# US 10,770,312 B2 · Under-fill deflash for a dual-sided ball grid array package

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- Number: US 10,770,312 B2
- Document ID: US10770312B2
- Status: Granted
- Kind: B2
- Application number: 16/566,844
- Filed: 2019-09-10
- Published: 2020-03-05
- Granted: 2020-09-08
- Earliest claimed: 2017-01-31
- Assignees: Skyworks Solutions, Inc.
- Applicants: Skyworks Solutions, Inc.
- Inventors: Robert Francis Darveaux
- Web page: https://patentgrep.com/patent/US10770312B2

## CPC

- H10W 74/012: {of encapsulations on active surfaces of flip-chip devices, e.g. forming underfills}
- H10P 34/42: with electromagnetic radiation, e.g. laser annealing (laser cutting H10P54/20)
- H10P 54/00: Cutting or separating of wafers, substrates or parts of devices
- H10P 72/7402: {Wafer tapes, e.g. grinding or dicing support tapes}
- H10W 42/20: protecting against electromagnetic or particle radiation, e.g. light, X-rays, gamma-rays or electrons
- H10W 46/00: Marks applied to devices, e.g. for alignment or identification
- H10W 70/097: {Cleaning}
- H10W 70/099: {Connecting interconnections to insulating or insulated package substrates, interposers or redistribution layers}
- H10W 70/611: {for connecting multiple chips together}
- H10W 70/65: Shapes or dispositions of interconnections
- H10W 70/685: comprising multiple insulating layers
- H10W 70/687: {characterized by the outer layers being for protection, e.g. solder masks, or for protection against chemical or mechanical damage}
- H10W 72/0198: {batch processes}
- H10W 74/014: {using batch processing}
- H10W 74/019: {using temporary auxiliary substrates (H10W74/017 takes precedence)}
- H10W 74/121: {by multiple encapsulations, e.g. by a thin protective coating and a thick encapsulation}
- H10W 74/15: on active surfaces of flip-chip devices, e.g. underfills
- H10W 74/47: comprising organic materials, e.g. plastics or resins
- H10W 90/00: Package configurations
- H10W 99/00: Subject matter not provided for in other groups of this subclass
- H10P 76/2041: {Photolithographic processes}
- H10W 46/607: {Located on parts of packages, e.g. on encapsulations or on package substrates}
- H10W 72/01371: {Cleaning, e.g. oxide removal or de-smearing}
- H10W 72/072: {of bump connectors}
- H10W 72/073: {of die-attach connectors}
- H10W 72/07302: {using an auxiliary member}
- H10W 72/07304: {the auxiliary member being temporary, e.g. a sacrificial coating}
- H10W 72/07331: {Connecting techniques}
- H10W 72/07336: {Soldering or alloying}
- H10W 72/07338: {hardening the adhesive by curing, e.g. thermosetting}
- H10W 72/075: {of bond wires}
- H10W 72/252: {comprising solid metals or solid metalloids, e.g. PbSn, Ag or Cu}
- H10W 72/325: {Die-attach connectors having a filler embedded in a matrix}
- H10W 72/352: {comprising metals or metalloids, e.g. solders}
- H10W 72/353: {not comprising solid metals or solid metalloids, e.g. ceramics}
- H10W 72/354: {comprising polymers}
- H10W 72/387: {Flow barriers}
- H10W 72/5445: {being orthogonal to a side surface of the chip, e.g. parallel arrangements}
- H10W 72/884: {Die-attach connectors and bond wires}
- H10W 74/10: characterised by their shape or disposition
- H10W 74/117: {the substrate having spherical bumps for external connection}
- H10W 90/22: the stacked chips being on both top and bottom sides of a package substrate, interposer or RDL
- H10W 90/291: {characterised by containers, encapsulations, or other housings for the stacked chips}
- H10W 90/701: {characterised by the relative positions of pads or connectors relative to package parts}
- H10W 90/724: {between a chip and a stacked insulating package substrate, interposer or RDL}
- H10W 90/734: {between a chip and a stacked insulating package substrate, interposer or RDL}
- H10W 90/735: {between a chip and a laterally-adjacent insulating package substrate, interposer or RDL}
- H10W 90/754: {between a chip and a stacked insulating package substrate, interposer or RDL}
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

Described herein methods of manufacturing dual-sided packaged electronic modules that control the distribution of an under-fill material between one or more components and a packaging substrate. The disclosed technologies include under-filling one or more components and deflashing a portion of the under-fill to remove under-fill material prior to attaching solder balls. The deflashing step removes a thin layer of under-fill material that may have coated contact pads for the ball grid array. Because the solder balls are not present during under-fill, there is little capillary action drawing material away from the components being under-filled. This can reduce the frequency of voids under the components being under-filled. Accordingly, the disclosed technologies control under-fill for dual-sided ball grid array packages using under-fill deflash prior to attaching solder balls of the ball grid array.

## Claims

### Claim 1

A method of fabricating a packaged radio-frequency device, the method comprising:
mounting components to a first side of a packaging substrate;
mounting a lower component to a second side of the packaging substrate, the second side of the packaging substrate including a plurality of contact pads for mounting solder balls;
under-filling the lower component mounted on the second side of the packaging substrate with an under-filling agent, the under-filling agent coating a portion of at least one of the plurality of contact pads;
deflashing a portion of the under-filling agent; and
mounting the solder balls on the contact pads of the second side of the packaging substrate after the portion of the under-filling agent has been deflashed.

### Claim 2 (depends on 1)

The method of claim 1 wherein deflashing includes removing a thin layer of the under-filling agent.

### Claim 3 (depends on 1)

The method of claim 1 wherein deflashing includes removing the portion of the under-filling agent that coats the portion of the at least one of the plurality of contact pads.

### Claim 4 (depends on 1)

The method of claim 1 wherein a size of a keep out zone is reduced by deflashing a portion of the under-filling agent prior to mounting the solder balls.

### Claim 5 (depends on 1)

The method of claim 1 wherein the components mounted to the first side comprise electrical components.

### Claim 6 (depends on 1)

The method of claim 1 wherein the lower component comprises an electrical component.

### Claim 7 (depends on 1)

The method of claim 1 wherein under-filling the lower component prior to mounting the solder balls results in a lack of capillary action drawing the under-fill material toward the contact pads of the solder balls thereby reducing the occurrence of under-fill voids under the lower component.

### Claim 8

A method for manufacturing packaged radio-frequency devices, the method comprising:
mounting one or more lower components on an underside of a packaging substrate so that there is a gap between the one or more lower components and the packaging substrate, the packaging substrate having an upper side with one or more upper components mounted thereto, the underside of the packaging substrate having a die area and a contact pad area having a plurality of contact pads for through-mold connections;
after mounting the one or more lower components, depositing an under-fill material on the packaging substrate so that the under-fill material penetrates into the gap, the under-fill material coating a portion of the contact pad area;
after depositing the under-fill material, deflashing a portion of the under-fill material that covers one or more targeted areas; and
mounting through-mold connections to the underside of the packaging substrate after deflashing the portion of the under-fill material.

### Claim 9 (depends on 8)

The method of claim 8 wherein the through-mold connections include solder balls.

### Claim 10 (depends on 8)

The method of claim 8 further comprising singulating individual units from the packaging substrate to yield a plurality of dual-sided packages.

### Claim 11 (depends on 8)

The method of claim 8 wherein the under-fill material includes a sealing resin or an epoxy.

### Claim 12 (depends on 8)

The method of claim 8 further comprising curing the under-fill material.

### Claim 13 (depends on 8)

The method of claim 8 wherein deflashing includes removing a thin layer of the under-fill material.

### Claim 14 (depends on 8)

The method of claim 8 wherein deflashing includes removing the portion of the under-fill material that coats the portion of the contact pad area.

### Claim 15 (depends on 8)

The method of claim 8 wherein the one or more upper components comprises one or more electrical components.

### Claim 16 (depends on 8)

The method of claim 8 wherein the one or more lower components comprises one or more electrical components.

### Claim 17

A method for manufacturing packaged radio-frequency devices, the method comprising:
mounting one or more lower components on an underside of a packaging substrate so that there is a gap between the one or more lower components and the packaging substrate, the packaging substrate having an upper side with one or more upper components mounted thereto, the underside of the packaging substrate having a die area and a contact pad area having a plurality of contact pads for through-mold connections;
after mounting the one or more lower components, depositing an under-fill material on the packaging substrate so that the under-fill material penetrates into the gap, the under-fill material coating a portion of the contact pad area;
after depositing the under-fill material, deflashing a portion of the under-fill material that covers one or more targeted areas such that a size of a keep out zone is reduced by deflashing the portion of the under-fill material prior to mounting any through-mold connections to the underside of the packaging substrate.

### Claim 18 (depends on 17)

The method of claim 17 wherein deflashing includes removing the portion of the under-fill material that coats the portion of the contact pad area.

### Claim 19 (depends on 17)

The method of claim 17 further comprising mounting through-mold connections to the underside of the packaging substrate after deflashing the portion of the under-fill material.