ELECTRONIC COMPONENT WITH WIRE BONDS IN LOW MODULUS FILL ENCAPSULANT

• US 20090079097A1
• Filed: 09/25/2008
• Published: 03/26/2009
• Est. Priority Date: 09/25/2007
• Status: Abandoned Application

• Current Assignee: Silverbrook Research Pty Limited
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Tankongchumruskul, Kiangkai, Chung-Long-Shan, Laval, Williams, Susan
• Application Number:
  US12/237,387
• Publication Number:
  US 20090079097A1
• Time in Patent Office: Days
• US Class Current: 257/787
• CPC Class Codes: B41J 2/14 Structure thereof only for on-demand ink jet heads
• CPC Class Codes: B41J 2/16 Production of nozzles
• CPC Class Codes: B41J 2/1623 bonding and adhesion
• CPC Class Codes: B41J 2002/14491 Electrical connection
• CPC Class Codes: H01L 21/56 Encapsulations, e.g. encapsulation layers, coatings
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/451 with a principal constituent of the material being a metal or a metalloid, e.g. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po), and alloys thereof
• CPC Class Codes: H01L 2224/4809 Loop shape
• 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 2224/48472 the other connecting portion not on the bonding area also being a wedge bond, i.e. wedge-to-wedge
• CPC Class Codes: H01L 2224/49175 Parallel arrangements
• CPC Class Codes: H01L 2224/78313 Wedge
• CPC Class Codes: H01L 2224/85181 connecting first on the semiconductor or solid-state body, i.e. on-chip, regular stitch
• CPC Class Codes: H01L 2224/85205 Ultrasonic bonding
• CPC Class Codes: H01L 2224/859 involving monitoring, e.g. feedback loop
• CPC Class Codes: H01L 2224/8592 Applying permanent coating, e.g. protective coating
• CPC Class Codes: H01L 2224/8593 Reshaping, e.g. for severing the wire, modifying the wedge or ball or the loop shape
• CPC Class Codes: H01L 2224/85947 by mechanical means, e.g. "pull-and-cut", pressing, stamping
• CPC Class Codes: H01L 23/3157 : Partial encapsulation or coating mask layer used as insulation layer H01L21/31
• CPC Class Codes: H01L 24/45 : of an individual wire connector
• CPC Class Codes: H01L 24/48 : of an individual wire connector
• CPC Class Codes: H01L 24/49 : of a plurality of wire connectors
• CPC Class Codes: H01L 24/78 : Apparatus for connecting with wire connectors
• CPC Class Codes: H01L 24/85 : using a wire connector wire bonding in general B23K20/004
• 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 2924/00014 : 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 2924/01014 : Silicon [Si]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/09701 : Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/10253 : Silicon [Si]
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/1461 : MEMS
• CPC Class Codes: H01L 2924/15153 : the die mounting substrate comprising a recess for hosting the device
• CPC Class Codes: H01L 2924/15165 : Monolayer substrate
• CPC Class Codes: H01L 2924/20752 : larger or equal to 20 microns less than 30 microns
• CPC Class Codes: H01L 2924/20753 : larger or equal to 30 microns less than 40 microns
• CPC Class Codes: H01L 2924/20754 : larger or equal to 40 microns less than 50 microns

Abstract

An electronic component that has a support structure with a plurality of electrical conductors, a series of wire bonds, each of the wire bonds extending from one of the electrical conductors respectively, each of the wire bonds having an end section contacting the electrical conductor and an intermediate section contiguous with the end section, a bead of dam encapsulant encapsulating the electrical conductors and the end section of each of the wire bonds, and a bead of fill encapsulant contacting the bead of dam encapsulant and encapsulating the intermediate portion of each of the wire bonds. The dam encapsulant has a higher modulus of elasticity than the fill encapsulant.

Claims

1. An electronic component comprising:

a support structure with a plurality of electrical conductors;

a series of wire bonds, each of the wire bonds extending from one of the electrical conductors respectively, each of the wire bonds having an end section contacting the electrical conductor and an intermediate section contiguous with the end section;

a bead of dam encapsulant encapsulating the electrical conductors and the end section of each of the wire bonds;

a bead of fill encapsulant contacting the bead of dam encapsulant and encapsulating the intermediate portion of each of the wire bonds;

wherein,

the dam encapsulant has a higher modulus of elasticity than the fill encapsulant.

2. An electronic component according to claim 1 wherein the support structure comprises a printed circuit board (PCB) and the electrical conductors are PCB contacts connected to conductive traces on the PCB.

3. An electronic component according to claim 2 further comprising a die mounted to a chip mounting area on the support structure, the die having a back surface in contact with the chip mounting area and an active surface opposing the back surface, the active surface having electrical contact pads;

such that,

the wire bonds electrically connect the PCB contacts and the electrical contact pads on the die;

wherein,

a second bead of dam encapsulant is contiguous with the bead of fill encapsulant and encapsulates the electrical contact pads.

4. An electronic component according to claim 3 wherein the dam encapsulant has an elastic modulus between 1 GPa and 3 GPa when cured and the fill encapsulant has an elastic modulus between 10 MPa and 500 MPa when cured.

5. An electronic component according to claim 3 wherein the support structure has a PCB mounting area and the support structure is configured such that the chip mounting area is raised relative to the PCB.

6. An electronic component according to claim 5 wherein the chip mounting area is raised more than 100 microns relative to the PCB contacts.

7. An electronic component according to claim 3 wherein the support structure has a step between the chip mounting area and the conductor mounting area.

8. An electronic component according to claim 3 wherein the support structure comprises an adhesive die attach film which provides the chip mounting area.

9. An electronic component according to claim 3 wherein the PCB is a flexible printed circuit board (flex PCB) and the PCB contacts are a line of bond pads along an edge closest to the die, the bond pads being more than 2 mm from the contacts pads on the die.

10. An electronic component according to claim 1 wherein the wire bonds are formed from wire with a diameter less than 40 microns and extend less than 100 microns above the active surface of the die.

11. An electronic component according to claim 3 wherein the intermediate section of each wire bond forms an arc between the PCB contacts and the contact pads on the die, the end section of each of the wire bonds as a curved heel that connects the intermediate section to a foot segment that is welded to the PCB contact, and the second end section having a corresponding heel to connect the intermediate section to a foot segment welded to the contact pads on the die, the curved heel at the PCB contacts having a smaller radius of curvature than the corresponding heel at the contact pads of the die such that the arc of the intermediate section has a peak skewed towards the PCB.

12. An electronic component according to claim 3 wherein the active surface has functional elements spaced less than 260 microns from the contacts pads of the die. In a particularly preferred form, the die is an inkjet printhead IC and the functional elements are nozzles through which ink is ejected.

13. An electronic component according to claim 5 wherein the support structure comprises a liquid crystal polymer (LCP) molding.

14. An electronic component according to claim 3 wherein the bead of encapsulant extends less than 200 microns above the active surface of the die.

15. An electronic component according to claim 3 wherein the bead of encapsulant extends less than 100 microns above the active surface.

16. An electronic component according to claim 1 wherein the encapsulant is an epoxy material that is thixotropic when uncured.

17. An electronic component according to claim 5 wherein the encapsulant is an epoxy material with a viscosity greater than 700 cp when uncured.

18. An electronic component according to claim 3 wherein the die is a printhead IC and the active surface is an array of ink nozzles, and the support structure of configured for mounting in a printer such that during use the ink nozzles are less than 200 microns from the paper path.