Method for applying a structured coating to a component

• US 9,556,022 B2
• Filed: 05/12/2014
• Issued: 01/31/2017
• Est. Priority Date: 06/18/2013
• Status: Active Grant

• Current Assignee: TDK Corporation
• Original Assignee: Epcos AG (TDK Corporation)
• Inventors: Pahl, Wolfgang
• Primary Examiner(s): HENRY, CALEB E
• Application Number:
  US14/970,749
• Publication Number:
  US 20160297676A1
• Time in Patent Office: 995 Days
• Field of Search: 438/51
• US Class Current: 1/1
• CPC Class Codes: B81B 2201/0257 Microphones or microspeakers
• CPC Class Codes: B81B 2203/0127 Diaphragms, i.e. structures separating two media that can control the passage from one medium to another; Membranes, i.e. diaphragms with filtering function
• CPC Class Codes: B81B 2207/012 the micromechanical device and the control or processing electronics being separate parts in the same package
• CPC Class Codes: B81B 2207/115 Protective layers applied directly to the device before packaging
• CPC Class Codes: B81B 7/0058 for protecting against damages due to external chemical or mechanical influences, e.g. shocks or vibrations
• CPC Class Codes: B81C 1/00825 Protect against mechanical threats, e.g. against shocks, or residues B81C1/00261 take precedence
• CPC Class Codes: B81C 2201/053 Depositing a protective layers
• CPC Class Codes: B81C 2203/0785 Transfer and j oin technology, i.e. forming the electronic processing unit and the micromechanical structure on separate substrates and joining the substrates
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/73257 Bump and wire connectors
• CPC Class Codes: H01L 2924/16151 Cap comprising an aperture, e.g. for pressure control, encapsulation
• CPC Class Codes: H01L 2924/16152 Cap comprising a cavity for hosting the device, e.g. U-shaped cap

Abstract

For producing a structured coating, or for carefully lifting off a coating over a sensitive region, it is proposed that a release film be applied and structured under the coating in the region which is not to be coated. In a release step, the release film is reduced in the adhesion in the region which is not to be coated and is subsequently lifted off together with the coating applied over it.

Claims

1. A method for applying a structured coating to a structural element with a surface having a coating region and an uncoated region, comprising:

a. wherein a release film is applied to the coating region of the structural element and is at least partially fixed inside the uncoated region,

b. wherein the release film is removed from the coating region,

c. wherein a coating is applied over the entire area over the release film and the surface of the structural element,

d. wherein the coating is severed circumferentially around the coating region along a second partition line,

e. wherein the adhesion of the release film is reduced at least in the region enclosed by the second partition line,

f. wherein the release film together with the coating applied over the release film is lifted off in the uncoated region.

2. The method according to claim 1,

wherein a UV release tape or a thermal release tape is used as the release film and the adhesion of the release film is reduced in method step e) by means of UV light, laser, or by thermal action.

3. The method according to claim 1,

wherein the structural element is part of an assembly having one or more MEMS or chip components that are arranged on a carrier, wherein the structural element represents one of MEMS or chip components,

wherein the release film is applied over the entire area over the assembly as the coating so that the release film either seals off each of the MEMS or chip components or the components as a whole as an assembly from the carrier,

wherein a media access to the MEMS component is provided in the uncoated region.

4. The method according to claim 3,

wherein in method step a), the release film is applied to a MEMS wafer, in which a plurality of MEMS components are processed in parallel,

wherein method step b) is then carried out,

wherein the MEMS components are singulated,

wherein subsequently the assembly is equipped with at least one of the MEMS components and at least one chip component,

wherein subsequently method steps c) to f) are carried out.

5. The method according to claim 1,

wherein in method step b), incisions are created in the release film along a first partition line around the uncoated region and the release film is removed in the coating region outside the region enclosed by the first partition line,

wherein then the coating is applied,

wherein the adhesion of the release film is first reduced thermally or by the action of UV radiation in the entire uncoated region in method step e) and then second incisions are created in the coating in method step d) along the second partition line.

6. The method according to claim 1,

wherein the structural element is a MEMS microphone, which is mounted alone or in an assembly on a carrier,

wherein, in method step f), a recess is exposed above a microphone membrane in the microphone in the uncoated region,

wherein a cover is fastened on the carrier over the MEMS microphone or the assembly so that a cavity which accommodates the MEMS microphone or the assembly is enclosed and sealed off under the cover,

wherein for this purpose either a flat carrier is used and a cap is applied thereon as a cover, or wherein a trough-shaped carrier is used and a flat cover is applied over it,

wherein a sound opening is provided in the cover or the carrier.

7. The method according to claim 6,

wherein a volume above the microphone membrane is sealed off from a volume below the membrane using the coating, wherein the volume over the membrane comprises the remaining cavity above the coating and under the cover,

wherein the volume below the coating and below the microphone membrane comprises at least one intermediate space that is sealed by the coating to the carrier between MEMS and/or chip components.

8. The method according to claim 6,

wherein, in method step c), a film which can be deep drawn is applied over the assembly as the coating.

9. The method according to claim 3,

wherein, in method steps b) and f), the release film is not removed in a bridge region above the intermediate space between two components of the assembly,

wherein, during and after method step c), the release film remaining in the bridge region supports the coating above the intermediate space.

10. The method according to claim 3,

wherein a thermal release tape is used as the release film after the mounting of the components on the carrier,

wherein, in method step e), the adhesion of the entire remaining release film is reduced by thermal action,

wherein the lifting off of the release film together with coating applied over the release film in the uncoated region is achieved by blowing off, suctioning off, or by drawing off using an adhesive film.

11. The method according to claim 3, wherein, in method step c), a film which can be deep drawn and thermally cured is applied over the assembly as the coating.

12. The method according to claim 6,

wherein the coating on the carrier is removed except for an edge region that is adjacent to the assembly and completely encloses the assembly, wherein the coating terminates closely with the carrier in the entire edge region,

wherein the cap is placed on the region of the carrier free from the coating and is glued to the carrier.

13. The method according to claim 6,

wherein the MEMS microphone is mounted according to flip-chip technology on the carrier,

wherein the sound opening in the cap is provided above an intermediate space between two components,

wherein, between the cap and the coating over the assembly, a seal is used to seal around the sound opening from the inside with the cap,

wherein an opening is provided in the seal below the sound opening,

wherein the opening is extended through the coating into the intermediate space, so that a continuous sound channel is opened through the sound opening, the seal, and the coating into the intermediate space down to below the MEMS component.

14. The method according to claim 13,

wherein the seal is applied as a viscous compound through the sound opening after the placement of the cap and is subsequently cured.

15. The method according to claim 13, wherein the seal is arranged above the intermediate space before the placement of the cap on the coating.

16. The method according to claim 15,

wherein a sealing ring made of elastic material is arranged on the coating above the intermediate space as the seal.

17. The method according to claim 13,

wherein the seal is applied as a viscous compound that is elastic in the cured state, the seal being applied into the intermediate space between coating and the cap in the region of the sound opening so that the seal solidly closes the sound opening and seals the edges thereof from the coating,

wherein the opening in the seal and in the coating is subsequently created by laser drilling.

18. A method of applying a coating to a structural element having a coating region and an uncoated region, comprising:

applying a release film to the coating region and at least partially within the uncoated region;

removing the release film from the coating region such that the release film remains in the uncoated region;

applying the coating over the structural element in the coating region and the uncoated region;

severing the coating circumferentially around the coating region along a partition line between the coating region and the uncoated region;

reducing an adhesion of the release film within the uncoated region; and

after the reducing, removing the release film together with the coating applied over the release film from the uncoated region.

19. The method according to claim 18, wherein the structural element is a MEMS component that is part of an assembly arranged on a carrier, and wherein the applying the release film includes sealing off a recess region of the MEMS component on the carrier with the release film, the recess region being the uncoated region.

20. The method according to claim 18, wherein the release film is a UV-release tape or a thermal-release tape and the reducing the adhesion of the release film is accomplished by exposing the release film to UV light, a laser, or thermal action.