# US 12,183,688 B2 · Integrated circuit die package stiffeners of metal alloys having exceptionally high CTE

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 12,183,688 B2
- Document ID: US12183688B2
- Status: Granted
- Kind: B2
- Application number: 17/192,770
- Filed: 2021-03-04
- Published: 2022-09-08
- Granted: 2024-12-31
- Earliest claimed: 2021-03-04
- Assignees: Intel Corporation
- Applicants: Intel Corporation
- Inventors: Valery Ouvarov-Bancalero; John Harper; Malavarayan Sankarasubramanian; Patrick Nardi; Bamidele Daniel Falola; Ravi Siddappa; James Mertens
- Web page: https://patentgrep.com/patent/US12183688B2

## CPC

- H10W 42/121: {protecting against mechanical damage (H10W76/00, H10W74/00 take precedence)}
- H05K 7/1461: {Slidable card holders; Card stiffeners; Control or display means therefor}
- H10W 76/17: characterised by their materials
- H10W 76/40: Fillings or auxiliary members in containers, e.g. centering rings (fillings or auxiliary members for thermal protection or control in containers or encapsulations H10W40/70)
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS

## Abstract

A stiffener for an integrated circuit (IC) package assembly including an IC die electrically interconnected to a substrate. The stiffener is to be mechanically attached to the substrate adjacent to at least one edge of the IC die and have a coefficient of linear thermal expansion (CTE) exceeding that of the substrate. The stiffener may be an “anti-invar” metallic alloy. Anti-invar alloys display “anti-invar” behavior where thermal expansion of the material is significantly enhanced relative to other compositions of the particular alloy system. A package stiffener may be a high-Mn steel, for example, such as ASTM International A128. In other examples, a package stiffener is a MnCuNi, FeNiMn, or FeNiCr alloy having an average CTE over a range of 25-100° C. of at least 18 ppm, and a room temperature modulus of elasticity of at least 120 GPa.

## Claims

### Claim 1

An integrated circuit (IC) device assembly, comprising:
a package substrate;
an IC die including a first side electrically interconnected to a first side of the package substrate; and
a stiffener physically coupled to the package substrate and adjacent to an edge of the IC die, wherein the stiffener comprises an alloy of metals with a constituent concentration for which the alloy displays the anti-invar effect, has a mean CTE, over a range of 25°-100° C., greater than 18 ppm/K, and a room temperature modulus of elasticity exceeding 130 GPa.

### Claim 2 (depends on 1)

The IC device assembly of claim 1, wherein the mean CTE is greater than that of the package substrate.

### Claim 3 (depends on 2)

The IC device assembly of claim 2, wherein the mean CTE is at least 19 ppm/K.

### Claim 4 (depends on 3)

The IC device assembly of claim 3, wherein the room temperature modulus of elasticity is at least 180 GPa.

### Claim 5 (depends on 3)

The IC device assembly of claim 3, wherein the mean CTE is at least 20 ppm/K.

### Claim 6 (depends on 1)

The IC device assembly of claim 1, wherein the alloy comprises two or more of Fe, Mn, Ni, Pt, Cr, Co, or Cu.

### Claim 7 (depends on 6)

The IC device assembly of claim 6, wherein the alloy has a composition for which a ratio of valence electrons/atoms is less than 8.5.

### Claim 8 (depends on 6)

The IC device assembly of claim 6, wherein the alloy comprises three or more of Fe, Mn, Ni, Pt, Cr, Co, or Cu.

### Claim 9 (depends on 6)

The IC device assembly of claim 6, wherein the alloy comprises primarily Fe and at least one of Mn, Ni, Pt, Cr, or Co.

### Claim 10 (depends on 9)

The IC device assembly of claim 9, wherein the alloy comprises primarily Fe and two of Ni, Cr, or Mn.

### Claim 11 (depends on 10)

The IC device assembly of claim 10, wherein the alloy is FexNiyMnz, and wherein x is within 2 wt % of 74 wt %, y is within 2 wt % of 20 wt %, and z is within 2 wt % of 6 wt %.

### Claim 12 (depends on 11)

The IC device assembly of claim 11, wherein the alloy is FexNiyCrz, and wherein x is within 2 wt % of 75 wt %, y is within 2 wt % of 25 wt %, and z is within 2 wt % of 3 wt %.

### Claim 13 (depends on 8)

The IC device assembly of claim 8, wherein the alloy comprises primarily Mn and at least one of Cu or Ni.

### Claim 14 (depends on 13)

The IC device assembly of claim 13, wherein the alloy is MnxCuyNiz, and wherein x is within 2 wt % of 72 wt %, y is within 2 wt % of 18 wt %, and z is within 2 wt % of 10 wt %.

### Claim 15 (depends on 1)

The IC device assembly of claim 1, wherein the stiffener further comprises a surface finish over the alloy, the surface finish comprising at least one of Ni or Au.

### Claim 16

A computing system, comprising:
a package substrate;
an IC die including a first side electrically interconnected to a first side of the package substrate;
a stiffener physically coupled to the package substrate and adjacent to an edge of the IC die, wherein the stiffener comprises an alloy of metals with at least 72 wt % Fe and at least 18 wt % Ni, or at least 70 wt % Mn and at least 16 wt % Cu;
a system-level thermal solution coupled to a second side of the IC die; and
a host board coupled to a second side of the package substrate by plurality of second electrical interconnects.

### Claim 17

An integrated circuit (IC) die package stiffener, the stiffener comprising:
a contiguous frame with a bottom surface to attach to a package substrate, the frame to enclose one or more IC die within an interior of the frame, wherein the frame is of a substantially homogenous metal alloy comprising two or more of Fe, Mn, Ni, Pt, Cr, Co, or Cu and having a composition for which a ratio of valence electrons/atoms is less than 8.5.

### Claim 18 (depends on 17)

The IC die package stiffener of claim 17, wherein the metal alloy is FexNiyMnz, and wherein x is within 2 wt % of 74 wt %, y is within 2 wt % of 20 wt %, and z is within 2 wt % of 6 wt %.

### Claim 19 (depends on 17)

The IC die package stiffener of claim 17, wherein the metal alloy is FexNiyCrz, and wherein x is within 2 wt % of 75 wt %, y is within 2 wt % of 25 wt %, and z is within 2 wt % of 3 wt %.

### Claim 20 (depends on 17)

The IC die package stiffener of claim 17, wherein the metal alloy is MnxCuyNiz, and wherein x is within 2 wt % of 72 wt %, y is within 2 wt % of 18 wt %, and z is within 2 wt % of 10 wt %.

### Claim 21 (depends on 17)

The IC die package stiffener of claim 17, wherein the frame is substantially rectangular, the interior has an area of 1000-3000 mm2, and the frame has a thickness of 50 μm-3 mm from the bottom surface to a top surface of the frame.