Inkjet printhead with encapsulant-retaining features

Patent metadata

Field	Value
Publication number	US-10864733-B2
Application number	US-201916400949-A
Country	US
Kind code	B2
Filing date	May 1, 2019
Priority date	May 3, 2018
Publication date	Dec 15, 2020
Grant date	Dec 15, 2020

Abstract

A MEMS chip assembly including: a support structure having a chip mounting surface; a MEMS chip mounted on the chip mounting surface, each MEMS chip having an active surface including one or more MEMS devices and a plurality of bond pads disposed alongside a connection edge of the MEMS chip; electrical connectors connected to the bond pads; and an encapsulant material covering the electrical connectors. The MEMS chip has encapsulant-retaining trenches defined in the active surface extending alongside the connection edge, each encapsulant-retaining trench being disposed between the bond pads and the MEMS devices.

First claim

The invention claimed is:

1. A MEMS chip assembly comprising:
a support structure having a chip mounting surface;
a MEMS chip mounted on the chip mounting surface, each MEMS chip having an active surface including one or more rows of MEMS devices and a row of bond pads disposed alongside a connection edge of the MEMS chip and parallel with the rows of MEMS devices;
electrical connectors connected to the bond pads; and
an encapsulant material covering the electrical connectors,

wherein:
the MEMS chip has multiple rows of encapsulant-retaining trenches defined in the active surface;
the multiple rows of encapsulant-retaining trenches extend parallel with the rows of MEMS devices;
a distance between neighboring encapsulant-retaining trenches is greater than a width of each encapsulant-retaining trench;
the multiple rows of encapsulant-retaining trenches are disposed between the bond pads and the MEMS devices; and
the encapsulant material does not encroach past the encapsulant-retaining trenches towards the MEMS devices.

2. The MEMS chip assembly of claim 1 , wherein the electrical connectors comprise wirebonds or TAB connections.

3. The MEMS chip assembly of claim 1 , wherein the rows of encapsulant-retaining trenches extend parallel with the connection edge.

4. The MEMS chip assembly of claim 1 , wherein each encapsulant-retaining trench has a depth in the range of 2 to 10 microns and a width in the range of 2 to 20 microns.

5. The MEMS chip assembly of claim 1 , wherein each encapsulant-retaining trench has a rectangular profile in cross-section.

6. The MEMS chip assembly of claim 1 , wherein the encapsulant material is a polymer applied as a liquid during encapsulation.

7. The MEMS chip assembly of claim 1 , wherein the MEMS devices are inkjet nozzle devices and the support structure is a fluid manifold for delivering ink to the inkjet nozzle devices.

8. A MEMS chip comprising a substrate having an active surface, the active surface including:
a plurality of rows of MEMS devices; and
a row of bond pads arranged alongside a connection edge of the substrate and parallel with the rows of MEMS devices; and

wherein:
the MEMS chip has multiple rows of encapsulant-retaining trenches defined in the active surface;
the multiple rows of encapsulant-retaining trenches extend parallel with the rows of MEMS devices;
a distance between neighboring encapsulant-retaining trenches is greater than a width of each encapsulant-retaining trench; and
the multiple rows of encapsulant-retaining trenches are disposed between the bond pads and the MEMS devices.

9. The MEMS chip of claim 8 , wherein the rows of encapsulant-retaining trenches extend parallel with the connection edge.

10. The MEMS chip of claim 8 , wherein each encapsulant-retaining trench has a depth in the range of 2 to 10 microns and a width in the range of 2 to 20 microns.

11. The MEMS chip of claim 8 , wherein the MEMS devices are inkjet nozzle devices.

12. A method of fabricating a MEMS chip assembly, said method comprising the steps of:
mounting a MEMS chip according to claim 8 to a chip mounting surface of a support structure;
connecting electrical connectors to the row of bond pads;
applying one or more beads of liquid encapsulant material over the electrical connectors;
pinning an advancing liquid front of the encapsulant material at an edge of one of the encapsulant-retaining trenches defined in the active surface; and
curing the encapsulant material.

13. The method of claim 12 , wherein the multiple encapsulant-retaining trenches minimize encroachment of the encapsulant material onto the MEMS devices.

14. The method of claim 12 , wherein the encapsulant material is a liquid polymer.

15. The method of claim 12 , wherein the rows of encapsulant-retaining trenches extends parallel with a longitudinal edge of the MEMS chip.

16. The method of claim 12 , wherein the MEMS chip is a printhead chip and the MEMS chip assembly is an inkjet printhead.

Assignees

• Memjet Technology Ltd

Inventors

• Perez Elmer Dimaculangan
• North Angus
• Lowe Graeme
• Tan See-Huat
• Barton Christopher

Classifications

• B41J2/04541

  Specific driving circuit · CPC title

• B41J2/14024

  Assembling head parts · CPC title

• B41J2002/14491

  Electrical connection · CPC title

• B41J2202/20

  Modules · CPC title

• B41J2/14072

  Electrical connections, e.g. details on electrodes, connecting the chip to the outside... · CPC title