Means and process for encapsulating electric circuits by means of injection molding

• US 6,340,791 B1
• Filed: 08/23/1999
• Issued: 01/22/2002
• Est. Priority Date: 08/22/1998
• Status: Expired due to Fees

• Current Assignee: Mannesmann VDO AG (Continental AG)
• Original Assignee: Mannesmann VDO AG (Continental AG)
• Inventors: Stotz, Oliver
• Primary Examiner(s): BERHANE, ADOLF D
• Application Number:
  US09/379,473
• Time in Patent Office: 883 Days
• Field of Search: 174/52.1, 174/50, 174/52.2, 174/52.3, 174/52.4, 174/52.5
• US Class Current: 174/521
• CPC Class Codes: B29C 45/0046 Details relating to the filling pattern or flow paths or flow characteristics of moulding material in the mould cavity
• CPC Class Codes: B29C 45/14639 for obtaining an insulating effect, e.g. for electrical components
• CPC Class Codes: B29C 45/14836 Preventing damage of inserts during injection, e.g. collapse of hollow inserts, breakage B29C45/14434 takes precedence
• CPC Class Codes: H05K 3/284 for encapsulating mounted components H05K1/185 takes precedence

Abstract

A means and a process for protecting an electric circuit from ambient influences, the circuit being surrounded with a thermoplastic polymer which is applied by injection molding, the thermoplastic polymer comprising oriented macromolecules. The components of the circuit are aligned with their axis most sensitive to alternating tensile loading on average parallel to the respective direction of flow of the injected polymer in the vicinity of the components.

Claims

1. A structure for protecting an electric circuit comprising:

a circuit surrounded with a thermoplastic polymer which is applied by injection molding, wherein the thermoplastic polymer is comprised of oriented macromolecules and wherein a majority of the components of the circuit are aligned with their axis most sensitive to alternating tensile loading being parallel to the respective direction of the macromolecules present in the vicinity of the components.

2. The structure of claim 1, wherein the polymer is a thermotropic liquid-crystalline polymer.

3. The structure of claim 1, wherein the circuit is secured within a solid support housing, said housing forming at least part of the injection mold for the thermoplastic polymer.

4. The structure of claim 1, wherein a formation of conductor tracks is at least partially embedded in a first layer of the polymer, wherein the components of the circuit are connected to the conductor tracks that are not covered by the first polymer layer and wherein the circuit is surrounded by a second layer of the polymer.

5. The structure as claimed in claim 4, wherein the first polymer layer has molded parts to which the components of the circuit are fastened.

6. The structure as claimed in claim 1, wherein the circuit is applied to a solid support, produced by injection molding, which is comprised of the polymer, and wherein the circuit together with the support is surrounded by the polymer.

7. The structure as claimed in claim 6, wherein the conductor tracks of the circuit are applied to the support by hot embossing.

8. The structure as claimed in claim 6, wherein the conductor tracks of the circuit are electroplated onto the support.

9. A process for protecting an electric circuit comprising the steps of:

prior to encapsulation, arranging a majority of the components of a circuit such that their axis which is most sensitive to alternating tensile loading is at least substantially parallel to a principal direction of orientation; and

thereafter surrounding the circuit with a thermoplastic polymer via injection molding such that the orientation of the macromolecules of the polymer is at least substantially parallel to the principal direction of the orientation.

10. The process as claimed in claim 9, further comprising a step of inserting the circuit into a housing;

closing the housing with a cover and subsequently filling the housing with the polymer.

11. The process as claimed in claim 10, further comprising a step of removing the cover after encapsulation.

12. The process as claimed in claim 9, further comprising a step of attaching conductor tracks of the circuit to a solid support;

connecting components of the circuit to the conductor tracks; and

surrounding the components with the polymer.

13. The process as claimed in claim 9, further comprising a step of partially surrounding the conductor tracks with the polymer, wherein connection contacts for the components of the circuit are free of polymer;

and connecting the components to the connection contacts and thereafter surrounding the components with the polymer.

14. The method of claim 9, wherein a substantial a majority of the components of the circuit are arranged such that their axis which is most sensitive to alternating tensile loading is at least substantially parallel to a principal direction of orientation.

15. the method of claim 9, wherein all of the components of the circuit are arranged such that their axis which is most sensitive to alternating tensile loading is at least substantially parallel to a principal direction of orientation.

16. A structure for protecting an electric circuit comprising:

a circuit surrounded with a thermoplastic polymer which is applied by injection molding, wherein the thermoplastic polymer is comprised of oriented macromolecules and wherein a majority of the components of the circuit are aligned with their axis most sensitive to alternating tensile loading being parallel to the respective direction of the macromolecules present in the vicinity of the components.

17. A structure for protecting an electric circuit of claim 16, wherein a substantial majority of the components of the circuit are aligned with their axis most sensitive to alternating tensile loading being parallel to the respective direction of macromolecules.

18. A structure for protecting an electric circuit of claim 16, wherein all of the components of the circuit are aligned with their axis most sensitive to alternating tensile loading being parallel to the respective direction of macromolecules.