Fingerprint sensor and packaging method thereof

• US 9,875,387 B2
• Filed: 07/15/2016
• Issued: 01/23/2018
• Est. Priority Date: 05/16/2016
• Status: Active Grant

• Current Assignee: Egis Technology Inc.
• Original Assignee: Egis Technology Inc.
• Inventors: Chen, Pin-Yu
• Primary Examiner(s): Pizarro, Marcos D
• Assistant Examiner(s): TANG, SUIAN
• Application Number:
  US15/212,116
• Publication Number:
  US 20170330017A1
• Time in Patent Office: 557 Days
• Field of Search: 257414
• CPC Class Codes: G06V 40/1329 Protecting the fingerprint sensor against damage caused by the finger
• CPC Class Codes: H01L 21/4853 Connection or disconnection of other leads to or from a metallisation, e.g. pins, wires, bumps
• CPC Class Codes: H01L 21/4857 Multilayer substrates multilayer metallisation on monolayer substrate H01L21/4846
• CPC Class Codes: H01L 21/486 Via connections through the substrate with or without pins
• CPC Class Codes: H01L 21/565 Moulds
• 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 23/3114 the device being a chip scale package, e.g. CSP
• CPC Class Codes: H01L 23/3121 a substrate forming part of the encapsulation
• CPC Class Codes: H01L 23/49811 Additional leads joined to the metallisation on the insulating substrate, e.g. pins, bumps, wires, flat leads H01L23/49827 takes precedence
• CPC Class Codes: H01L 23/49822 Multilayer substrates multilayer metallisation on monolayer substrate H01L23/498
• 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 23/49838 Geometry or layout
• CPC Class Codes: H01L 23/60 Protection against electrostatic charges or discharges, e.g. Faraday shields
• CPC Class Codes: H01L 24/00 Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
• CPC Class Codes: H01L 24/48 of an individual wire connector
• 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 2924/10161 with a rectangular active surface
• CPC Class Codes: H01L 2924/181 : Encapsulation

Abstract

A fingerprint sensor is provided. The fingerprint sensor includes a multi-layer printed circuit board (PCB), a fingerprint sensing die and a molding compound. The multi-layer PCB includes a bottom dielectric layer, at least one intermediate dielectric layer disposed on the bottom dielectric layer, a top dielectric layer disposed on the intermediate dielectric layer and a trench. The trench is formed by digging out a portion of the intermediate dielectric layer and a portion of the top dielectric layer. The fingerprint sensing die is disposed in the trench of the multi-layer PCB and mounted on an upper surface of the bottom dielectric layer of the multi-layer PCB. The fingerprint sensing die includes a sensing array capable of sensing fingerprint information of a user. The fingerprint sensing die is covered by the molding compound, and the trench of the multi-layer PCB is filled with the molding compound.

Claims

1. A fingerprint sensor, comprising:

a multi-layer printed circuit board (PCB), comprising;

a bottom dielectric layer;

at least one intermediate dielectric layer disposed on the bottom dielectric layer;

a top dielectric layer disposed on the intermediate dielectric layer; and

a trench, wherein the trench is formed by digging out a portion of the intermediate dielectric layer and a portion of the top dielectric layer;

a fingerprint sensing die disposed in the trench of the multi-layer PCB and mounted on an upper surface of the bottom dielectric layer of the multi-layer PCB, comprising;

a sensing array, for sensing fingerprint information of a user; and

a molding compound,

wherein the fingerprint sensing die is completely covered by the molding compound, and the trench of the multi-layer PCB is filled with the molding compound,

wherein the multi-layer PCB further comprises;

a first metal layer disposed on an upper surface of the bottom dielectric layer and electrically connected to the fingerprint sensing die;

a second metal layer disposed on a lower surface of the bottom dielectric layer; and

a plurality of vias disposed in the bottom dielectric layer,

wherein the first metal layer is electrically connected to the second metal layer through the vias, so as to transmit the fingerprint information of the user from the fingerprint sensing die to a function module.

2. The fingerprint sensor as claimed in claim 1, wherein an upper surface of the molding compound and an upper surface of the top dielectric layer are coplanar.

3. The fingerprint sensor as claimed in claim 1, wherein a lower surface of the molding compound and a lower surface of the intermediate dielectric layer are coplanar.

4. The fingerprint sensor as claimed in claim 2, wherein the top dielectric layer and the intermediate dielectric layer have the same area.

5. The fingerprint sensor as claimed in claim 4, wherein an area of the bottom dielectric layer is greater than an area of the top dielectric layer.

6. The fingerprint sensor as claimed in claim 1, wherein the multi-layer PCB further comprises:

a third metal layer disposed on an upper surface of the top dielectric layer;

a ground plane disposed on a lower surface of the bottom dielectric layer; and

a plurality of through holes disposed through the top dielectric layer, the intermediate dielectric layer, and the bottom dielectric layer,

wherein the third metal layer is electrically connected to the ground plane through the through holes.

7. The fingerprint sensor as claimed in claim 6, wherein when an ESD event occurs, ESD energy is discharged from the third metal layer to the ground plane through the through holes without passing through the fingerprint sensing die.

8. The fingerprint sensor as claimed in claim 1, wherein the molding compound has a high dielectric constant.

9. The fingerprint sensor as claimed in claim 1, wherein a thickness of the intermediate dielectric layer is greater than that of the top dielectric layer and the bottom dielectric layer.

10. The fingerprint sensor as claimed in claim 1, wherein the trench of the multi-layer PCB is completely filled with the molding compound.

11. The fingerprint sensor as claimed in claim 1, wherein the molding compound is surrounded by the multi-layer printed circuit board.