Method for manufacturing surface mount conductive polymer devices

• US 5,802,709 A
• Filed: 04/16/1997
• Issued: 09/08/1998
• Est. Priority Date: 08/15/1995
• Status: Expired due to Fees

• Current Assignee: Bourns, Multifuse (Hong Kong), Ltd.
• Original Assignee: Bourns, Multifuse (Hong Kong), Ltd.
• Inventors: Straker, Gary, Zhang, Mengruo, Wisner, Duane, Gratzinger, Paul G., Hogge, Steven Darryl
• Primary Examiner(s): Arbes, Carl J.
• Application Number:
  US08/838,210
• Time in Patent Office: 510 Days
• Field of Search: 29/827, 156/324, 174/55.4, 338/324
• US Class Current: 29/827
• CPC Class Codes: B29C 2948/92019 Pressure
• CPC Class Codes: B29C 2948/92152 Thickness
• CPC Class Codes: B29C 2948/9238 Feeding, melting, plasticising or pumping zones, e.g. the melt itself
• CPC Class Codes: B29C 2948/92438 Conveying, transporting or storage of articles
• CPC Class Codes: B29C 2948/92466 Auxiliary unit, e.g. for external melt filtering, re-combining or transfer between units
• CPC Class Codes: B29C 2948/926 Flow or feed rate
• CPC Class Codes: B29C 2948/92647 Thickness
• CPC Class Codes: B29C 2948/92828 Raw material handling or dosing, e.g. active hopper or feeding device
• CPC Class Codes: B29C 2948/92952 Drive section, e.g. gearbox, motor or drive fluids
• CPC Class Codes: B29C 48/07 Flat, e.g. panels
• CPC Class Codes: B29C 48/92 Measuring, controlling or regulating
• CPC Class Codes: B29K 2995/0005 Conductive
• CPC Class Codes: B32B 2309/10 linear, e.g. length, distance, width
• CPC Class Codes: B32B 2309/72 For measuring or regulating, e.g. systems with feedback loops
• CPC Class Codes: B32B 37/153 at least one layer is extruded and immediately laminated while in semi-molten state
• CPC Class Codes: H01C 1/028 the resistive element being embedded in insulation with outer enclosing sheath
• CPC Class Codes: H01C 1/1406 Terminals or electrodes formed on resistive elements having positive temperature coefficient
• CPC Class Codes: H01C 7/027 consisting of conducting or semi-conducting material dispersed in a non-conductive organic material
• CPC Class Codes: Y10T 29/49121 Beam lead frame or beam lead device

Abstract

A conductive polymer device includes an active element comprising a conductive polymeric layer laminated between a pair of electrodes to which terminal leads are attached. The active element is enclosed in an insulative package. Each of the electrodes may be formed integrally with its associated terminal lead in a single lead frame, with a layer of conductive polymeric material laminated between two such lead frames. Alternatively, a conductive polymeric layer may be laminated between two electrodes, with a terminal lead then being soldered to each electrode. The insulative package for the active element may be either an over-molded housing encasing the active element, or a pre-molded housing having a cavity into which the active element is installed, and which is then hermetically sealed with a suitable sealant material.

Claims

1. A method of making an electronic device, comprising the steps of:

providing a first length of conductive metal foil having a peripheral edge formed as a first carrier strip;

providing a second length of conductive metal foil having a peripheral edge formed as a second carrier strip;

laminating a layer of conductive polymeric material between the first and second lengths of conductive metal foil to form a laminated strip having the first and second carrier strips along opposed edges;

forming the laminated strip into a plurality of active elements, each comprising a layer of conductive polymer material sandwiched between a first planar metal foil electrode connected to the first carrier strip by a first terminal lead element and a second planar metal foil electrode connected to the second carrier strip by a second terminal lead element;

enclosing each of the active elements in an insulative package; and

separating the first and second terminal lead elements from the first and second carrier strips, respectively.

2. The method of claim 1, wherein the enclosing step comprises the step of overmolding a conformal housing around each of the active elements.

3. The method of claim 1, wherein the enclosing step comprises the steps of:

for each of the active elements, providing a pre-molded housing having a cavity;

inserting an active element into the cavity of each of the pre-molded housings; and

hermetically sealing each cavity with sealing material placed in the cavity around the active element.

4. A method of making an electronic device, comprising the steps of:

providing a laminated strip comprising a conductive polymer layer sandwiched between first and second metal layers;

providing a first lead frame comprising a first plurality of lead members connected to a first carrier strip;

providing a second lead frame comprising a second plurality of lead members connected to a second carrier strip;

attaching the first plurality of lead members to the first metal layer;

attaching the second plurality of lead members to the second metal layer;

forming the laminated strip into a plurality of active elements, each comprising a conductive polymer layer sandwiched between a first electrode formed from the first metal layer and a second electrode formed from the second metal layer, the first electrode being attached to the first carrier strip by one of the first plurality of lead elements and the second electrode being attached to the second carrier strip by one of the second plurality of lead elements;

enclosing each of the active elements in an insulative package; and

separating the first and second lead elements from the first and second carrier strips, respectively.

5. The method of claim 4, wherein the enclosing step comprises the step of overmolding a conformal housing around each of the active elements.

6. The method of claim 4, wherein the enclosing step comprises the steps of:

for each of the active elements, providing a pre-molded housing having a cavity;

inserting an active element into the cavity of each of the pre-molded housings; and

hermetically sealing each cavity with sealing material placed in the cavity around the active element.

7. The method of claim 4, wherein the attaching steps are performed by soldering.

8. The method of claim 5, wherein the attaching steps are performed by soldering.

9. The method of claim 6, wherein the attaching steps are performed by soldering.

10. A method of making an electronic device, comprising the steps of:

providing a laminated strip comprising a conductive polymer layer sandwiched between first and second metal layers;

forming the laminated strip into a plurality of active elements, each comprising a conductive polymer layer sandwiched between a first electrode formed from the first metal layer and a second electrode formed from the second metal layer, the first electrode being attached to the first carrier strip by one of the first plurality of lead elements and the second electrode being attached to the second carrier strip by one of the second plurality of lead elements;

providing a first lead frame comprising a first plurality of lead members connected to a first carrier strip;

providing a second lead frame comprising a second plurality of lead members connected to a second carrier strip;

attaching each of the first plurality of lead members to the first electrode of one of the active elements;

attaching each of the second plurality of lead members to the second electrode of one of the active elements;

enclosing each of the active elements in an insulative package; and

separating the first and second lead elements from the first and second carrier strips, respectively.

11. The method of claim 10, wherein the enclosing step comprises the step of overmolding a conformal housing around each of the active elements.

12. The method of claim 10, wherein the enclosing step comprises the steps of:

for each of the active elements, providing a premolded housing having a cavity;

inserting an active element into the cavity of each of the pre-molded housings; and

hermetically sealing each cavity with sealing material placed in the cavity around the active element.

13. The method of claim 10, wherein the attaching steps are performed by soldering.

14. The method of claim 11, wherein the attaching steps are performed by soldering.

15. The method of claim 12, wherein the attaching steps are performed by soldering.