vent hole semiconductor device comprising:

a substrate having first and second surfaces, a thickness, a die mounting area, and a vent hole approximately centrally located in the die mounting area, wherein the vent hole extends through the thickness of the substrate, the vent hole comprising an annular metal land on the second surface of the substrate surrounding a plated through-hole in the substrate, the substrate being composed of an electrically insulative material and carrying a pattern of conductive traces on at least one surface of the substrate;

a vent hole sealing cap covering and sealing the vent hole in the substrate wherein the vent adheres to a portion of the annular metal land with a first adhesive force;

a semiconductor die mounted on the first surface of the substrate on the die mounting area with an adhesive having a second adhesive force between the semiconductor die and the die mounting area of the substrate, the semiconductor die being electrically connected to the pattern of conductive traces;

a package body formed by an encapsulating material covering the semiconductor die on the first surface of the substrate, wherein the package body and the vent hole sealing cap are composed of different materials and wherein the vent hole sealing cap is physically isolated from the package body, the encapsulating material having a third adhesive force to the substrate; and

a plurality of solder balls electrically connected to the pattern of conductive traces to provide external electrical connections to the semiconductor die;

wherein said second and third adhesive forces are stronger than said first adhesive force, thus making the vent hole sealing cap a weakest interface in the self-opening vent hole semiconductor device such that the vent hole sealing cap automatically breaks away from the vent hole at a vapor pressure that is less than a destructive pressure to the semiconductor device.

6. The semiconductor device of claim 5 wherein the vent hole sealing cap is composed of a solder resist material.

7. The semiconductor device of claim 6 wherein the vent hole sealing cap is physically partially connected by tab of solder resist material to a layer of patterned solder resist adhering to the second surface of the substrate.

8. The semiconductor device of claim 5 wherein the substrate comprises a material selected from a group consisting of:

a bismaleimide-triazine resin, an epoxy-glass, and a flexible film.

9. The semiconductor device of claim 5 wherein the semiconductor die is electrically connected the pattern of conductive traces by a plurality of wire bonds.

10. The semiconductor device of claim 5 wherein the adhesive comprises a material selected from a group consisting of:

a silver-filled epoxy paste, a B-stage epoxy, a silver-filled polyimide, and a cyanoacrylate.