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A Simplified Manufacturing Process for Planar Transformers

IP.com Disclosure Number: IPCOM000248295D
Publication Date: 2016-Nov-15
Document File: 4 page(s) / 92K

Publishing Venue

The IP.com Prior Art Database

Abstract

This paper describes a new process for making planar transformers using an electrically insulated, thermally curing double coated tape. This new process replaces a single coated polyimide (PI) or Nomex tape with this double-coated tape as an insulator between a copper plate and/or PCB coils. The varnish steps in the current process will no longer be necessary and energy, labor and raw materials costs will be decreased. The traditional manufacturing process can be simplified and planar transformer thicknesses can be reduced.This paper describes a new process for making planar transformers using an electrically insulated, thermally curing double coated tape. This new process replaces a single coated polyimide (PI) or Nomex tape with this double-coated tape as an insulator between a copper plate and/or PCB coils. The varnish steps in the current process will no longer be necessary and energy, labor and raw materials costs will be decreased. The traditional manufacturing process can be simplified and planar transformer thicknesses can be reduced.

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Page 01 of 4

A simplified manufacturing process for planar transformers

This paper describes a new process for making planar transformers using an electrically insulated, thermally curing double coated tape. This new process replaces a single coated polyimide (PI) or Nomex tape with this double- coated tape as an insulator between a copper plate and/or PCB coils. The varnish steps in the current process will no longer be necessary and energy, labor and raw materials costs will be decreased. The traditional manufacturing process can be simplified and planar transformer thicknesses can be reduced.

Background

In response to the trend for reduced size in the electronic industry and due to their other advantageous properties, planar transformers are becoming more and more widely used in telecommunications, power supplies, the automotive industry, consumer electronics, etc.

Planar transformers eliminate virtually all the shortcomings of old-fashioned wire wound types of transformers. In a planar design, the windings are made of copper foil frames or printed circuit boards. These windings are then stacked like a sandwich, along with the appropriate insulators, between large area and thin ferrite cores. This special construction technique yields benefits as:


- High efficiency (up to 98%)

- Low leakage inductance

- Low profile, small volume, for high power density equipment designs.
- Wide working frequency range: 50kHz to 1MHz.
- 10W - 20kW power ratings.

- Efficient heat dissipation and cooling

- Low weight: 15g per 100W

- Minimal Electromagnetic Interference (EMI).

- Wide Operating temperature range: -40°C to +155°C.

Current copper foil frames in planar transformers are typically made from insulators such as Nomex, PI film or PI tape. Generally, a long process is necessary for such designs.

In this system, a double coated, thermal curing tape is designed with benefits described below.

a. By reducing the insulator thickness from 0.14-0.20 mm to 0.10 mm, it provides the capability for lower profile
design.

b. With a higher bonding strength (>9.0N/10mm) than general PSA tape (2.0-5.0N/10mm), the planar transformer structure will be more stable.


c. The process can be shortened and raw materials can be reduced, as indicated in red in Figure 1.

E ferrite core

Copper plate or PCB coil Nomex or PI or PI tape

Assembly

Dispense

Assembly

Adhesive

Ferrite core

 Vacuum immersing

Varnish drain

Adhesive curing

120-150x1-2h

Preheating

100x1-2h

Varnish

Varnish curing

120-150x1-2h

Test Marking Packing

Finished parts

  Figure 1. A typical planar transformer manufacturing process. Red items indicate raw materials and process steps that can be eliminated by using a thermally curing, double coated electrical insulation tape.


Page 02 of 4

Description and Examples


1.Raw materials and sample for thermal curing, double coated tape

Composition Material Remar...