Insert injection-compression molding of polymeric PTC electrical devices

• US 20060157891A1
• Filed: 01/11/2006
• Published: 07/20/2006
• Est. Priority Date: 01/14/2005
• Status: Abandoned Application

• Current Assignee: Littelfuse Incorporated
• Original Assignee: Tyco Electronics Corporation (TE Connectivity Limited)
• Inventors: Matthiesen, Martin, Sparks, Bruce J., Hardy, Joseph T., Hansen, Erling, Vranicar, Anthony
• Application Number:
  US11/330,694
• Publication Number:
  US 20060157891A1
• Time in Patent Office: Days
• US Class Current: 264/261
• CPC Class Codes: B29C 2045/14532 injecting between two sheets
• CPC Class Codes: B29C 45/14467 Joining articles or parts of a single article B29C45/14377, B29C45/14385, B29C45/14581, B29C45/14614 and B29C45/006 take precedence
• CPC Class Codes: B29C 45/561 Injection-compression moulding
• CPC Class Codes: H01C 17/28 adapted for applying terminals
• CPC Class Codes: H01C 7/003 Thick film resistors
• CPC Class Codes: H01C 7/027 consisting of conducting or semi-conducting material dispersed in a non-conductive organic material

Abstract

A method for making an individual PPTC electrical circuit protection device includes steps of inserting two surface-treated conductive electrodes into a mold; injecting plastic-phase PPTC material into a space between the two electrodes; closing the mold and thereby applying pressure to the electrodes and PPTC material to form a completed device; and removing the completed device from the mold. Mold temperature is controlled in a range of between 80 and 125° C.

Claims

1. A method for making an individual PPTC electrical circuit protection device comprising steps of:

(a) inserting two surface-treated conductive electrodes into a mold;

(b) injecting plastic-phase PPTC material into a space between the two electrodes;

(c) closing the mold and thereby applying pressure to the electrodes and PPTC material to form a completed device; and

(d) removing the completed device from the mold.

2. The method set forth in claim 1 comprising the step of heating the mold to a temperature in a range between 80°

C. and 125°

C. before the step of closing the mold.

3. The method set forth in claim 2 comprising the step of cooling the mold and the completed device prior to the step of removing the completed device from the mold.

4. The method set forth in claim 1 wherein the two surface treated conductive electrodes comprise metal plates having a thickness at least 0.127 mm (0.005 inch).

5. The method set forth in claim 1 wherein the two surface treated conductive electrodes comprise metal foils having a thickness not greater than 0.5 mm (0.020 inch).

6. A method for making a PPTC resistive device without using metal foils including steps of:

(a) inserting metal electrode plates having predetermined thicknesses at least equal to 0.127 mm (0.005 inch) and having oppositely facing major surfaces modified for good adhesion into opposite sides of a mold cavity defined by a mold;

(b) injecting a controlled amount of PPTC material in plastic phase into the mold cavity;

(c) closing the mold cavity and compressing the PPTC material to occupy a predetermined thickness between the two metal electrodes and to engage the oppositely facing major surfaces of the metal electrode plates; and

(d) opening the mold and thereupon ejecting the PPTC resistive device having the electrodes integrally attached thereto.

7. The method set forth in claim 6 wherein the oppositely facing major surface of the metal electrode plates are processed by steps of:

(e) chemically etching the major surface to provide a roughened surface; and

(f) depositing metal, e.g. by electroplating, to grow dendrite-like nodules on the roughened surface.

8. The method set forth in claim 6 comprising the step of heating the mold to a temperature in a range between 80°

C. and 125°

C. before the step of closing the mold.