GB2110162A

GB2110162A - A method of producing electrically conductive areas

Info

Publication number: GB2110162A
Application number: GB08229690A
Authority: GB
Inventors: Dr Klaus Brill; Dr Werner Grunwald; Dr Gerhard Holfelder; Kurt Schmid
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1981-11-17
Filing date: 1982-10-18
Publication date: 1983-06-15
Also published as: JPS5891695A; GB2110162B; FR2516740A1

Abstract

A method is proposed for producing electrically conductive areas in which an electrically conductive paste is applied by means of a rotating, elastically deformable die (21) in a printing process to predetermined areas of a carrier (15). The method in accordance with the invention can be used with particular advantage for printing curved surfaces, particularly of electro-chemical metering sensors (15) for determining the oxygen content in gases. <IMAGE>

Description

SPECIFICATION A method of producing electrically conductive areas The invention originates from a method for producing electrically conducting areas according to the preamble to the main claim. Known methods for producing surface patterns are carried out by a method of application by rolling or by brushing.

Moreover, screen printing methods are known for applying electrically conductive patterns. Furthermore, a method is known from German OS 30 14 877 forthe application of an exhaust gas-oxygensensor electrode (Lamba-probe) in which an electrically conductive liquid or paste is metered, is located in a cavity and is distributed in the cavity by means of an inflatable finger-like member. German AS 17 71 551 describes a method for printing electrical circuits on a substrate in which a conductive paste is applied to a substrate by a translatory movement of an elastic transfer device. The production of large area patterns on curved surfaces also involves difficulties with this method.Finally, electrically conductive pastes of the type in question are known, for example from German OS 29 13633 andlor from German OS 30 02 112. The known methods are to some extent very expensive as regards manufacturing techniques, on the other hand they are not suitable for expensive conductive pastes comprising a a high precious metal content since they only provide a minimum quantity of paste to be applied with difficulty.

As opposed to this, the method in accordance with the invention comprising the characterising features of the main claim has the advantage that practically any desired form of surface having precise contours can be printed with very exact metering of the quantity of paste to be applied. As opposed to usual methods, the proposed method is extremely economical since masking, as is required, for example, for screen printing or with the etching technique, is not required. Because accurate metering of the paste to be applied is possible considerable costs can be saved due to the saving in expensive precious metals, especially due to the saving of platinum in the production of metering probes.

Advantageous further developments and im- provements of the method set forth in the main claim and particularly advantageous uses of the method in accordance with the invention are made possible bythe measures set forth in the sub claims.

An embodiment of the invention is illustrated diagrammatically in the drawing with the aid of a particularly advantageous application and is ex pained in detail in the following description. The Figure shows the printing of the external electrode of a Lamba-probe.

The Figure shows in a diagrammatic representation the printing of the external electrode 16 of a Lambda-probe by means of a rotary movement of a printing roller 21 which consists of silicone rubber.

The printing roller 21 receivesthe paste to be applied predetermined as regards form and quantity from an application roller 22 forming the printing block and transfers the paste corresponding to the grid-like paste pattern of its outer surface to a Lambda-probe 15 an an external electrode 16. The Lambda-probe 15 forms an electro-mechanical measuring sensor 15 for determining the oxygen content in gases, particularly in exhaust gases from combustion engines.

During the printing procedure, it is rotatably mounted as indicated by the arrow 23. Subsequently, a further external conductor strip is applied to the grid-like external electrode 16. Either one of the two application operations can also take place in accordance with another application method when this is required for a reason which need not be discussed in detail here, for example because other manufacturing devices which are provided still need to be used.

The two stated printing operations are independent of one another and can each be carried out in the advantageous way and manner in accordance with the invention.

The described method in accordance with the invention offers considerable manufacturing improvements, the advantageous applications are made possible by accurately arranged and dimensioned layer thickness-conductive area which can be produced both as an area pattern and as conductor strips or printed circuits. Due to the deformability of the printing die curved surfaces can be coated with the conductive paste without any distortion of the print since the deformation of the silicone rubber roller is taken into account during the formation of the block. The pastes for printing the external electrode 16 or an external conductor strip can have the same or similar compositions as are described, for example, in the specifications referred to above.

Moreover, platinum and zirconium dioxide, for example, in the volume ratio of 60:40 form the conductor strips proper after sintering of the printed pattern whilst organic additions to the paste which improve the printing ability practically completely volatilise during sintering within the temperature range of 10000C and above

Claims

1. A method of producing electrically conductive areas such as conductive surface patterns, conductor strips, printed circuits or the like, wherein an electrically conductive paste used in a printing process is applied by means of an elastically deformable die to predetermined areas of a preferably uneven carrier, characterised in that, the die is formed as a printing roller (21) and performs a- rotary movement for applying interconnected or endless patterns (16).

2. A method according to claim 1, characterised in that, the die (211 takes up the conductive paste after the fashion of an ink printing process from an application roller (22) forming a block in the predetermined quantity and geometrical formation and transfers it to the part (15, 32, 34) to be printed.

3. A method according to claim 1 or 2, characte rised in that, the printing roller (21) consists of silicone rubber.

4. A method according to one of claims 1 to 3, characterised in that, the depth of etching of the application roller (22) is greater than 20 ,t~m, prefer ably greater than 40 zm.

5. A method according to one of the preceding claims, characterised by the application for the production of a terminal conductor strip of an electro-chemical metering sensor (15) for determining the oxygen content in gases, particularly in exhaust gases from combustion engines (lambda probe) (15).

6. A method of producing electrically conductive areas substantially as herein described with reference to the accompanying drawing.

6. A method according to one of claims 1 to 4, characterised by the application for the production of an external electrode (16) of a Lambda-probe (15).