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EP-4740704-A1 - ENCAPSULATION METHOD

EP4740704A1EP 4740704 A1EP4740704 A1EP 4740704A1EP-4740704-A1

Abstract

The present invention relates to a method for encapsulating an electrical component (2) arranged on a circuit board (3), comprising the steps of: providing a circuit board (3) having a first substrate layer (4) comprising or essentially consisting of a thermoplastic LCP material, wherein the first substrate layer (4) forms a top surface area (40) with the electrical component (2) arranged thereon, the electrical component (2) being electrically connected to at least one electrically conducting contact structure (5) of the circuit board (3), wherein a frame structure (6) comprising or essentially consisting of a second thermoplastic material is arranged on the top surface area (40) and particularly connected to the at least one substrate layer (4), so that a recess (60) is formed on the circuit board (3), wherein the electrical component (2) is arranged in the recess (60), and filling a third thermoplastic material in a moldable state into the recess (60) to encapsulate the electrical component in the third thermoplastic material.

Inventors

  • SCHMIDT, GREGOR
  • Hauer, Marc Robert

Assignees

  • Dyconex AG

Dates

Publication Date
20260513
Application Date
20240617

Claims (15)

  1. 1. A method for encapsulating an electrical component (2) arranged on a circuit board (3), comprising the steps of: providing a circuit board (3) having a first substrate layer (4) comprising or essentially consisting of a first thermoplastic material, particularly a first LCP material, which the first substrate layer (4) forms a top surface area (40) with the electrical component (2) arranged thereon, the electrical component (2) being electrically connected to at least one electrically conducting contact structure (5) of the circuit board (3), wherein is by a frame structure (6comprising or essentially consisting of a second thermoplastic material, particularly a second LCP material, is arranged on the top surface area (40) and particularly connected to the first substrate layer (4), wherein the frame structure at least partially surrounds the electronic component so that a recess (60) is formed on the circuit board (3), wherein the electrical component (2) is arranged in the recess (60), and filling a thermoplastic material, particularly a third LCP material, in a moldable state into the recess (60) to encapsulate the electrical component in the third thermoplastic material.
  2. 2. The method according to claim 1, wherein the frame structure (6) forms a circumferential lateral wall (61) of the recess (60).
  3. 3. The method according to claim 2, wherein the lateral wall (61) is continuous.
  4. 4. The method according to claim 2, wherein the lateral wall (61) is interrupted by one or several gaps (62), wherein particularly the respective gap 62 is at least partially filled with the third LCP material upon said filling of the third LCP material into the recess to anchor the third LCP material to the frame structure in a hardened state of the third LCP material.
  5. 5. The method according to one of the preceding claims, wherein the lateral wall (61) comprises one or several notches (62) that are filled with the third thermoplastic material upon said filling of the third thermoplastic material into the recess (60) to anchor the third thermoplastic material to the frame structure (6) in a hardened state of the third thermoplastic material.
  6. 6. The method according to one of the preceding claims, wherein the circuit board (3) comprises a circumferential outer edge (30), wherein the frame structure (6) extends up to said outer edge (30) and is flush with said outer edge or is spaced apart from said outer edge (30).
  7. 7. The method according to one of the preceding claims, wherein the first and the second thermoplastic materials are identical in their chemical or material composition or differ in their chemical composition.
  8. 8. The method according to one of the preceding claims, wherein the third thermoplastic material is identical in chemical or material composition to the first and/or second thermoplastic material, or wherein the third thermoplastic material differs in chemical composition from the first and/or second thermoplastic material.
  9. 9. The method according to one of the preceding claims, wherein the at least one electrically conducting contact structure (5) is designed in form of a conductor track, a via, and/or an electrically conducting pad.
  10. 10. The method according to one of the preceding claims, wherein the electrical component (2) is one of an integrated circuit (IC), a sensor, or a diode.
  11. 11. The method according to one of the preceding claims, wherein the frame structure (6) comprises a height (Hl) in a direction normal to the top surface area (40) that is equal to or larger than a height (H2) of the electrical component (2) in the same direction.
  12. 12. The method according to one of the preceding claims, wherein the frame structure (6) is generated prior to said filling of the third thermoplastic material in the recess (60), wherein the frame structure is generated by dispensing the third thermoplastic material in a flowable state onto the at least one substrate layer (4) using a first dispensing device (7).
  13. 13. The method according to one of the preceding claims, wherein the filling of said recess (60) with the third thermoplastic material is conducted by the first dispensing device (7) or by a separate second dispensing device (8).
  14. 14. The method according to one of the preceding claims, wherein the third thermoplastic material after having been filled into the recess is then pressed into a defined shape by means of a stamping tool (9).
  15. 15. A circuit board assembly comprising circuit board (3) having a first substrate layer (4) comprising or essentially consisting of a first thermoplastic material, particularly a first LCP material, which the first one substrate layer (4) forms a top surface area (40) with the electrical component (2) arranged thereon, the electrical component (2) being electrically connected to at least one electrically conducting contact structure (5) of the circuit board, wherein a frame structure (6) comprising or essentially consisting of a second thermoplastic material, particularly a second LCP material, is arranged on the top surface area (40) and particularly connected to the first substrate layer (4), so that a recess (6) is formed on the circuit board (3), wherein the electrical component (2) is arranged in the recess (60), wherein a third thermoplastic material, particularly a third LCP material, is arranged in the recess (60) encapsulates the electrical component (2).

Description

Encapsulation Method The present invention relates to a method for encapsulating an electrical component arranged on a circuit board, particularly printed circuit board, and a circuit board assembly. US 2004/0262782 Al discloses encapsulated, overmolded and/or underfilled electrical components having a complete encapsulation, wherein overmolding and/or underfilling with a coefficient of thermal expansion that is uniform and substantially free of gradients includes a polymeric matrix and an inorganic filler having a platelet geometric structure. The platelet structure of the filler allows a desirable coefficient of thermal expansion to be achieved using a very low level of filler material. This low level of filler material facilitates lower viscosity during forming of the encapsulation and/or overmolding, thereby facilitating complete filling of a mold cavity and underfilling of space between a circuit board and a semi-conductor chip electrically connected to the circuit board. Furthermore, encapsulation in thermoplastics, e.g., LCP (liquid crystal polymer), by pressing in film structures is known in the art, wherein however, depending on the product, the films have to be extensively recessed and registered. Further, such films may have limited adhesion values after pressing, thus interfaces may remain, which may weaken the diffusion barrier. Furthermore, such films are only available in certain thicknesses, which means that the structures often cannot be adapted as required. Further, the films may flow after pressing, resulting in an undefined shape in some cases. Furthermore, encapsulation of electronic components based on the dam and fill process is generally known in the art. Here, dosing of liquid, mostly UV-curing adhesive systems is performed to encapsulate the respective component. This is a common packaging method. However, the afore-described materials are usually not biocompatible which is mandatory for applications in implantable medical devices. Furthermore, there is a fundamental risk inherent in a build-up with different materials (different mechanical properties, expansion coefficients, etc.). Furthermore, standard dam and fill processes are also limited in the amount of packaging possible. Based on the above, the problem to be solved by the present invention is to provide a method for encapsulating an electrical component that is cost effective and helps to realize a high- quality encapsulation of components that can be easily adapted to the dimensions of the product. This problem is solved by a method having the features of claim 1 and a circuit board assembly having the features of claim 15. Preferred embodiments of these aspects of the present invention are stated in the corresponding dependent claims and are described below. According to claim 1, a method for encapsulating an electrical component arranged on a circuit board is disclosed, the method comprising the steps of: - providing a circuit board having at least one substrate layer comprising or essentially consisting of a first thermoplastic material, which substrate layer forms a top surface area with the electrical component arranged thereon, the electrical component being electrically connected to at least one electrically conducting contact structure of the circuit board, wherein a frame structure comprising or essentially consisting of a second thermoplastic material is arranged on the top surface area and particularly connected to the at least one substrate layer, wherein the frame structure at least partially surrounds the electrical component so that a recess is formed on the circuit board, wherein the electrical component is arranged in the recess, and - filling a third thermoplastic material in a flowable state into the recess to encapsulate the at least one electrical component in the third LCP material. In one embodiment, the first thermoplastic material is a first LCP material. In one embodiment, the second thermoplastic material is a second LCP material. In one embodiment, the third thermoplastic material is a third LCP material. In one embodiment, the third thermoplastic material is provided in a flowable state by heating, i.e., by melting the third thermoplastic material into a molten state. In one embodiment, the third thermoplastic material, particularly the third LCP material, is provided in flowable state by heating the third thermoplastic material to a temperature in the range of 250°C to 400°C, and particularly filled into the recess having a temperature in the range of 250°C to 400°C. In one embodiment, prior to and/or during filling the third thermoplastic material, particularly the third LCP material, in a flowable state into the recess, the circuit board is heated, particularly to a temperature in the range of 100°C to 200°C. Advantageously, by heating the circuit board prior to and/during filling the third thermoplastic material, particularly the third LCP material, the circuit board is soften to impro