GB2163007A

GB2163007A - Sheet with printed conductors on both sides and method of forming interconnections between the conductors

Info

Publication number: GB2163007A
Application number: GB08504311A
Authority: GB
Inventors: Gunter Warnecke; Siegfried Laborge
Original assignee: Krone GmbH
Current assignee: ADC GmbH
Priority date: 1984-08-08
Filing date: 1985-02-20
Publication date: 1986-02-12
Also published as: GB2163907A; JPS6148997A; GB8519675D0; GB8504311D0; DE3429236A1

Abstract

The sheet (1) of non-conductive material, preferably of plastics, is provided with openings (4) at predetermined locations, said openings being filled with the material of the conductors (2, 3) and constituting electrical connections (5) between an upper and a lower conductor. It is preferred that the conductors are applied onto both faces of the sheet by a screen printing process, in which prior to the printing operation openings are formed in the sheet into which during the screen printing step conductor material is pressed from both sides until it is mutually firmly joined. <IMAGE>

Description

SPECIFICATION Sheetwith double face printed conductors Today, sheets with printed electrical conductors or wiring, especially sheets of plastics material, may be employed in a variety of applications such as in electric control systems, in telecommunication apparatus etc. One of the features of such sheets that play a decisive part in the greatvariety of possible applications resides in the extremely low manufacturing costs for both simple and complex circuits; these costs amountto but a few pennies per sheet. However, some expenditure is required in the manufacture of plastics sheets with double face printed conductors, e.g. for use in pushbutton dialling blocks when the printed conductors on one face function as static shielding network and the switching functions are performed by the conductors on the other sheet face.

So far, the sheet has been folded about 1800 in order to enable the conductors used for shielding purposes and also the conductors performing the switching functionsto be connected in a simple and inexpensive waytofurther parts ofthecircuit,forinstancethrough a connecting block having push contacts on one side thereof; such folding, however, requires a special configuration ofthe sheet end and also a high- precision folding operation.

It is the object ofthe present invention to provide a sheet with double face printed conductors, said sheet permitting in a simplified mannerthe connection to a connecting block having push contacts on one side thereof. Furthermore, an especially simple method of making such a sheet is to be provided.

In accordance with the invention the sheet with double face printed conductors is characterised in that openings are formed at predetermined locations in the sheet, said openings being filled with the material of the conductors and constituting electrical connections between an upper and a lower conductor.

The method of making such a sheet in accordance with the invention is characterised in that prior to printing ofthe conductors, openings are formed in the sheet into which during the screen printing step conductor material isurgedfromeitherside until a mutual firmjoint is achieved.

Furthersuitable configurations of the invention constitutethe subject matter ofthe subclaims.

A preferred embodiment of the invention will be described in detail with reference to the drawing, in which Fig. 1 is a portion of a plastics sheet provided with doubleface printed wiring, illustrating an electrical joint between the printed conductors; Fig 2 is a perspective sectional view of a plastics sheet; Fig. 3 is the plastics sheet of Fig. 2 after printing of a conductor thereon; Fig. 4 is the plastics sheet of Fig. 3 with conductors printed on both faces and showing two of the electrical joints therebetween.

As will be apparent from Figs. 1 and 4, the upper face of a tear-resistant sheet 1 made of non-conductive plastics has provided thereon an upper conductor 2 2of an electrically conductive material in firmly adhering relationship, appropriately applied by a screen printing process. Inthesamewaythe lower face of the sheet 1 is provided with another conductor 3 of an electrically conductive material in firmly adhering relationship. In orderto establish an electrical ly conductive connection between the two conductors 2 and 3, the sheet 1 is provided with an opening 4 which - as will be apparent from Fig. 2-may have rectangular, round or even slot-like shape. This opening 4 is completely filled with the conductive material of the two conductors 2, 3.This filling 5 of the opening 4 results in an electrically conductive connecting web between the conductors 2, 3.

A suitable method of making a sheet in accordance with the invention will be explained with reference to Figs.2to4.

Fig. 2 shows a portion of a plastics sheet 1 having a circular and a rectangular opening 4a, 4b, respective- ly. Suitably, these openings are punched priorto printing the plastics sheetwith the conductors. The plastics sheet 1 shown in Fig. 3 already bears a printed conductor 2 on its upper face. As will be apparent, during printing a certain portion of the electrically conductive wiring material has entered into the two openings 4a, 4b, and that over the entire cross-section of said openings. In the vicinity of these openings 4a, 4bthe conductor2 has been widened at 6a, 6bto achieve a better adherence of the wiring material in the region of the openings. When the sheet upperface has been printed, the conductor 3 is applied to the sheet lowerface in a further screen printing step, as shown in Fig. 4.During the printing step wiring material penetrates into the openings 4a, 4b from below u ntilituntil into firm engagement with the wiring material already existing in the openings and is joined to the latter along an irregularly extending seam region 7a, 7b.

If both faces of the plastics sheet are printed with the conductors 2, 3 in a single printing operation, the openings 4 will be filled with the wiring material in a completely uniform way as shown in Fig. 1.

Because of the through-contacting according to the present invention ofthe electrical conductor3 on the lowerface ofthe sheet (shielding) with a conductor 2 on the upperface ofthe sheet it is possible to do without the mechanically tedious folding of the entire sheet about 1 809 whereby connection of the conduc torsto a connecting block constituting a sheet connectorwill also be facilitated.

With sheets having a thickness of 0.125 mm made of non-conductive plastics and with openings having a diameter of 0.5 to 0.8 mm, perfect electric devices have been obtained when a conventional conductive carbon lacquerwas employed as wiring material. In ordertoensure reliable inflow ofthewiring material, slot-like openings extending in longitudinal direction of the conductors are preferred. Sheets ofthis type are suitableforthe mostvaried applications in which lead-in and lead-outwires are connected to one side of the sheet only.

Claims

1. A sheet having conductors printed on both faces thereof, characterised in that one or more openings are formed in the sheet, the or each opening being filled with the material of the conductors to provide an electrical connection or connections between the conductors on said faces.

2. A sheet as claimed in claim 1, characterised in that the openings are either round or rectangular holes, orslots extending in the longitudinal direction ofthe conductors.

3. Asheetas claimed in claim 1 claim2, characterised in thatthe conductors are widened in the vicinity ofthe openings.

4. A sheet as claimed in any ofthe claims 1 to 3, characterised inthattheconductormaterial hasflown into the openings from either side.

5. A method of making a sheet as claimed in any of the claims 1 to 4, in which the conductors are applied by screen printing onto both faces of the sheet, characterised in that prior to printing of the conductors, openingsareformed in the sheet into which conductor material is urged during screen printing from eitherside until a mutual firm joint is achieved.

6. A method as claimed in claim 5, characterised in that in a first printing step the openings are filled with the conductor material only partiallyfrom one side, and that in a second printing step the openings are completelyfilledand atthesametimetheconductor material is compacted along an irregularly extending joining region.

7. A sheet having conductors printed on both faces thereof substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

8. A method of making a conductor sheet substantially as herein before described.