US7187075B1
Expired / Lapsed
US
⏱️ 0.0 years remaining
Stress relieving film for semiconductor packages
Assignee: National Semiconductor Corp
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Filing: 2004-07-29
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Granted: 2007-03-06
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Expires: 2024-07-29
Abstract
Abstract Techniques for reducing the mechanical stress imposed upon semiconductor dice by protective molding compounds during times of temperature fluctuation. A thermoplastic material is attached to a top surface of a die to relieve the stress. The thermoplastic material serves as a cushion between the die and the molding compound when the components expand and contract. The thermoplastic material can be shaped such that it does not cover bond pads on the surface of a die.
Inventors
- 👤 Tan Eng Hwa
- 👤 Lim Peng Soon
- 👤 Santhiran S/O Nadarajah
- 👤 Ong Sze Yan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 06:30
CPC Classifications
H; H10; H10P; H10P95/00; H10P95/90; H10W; H10W76/00; H10W76/40; H10W72/00; H10W72/851; H10W72/874; H10W72/884; H10W74/00; H10W74/10; H10W74/111; H10W90/00; H10W90/701; H10W90/751; H10W90/756
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
150 words
A semiconductor device comprising: a semiconductor die having a top surface; a molding compound that encapsulates the semiconductor die; and a piece of thermoplastic material positioned on the top surface of the semiconductor die such that the piece of thermoplastic material is positioned between the top surface of the semiconductor die and the molding compound, the thermoplastic material being suitable for absorbing stress imposed by thermal expansion and contraction of the die and the molding compound, wherein the piece of thermoplastic material has a transition temperature in a range of temperatures experienced by the semiconductor device during operation of the semiconductor device, whereby when heat generated by the die during operation of the die heats the thermoplastic material to at least the transition temperature of the thermoplastic material, the thermoplastic material will soften to cushion the die from stress caused by thermal incompatibility between the die and the molding compound.
Claim 2
Dependent Claim
150 words
A semiconductor device comprising: a semiconductor die having a top surface; a molding compound that encapsulates the semiconductor die; and a piece of thermoplastic material positioned on the top surface of the semiconductor die such that the piece of thermoplastic material is positioned between the top surface of the semiconductor die and the molding compound, the thermoplastic material being suitable for absorbing stress imposed by thermal expansion and contraction of the die and the molding compound, wherein the piece of thermoplastic material has a transition temperature in a range of temperatures experienced by the semiconductor device during operation of the semiconductor device, whereby when heat generated by the die during operation of the die heats the thermoplastic material to at least the transition temperature of the thermoplastic material, the thermoplastic material will soften to cushion the die from stress caused by thermal incompatibility between the die and the molding compound.
Claim 3
Dependent Claim
21 words
A semiconductor device as recited in claim 1 wherein the piece of thermoplastic material is in the form of a sheet.
Claim 4
Dependent Claim
17 words
A semiconductor device as recited in claim 1 wherein the thermoplastic material softens when its temperature rises.
Claim 5
Dependent Claim
48 words
A semiconductor device as recited in claim 1 wherein the top surface of the semiconductor die has a plurality of bond pads and wherein the piece of thermoplastic material has an outline shape such that the piece of thermoplastic material does not cover any of the bond pads.
Claim 6
Dependent Claim
37 words
A semiconductor device as recited in claim 1 wherein the top surface of the semiconductor die contains a plurality of integrated circuits and wherein the piece of thermoplastic material covers at least the plurality of integrated circuits.
Claim 7
Dependent Claim
39 words
A semiconductor device as recited in claim 1 wherein the semiconductor die and the molding compound have different coefficients of thermal expansion such that the semiconductor die and the molding compound expand and contract with temperature at different rates.
Claim 8
Dependent Claim
41 words
A semiconductor device as recited in claim 1 further comprising: a supplementary stress absorbing structure attached on top of the piece of thermoplastic material that also absorbs stress imposed by thermal expansion and contraction of the die and the molding compound.
Claim 9
Dependent Claim
18 words
A semiconductor device as recited in claim 7 wherein the supplementary stress absorbing structure is formed of silicon.
Claim 10
Dependent Claim
33 words
A semiconductor device as recited in claim 7 wherein the supplementary stress absorbing structure has a modulus of elasticity that is higher than a modulus of elasticity for the piece of thermoplastic material.
Claim 11
Dependent Claim
36 words
A semiconductor device as recited in claim 1 wherein the semiconductor die has a bottom surface, the semiconductor device further comprising: a die attach pad that is attached to the bottom surface of the semiconductor die.
Claim 12
Dependent Claim
26 words
A semiconductor device as recited in claim 10 wherein the die attach pad is attached to the semiconductor die via a second layer of thermoplastic material.
Claim 13
Dependent Claim
26 words
A semiconductor device as recited in claim 1 wherein there are two separate pieces of thermoplastic material positioned on the top surface of the semiconductor die.
Claim 14
Dependent Claim
46 words
A semiconductor device as recited in claim 1 wherein a modulus of elasticity of the piece of thermoplastic material is less than a modulus of elasticity of the molding compound when the thermoplastic material is heated to at least the transition temperature of the thermoplastic material.
Claim 15
Dependent Claim
25 words
A semiconductor device as recited in claim 1 wherein the thickness of the thermoplastic material is in the range of approximately 0.5 to 3 mils.
Claim 16
Dependent Claim
151 words
A semiconductor device comprising: a semiconductor die having a top surface; a molding compound that encapsulates the semiconductor die; and a stress absorbing sheet positioned on the top surface of the semiconductor die such that the stress absorbing sheet is positioned between the top surface of the semiconductor die and the molding compound, the stress absorbing sheet being suitable for absorbing stress imposed by thermal expansion and contraction of the die and the molding compound, wherein the stress absorbing sheet has a transition temperature in a range of temperatures experienced by the semiconductor device during operation of the semiconductor device, whereby when heat generated by the die during operation of the die heats the stress absorbing sheet to at least the transition temperature of the stress absorbing sheet, the stress absorbing sheet will soften to cushion the die from stress caused by thermal incompatibility between the die and the molding compound.
Claim 17
Dependent Claim
151 words
A semiconductor device comprising: a semiconductor die having a top surface; a molding compound that encapsulates the semiconductor die; and a stress absorbing sheet positioned on the top surface of the semiconductor die such that the stress absorbing sheet is positioned between the top surface of the semiconductor die and the molding compound, the stress absorbing sheet being suitable for absorbing stress imposed by thermal expansion and contraction of the die and the molding compound, wherein the stress absorbing sheet has a transition temperature in a range of temperatures experienced by the semiconductor device during operation of the semiconductor device, whereby when heat generated by the die during operation of the die heats the stress absorbing sheet to at least the transition temperature of the stress absorbing sheet, the stress absorbing sheet will soften to cushion the die from stress caused by thermal incompatibility between the die and the molding compound.
Claim 18
Dependent Claim
46 words
A semiconductor device as recited in claim 15 wherein the top surface of the semiconductor die has a plurality of bond pads and wherein the stress absorbing sheet has an outline shape such that the stress absorbing sheet does not cover any of the bond pads.
Claim 19
Dependent Claim
36 words
A semiconductor device as recited in claim 16 wherein the top surface of the semiconductor die contains a plurality of integrated circuits and wherein the stress absorbing sheet covers at least the plurality of integrated circuits.
Claim 20
Dependent Claim
18 words
A semiconductor device as recited in claim 15 wherein the stress absorbing sheet softens when its temperature rises.
Claim 21
Dependent Claim
25 words
A semiconductor device as recited in claim 15 wherein there are two separate stress absorbing sheets positioned on the top surface of the semiconductor die.
Claim 22
Dependent Claim
47 words
A semiconductor device as recited in claim 15 wherein a modulus of elasticity of the stress absorbing sheet is less than a modulus of elasticity of the molding compound when the stress absorbing sheet is heated to at least the transition temperature of the stress absorbing sheet.
Claim 23
Dependent Claim
26 words
A semiconductor device as recited in claim 15 wherein the thickness of the stress absorbing sheet is in the range of approximately 0.5 to 3 mils.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2010-03-05 | 2010-09-04 | 2011-03-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2014-03-05 | 2014-09-04 | 2015-03-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2018-03-05 | 2018-09-04 | 2019-03-06 | $7700.00 | Window Closed / Lapsed |