Title of Invention

"METHOD FOR THE PRODUCTION OF CIRCUIT BOARDS AND/OR CORRESPONDING CONSTRUCTS"

Abstract Disclosed is a simplified, inexpensive method for producing printed circuit boards and/or corresponding constructs comprising points where through-connections are created. Such a method dispenses with the need for a very complex brushing process while using exclusively low-cost lacquer variants. More-over, the inventive method allows additional strip conductors or appropriate layers to be guided even directly across the through-connections rather than just to said through-connections.
Full Text Description
Method for the production of circuit boards and/or corresponding constructs
The invention relates to a method for the production of circuit boards and/or corresponding constructs according to the preamble of claim 1.
In the production of circuit boards and/or corresponding constructs comprising points at which through-connections are created, the problem exists that a layer of insulating lacquer applied to the strip conductor image does not guarantee secure insulation, especially on the edges of the openings of the through-bores of the through-connections.
The reason for this is firstly that the insulating lacquer runs into the through-bores and peels off, as it were, on the edges of the openings of the through-bores. As a result of this, the thickness of the layer of insulating lacquer becomes at least very thin on the edges concerned. Secondly, the layer of insulating lacquer is not 100% non-porous, so there are small and very small holes which cause the electrical resistance relative to the electrically conductive layer arranged thereunder, which in this case forms the electric through-connection, to become less than infinite.
This has a detrimental impact, for example, when a further electrically conductive layer, whether in the form of a further strip conductor, for example, or in the form of a larger area, for example, is arranged above the through-connection. The advantage that is achieved here is that the surface of the circuit board or of a corresponding construct

is used substantially more intensively. That is, even those areas are used which are otherwise left free so as to prevent short-circuits to the through-connections.
The short-circuits here are not necessarily extremely low-impedance short-circuits in each case. Short-circuits are also present when the insulating resistance is less than infinite, so there is the possibility that creeping currents will flow.
A method for the production of circuit boards is known from document WO 02/078411 A, said circuit boards having points at which through-connections are created, at least in the proximity of which strip connectors or an electrically conductive layer is also provided. Here the through-bores of the through-connections have diameters which are above a size range of 20 micrometers. Additionally a method step is lacking in which the through-connecting takes place in that an electrically conductive general layer is formed before the through-holes are filled with a standard medium.
A method for the production of multilayer circuit boards is known from document US-A-5 758 413 with a diameter of 120 micrometers and less only for the through-connections.
The object of the invention is to specify a simple and low-cost method for the production of circuit boards and/or corresponding constructs comprising points at which through-connections are created and, at least in the proximity of said points, strip conductors or similar are also provided.
This object is achieved according to the invention in a method which comprises the method steps specified in claim 1.

This method has the advantage that it is easy to control and that it nonetheless ensures that no short circuits are produced between the through-connections and the strip conductors or correspondingly similar arranged at least in the proximity of the through-connections.
The method is easy to control and is low in cost because, in particular, a very complex brushing method step, in which the surface of the circuit board or of a corresponding construct is brushed, is cut out. The method is also simple and low in cost because standard media can be used throughout and consequently it is not necessary to use special media at least in some method steps. The method also guarantees short-circuit protection above the through-connections in particular because in practice three insulation layers are applied above the through-connections. Thus, firstly, a relatively thick general insulation layer is created overall and secondly, with three insulation layers, the probability that open pores in each insulation layer will coincide precisely with one another
three times is practically ruled out.
Advantageous embodiments of the invention are the subject matter of subclaims.
According to these, identical standard media can be used in several method steps in which previously special media were required at least in part.
A further advantage is that the standard media can be low-cost media.
A further advantage is that the strip conductors or such like arranged above the through-connections can be realized using low-cost carbon.
Finally, it is advantageous that the separation of individual circuit boards or corresponding constructs continues to be carried out by means of simple milling from a larger structure.
An exemplary embodiment of the invention is described in detail below with the aid of a drawing.
In the single drawing, a comparison is made between on the left-hand side the sequences of an existing method and on the right-hand side the sequences of the method according to the invention for the production of circuit boards and/or corresponding constructs comprising points at which through-connections in the 20 pm size range are created, in the proximity of which points or above which points further strip conductors or corresponding are arranged.
The existing method, based on the example of the production of a circuit board, comprises the following method steps:
1. Drilling of through-bores for the through-connections;
2. Production of through-connections;
3. Filling of bores of the through-connections with an etch-
resistant plugging paste (= a special medium);
4. Brushing of the surfaces so that it is possible
subsequently to produce the etched image (strip-conductor
image) on plane and clean surfaces;
5. Etching of the circuit board, by which is meant all
measures which are necessary for a finished strip conductor
image to be produced;
6. Lacquering of the surfaces with a stop lacquer so that a
first lacquer layer is applied which covers at least
slightly the electrically conductive surfaces and surface
elements (strip conductors) as well as the surfaces of the
through-connections and also that the interspaces between
the electrically conductive surface elements are at least
partially filled;
7. Application of the actual insulating lacquer (ISO lacquer)
so that overall firstly a plane surface is again provided
and secondly a secure insulation exists in relation to the
electrically conductive surfaces and surface elements
arranged thereunder/ which is why it is then possible that
further electrically conductive surfaces and surface
elements can be provided on these surfaces, except above
the through-connections, because ultimately as a result of
the absence of a filling of the through-connections no
plane surface is produced there.* Here, the lacquer runs at
least somewhat into the through-connection each time;
8. Application of further electrically conductive surfaces and
surface elements (for example, carbon strip conductors
(I)), whereby, for reasons of avoiding short circuits, a
relatively large gap is maintained, especially on the edges
(2) of the through-bores of the through connections on
which only a particularly thin insulation forms;
9. Testing of the circuit board, and
10. Separation of the individual circuit board by milling of the circuit board from a group of circuit boards whereby, for reasons of efficiency, one circuit board is generally produced.
By comparison, the inventive method comprises, taking the production of a circuit board as an example, the following method steps:
1. Drilling of through-bores for the through-connections;
2. Production of through-connections;
3. Etching of the circuit board, by which is meant all
measures which are necessary for a finished strip conductor
image to be produced;
4. Filling of the bores of the through-connections with a
standard plugging paste (= standard medium in the form of a
low-cost lacquer variant which achieves a saving effect and
simplifies the method flow), it being possible at this
point for complex and expensive brushing of the surfaces to
be dispensed with (together with the omission of complex
and expensive brushing of the surfaces prior to etching, as
was otherwise required in the case of the previous process
flow, this produces a further substantial saving effect and
a further simplification of the method flow);
5. Lacquering of the surfaces with a stop lacquer so that a
first lacquer layer is applied which covers at least
slightly the electrically conductive surfaces and surface
elements (strip conductors) and also fills the interspaces
between the electrically conductive surface elements at
least in part;
6. Application of the actual insulating lacquer (ISO lacquer)
so that overall firstly a plane surface is again provided
and secondly a secure insulation exists in relation to the
electrically conductive surfaces and surface elements
arranged thereunder, which is why it is then possible that
further electrically conductive surfaces and surface elements can be provided on these surfaces, even directly above the through-connections;
7. Application of further electrically conductive surfaces and surface elements (for example, carbon strip conductors (3)}, it now also being possible for these electrically conductive surfaces and surface elements to be guided at least to the through-connections and even directly across them;
8. Testing of the circuit board, and
9. Separation of the individual circuit board by milling of the circuit board from a group of circuit boards, whereby, for reasons of efficiency, one circuit board is generally produced.
The standard plugging paste, the stop lacquer and the insulating lacquer can all be identical, i.e. consist of just a single low-cost lacquer variant.
The application of the lacquer layers can be accomplished by means of the screen-printing method which is known in the art and is easy to implement.
According to the present invention a method for the production of circuit boards and/or corresponding constructs comprises points at which through-connections in the 20 um size range are created and, at least in the proximity of said points, strip conductors or an
electrically conductive layer are also provided, characterized by
the following key method steps:
- drilling of through-bores in the 20 um size range for the
subsequent production of through-connections;

- through-connecting, whereby an electrically conductive general layer is built up;
- etching of the strip conductor image into the electrically conductive general layer;
- filing of the bores of the through-connections with a standard medium;
- lacquering of the surfaces on which through-connections are present and, at least in the proximity of which, strip conductors are later provided;
- applying of insulating lacquer (ISO lacquer), which is a standard medium, to the surfaces of the circuit board and/or of the corresponding construct;
- producing of strip conductors arranged above the though connections;
- testing of the circuit board and/or of the corresponding construct;
- separating of the individual circuit board and/or of the corresponding construct.





We claim:
1. A method for the production of circuit boards and/or
corresponding constructs comprising points at which
through-connections in the 20 um size range are created
and, at least in the proximity of said points, strip
conductors or an electrically conductive layer are also
provided, characterized by the following key method
steps:
- drilling of through-bores in the 20 um size range for the subsequent production of through-connections;
- through-connecting, whereby an electrically conductive general layer is built up;
- etching of the strip conductor image into the electrically conductive general layer;
- filing of the bores of the through-connections with a standard medium;
- lacquering of the surfaces on which through-connections are present and, at least in the proximity of which, strip conductors are later provided;
- applying of insulating lacquer (ISO lacquer), which is a standard medium, to the surfaces of the circuit board and/or of the corresponding construct;
- producing of strip conductors arranged above the though connections;
- testing of the circuit board and/or of the corresponding construct;
- separating of the individual circuit board and/or of the corresponding construct.
2. The method as claimed in claim 1, wherein the standard
medium is identical in each of the different method
steps.

3. The method as claimed in claim 1 or claim 2, wherein the standard medium in the different method steps is in each case a low-cost lacquer variant.
4. The method as claimed in any one of the preceding claims wherein at least the strip conductors arranged above the through-connections are realized with carbon (3).
5. The method as claimed in any one of the preceding claims,-wherein the separation of the individual circuit boards and/or of the corresponding constructs is accomplished by means of a milling process.
6. A method for the production of circuit boards and/or corresponding construct substantially as hereinbefore described with reference to the accompanying drawings.

Documents:

5713-DELNP-2006-Abstract-(11-09-2009).pdf

5713-delnp-2006-abstract.pdf

5713-DELNP-2006-Claims-(11-09-2009).pdf

5713-delnp-2006-claims.pdf

5713-DELNP-2006-Correspondence-Others-(11-04-2011).pdf

5713-DELNP-2006-Correspondence-Others-(11-09-2009).pdf

5713-delnp-2006-correspondence-others-1.pdf

5713-delnp-2006-correspondence-others.pdf

5713-DELNP-2006-Description (Complete)-(11-09-2009).pdf

5713-delnp-2006-description (complete).pdf

5713-DELNP-2006-Drawings-(11-09-2009).pdf

5713-delnp-2006-drawings.pdf

5713-DELNP-2006-Form-1-(11-09-2009).pdf

5713-delnp-2006-form-1.pdf

5713-delnp-2006-form-13.pdf

5713-delnp-2006-form-18.pdf

5713-DELNP-2006-Form-2-(11-09-2009).pdf

5713-delnp-2006-form-2.pdf

5713-DELNP-2006-Form-26-(11-09-2009).pdf

5713-delnp-2006-form-26.pdf

5713-DELNP-2006-Form-3-(11-09-2009).pdf

5713-delnp-2006-form-3.pdf

5713-delnp-2006-form-5.pdf

5713-DELNP-2006-GPA-(11-04-2011).pdf

5713-delnp-2006-pct-220.pdf

5713-delnp-2006-pct-237.pdf

5713-delnp-2006-pct-304.pdf

5713-delnp-2006-pct-409.pdf

5713-delnp-2006-pct-416.pdf

5713-delnp-2006-pct-search report.pdf

5713-DELNP-2006-Petition-137-(11-09-2009).pdf


Patent Number 239981
Indian Patent Application Number 5713/DELNP/2006
PG Journal Number 17/2010
Publication Date 23-Apr-2010
Grant Date 19-Apr-2010
Date of Filing 29-Sep-2006
Name of Patentee SIEMENS AKTIENGESELLSCHAFT
Applicant Address WITTELSBACHERPLATZ 2,80333 MUNCHEN,GERMANY.
Inventors:
# Inventor's Name Inventor's Address
1 BUSCH Georg FELDMARK 5,48683 AHAUS,GERMANY
PCT International Classification Number H05K 1/11
PCT International Application Number PCT/EP2005/050919
PCT International Filing date 2005-03-02
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 102004021062.4 2004-04-29 Germany