DE102011051411A1 - A prepreg, a method for producing a prepreg, a method for producing a printed circuit board element and printed circuit board element - Google Patents

Abstract

The present invention relates to a prepreg (21) for use in the manufacture of printed circuit boards comprising one or more spacer elements (22, 24).

Description

Technical area

The present invention relates to a prepreg for use in the manufacture of printed circuit board elements, a process for producing such a prepreg, and a process for producing a printed circuit board element and a printed circuit board element.

Description of the Prior Art

From the prior art printed circuit boards with inner layers are known, such as from EP 1 639 869 B1 and the DE 20 2007 003 815 U1 ,

Prepregs for use in the manufacture of printed circuit boards or printed circuit board elements are also known, for example from US 2010/0044087 A1 ,

Summary of the invention

According to the invention, a prepreg with the features of claim 1, a method for producing a prepreg with the features of claim 5, a method for producing a printed circuit board element with the feature of claim 7 and a printed circuit board element having the features of claim 9 are proposed.

The idea according to the invention is no longer to design prepregs as a homogeneous material web, as is generally customary, but to provide at least one spacer element in the prepreg.

This makes it no longer possible to use the compression pressure as a pressing measure when pressing the printed circuit board multilayer structure, but to carry out a distance-controlled pressing. In other words, this means that pressing with a prepreg according to the invention is carried out until the entire prepreg layer has been compressed to the thickness of the spacer.

The prepreg layer according to the invention may comprise a modification of at least two spacer elements of different thickness.

The spacer elements can be designed according to the invention, for example as so-called "resin rivets", d. H. they may be sections in the prepreg layer consisting of pre-compressed resin. The resin rivets may be made of the same material as the remaining prepreg layer (or of the material from which the prepreg layer will be made after compression).

The resin rivets can be formed separately and introduced into defined areas of the prepreg layer.

Alternatively, the spacer rivets may be formed by selectively pre-pressing defined portions of the prepreg layer from the material of the prepreg layer. After pre-pressing, the resin rivets produced in this way can be cured.

One possible application of the prepreg layer according to the invention is in the production of printed circuit board elements. By using a prepreg according to the invention having at least one spacer element, a desired distance between the inner layer region and a cover layer can be set according to the thickness of the spacer element. This ensures the formation of vias desired defined length for Ankontaktierung the at least one inner layer region.

The invention can be used, for example, in printed circuit board elements which have at least two inner layer regions of different thickness and in which the goal is to contact these inner layers with vias of the same length, these vias being intended to be flush with a covering layer covering the inner layers.

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination indicated, but also in other combinations or in isolation, without departing from the scope of the present invention.

The invention is illustrated by way of example with reference to embodiments in the drawing is highly schematic and not drawn to scale and will be described below in detail with reference to the drawings.

Brief description of the drawing

1 shows a side sectional view of an inventive prepreg with spacer element.

2 shows a lateral sectional view of a printed circuit board element produced using a prepreg according to the invention.

Detailed description

1 shows a section of a prepreg according to the invention 21 in lateral sectional view. The prepreg 21 comprises a prepreg layer 20 consisting of conventional material known to those skilled in the art which liquefies under pressure and comprises at least one resin component and at least one hardener component. Exemplary is on the US 2010/0044087 A1 directed.

Furthermore, the prepreg comprises 21 a spacer element 24 that in the prepreg layer 20 is trained. In the illustrated section is a spacer element 24 of the prepreg 21 shown, however, may still have more spacer elements.

The spacer element 24 has a thickness d smaller than the thickness of the prepreg layer 20 , When using the prepreg according to the invention 21 can the spacer element 24 thus when compressing or pressing the prepreg layer 20 serve as a "stop", ie when the prepreg layer 20 to a thickness corresponding to the thickness d of the spacer element 24 was pressed together, the pressing process is stopped.

The spacer element 24 may, for example, consist of already precompressed resin. One way of making the spacer element 24 consists according to the invention therein, a defined section 26 the prepreg layer 20 undergo precompression. In the process, the defined section is targeted 26 pressurized and possibly also heated to compress it to a desired thickness d. Subsequently, the portion thus compressed becomes the spacer member 24 hardened.

The prepreg 21 can - as already mentioned - have several such spacer elements. The spacer elements may also have different thicknesses. Thus, different thicknesses of a printed circuit board multilayer structure can be compensated or represented in a defined manner.

2 shows a side sectional view of a multilayer structure of a printed circuit board element 10 , The circuit board element 10 comprises a double-sided electrically conductive base layer 12 , which has recesses, in the inner layer areas 16.1 . 16.2 are introduced. While the base layer 12 has a uniform thickness, have the inner layers 16.1 . 16.2 different thicknesses.

The inner layers 16.1 . 16.2 are flush with an upper level of the base layer 12 arranged and close together with this to a prepreg deck layer 20 ' and 13 at. Through the prepreg cover layer 20 ' and 13 there are several vias 18 for contacting the inner layers 16.1 . 16.2 intended. The vias have the same dimensions and in particular the same length (which corresponds to the thickness d of the spacer elements plus the thickness of the cover layer).

The inner layers 16.1 . 16.2 are in a resin layer 20 ' embedded. The resin layer 20 ' has different thicknesses and the same through the different thicknesses of the electrically conductive layer 12 and the inner layers 16.1 . 16.2 resulting level differences.

The construction described is achieved according to the invention in a simple manner by using a prepreg according to the invention 21 with spacer elements 22 . 24 achieved. The different distances to the opposite copper layer 14 arise during the pressing process in that sets a fixed distance through the spacers and the distances to the copper layer 14 arise as resultant.

The multi-layer construction is then subjected to a compressive pressure to compress and liquefy the prepreg until the spacer thicknesses are achieved. Thereafter, the structure is cured.

In printed circuit board element ( 10 ) with a double-sided electrically conductive base layer ( 12 ) and at least two inner layer regions arranged in recesses of the base layer ( 16.1 . 16.2 ), wherein a first inner layer area ( 16.1 ) has a first thickness and a second inner layer region ( 16.2 ) has a second thickness, the first thickness is greater than the second thickness, the inner layers ( 16.1 . 16.2 ) about vias ( 18 ) in an electrically conductive layer ( 12 ) and the at least one inner layer region ( 16.1 . 16.2 ) covering cover layer ( 13 ), the lengths of the at least two inner layer areas ankontaktierenden vias ( 18 ) are equal and on one level with the top layer ( 13 ), and the at least two inner layer areas ( 16.1 . 16.2 ) with a resin layer ( 21 ) are pressed.

Alternatively, the spacer elements 22 . 24 have different thicknesses (not shown), for example, to produce vias of different length, defined by the different thicknesses of the spacer elements (as described above, thickness of a spacer element plus thickness of the cover layer) with a uniform cover layer.

Of course, there are several ways to prepare a prepreg according to the invention. For example. "Pins" made of compressed resin or other suitable material can also be prefabricated and introduced as spacer elements at defined locations / sections in the prepreg layer.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1639869 B1 [0002]
• DE 202007003815 U1 [0002]
• US 2010/0044087 A1 [0003, 0018]

Claims (10)

Prepreg ( 21 ) for use in the manufacture of printed circuit boards comprising one or more spacer elements ( 22 . 24 ). Prepreg ( 21 ) according to claim 1, of which at least one spacer element ( 22 . 24 ) is formed from already compressed resin. Prepreg ( 21 ) according to claim 2, of which at least one spacer element ( 22 . 24 ) by selectively pre-pressing at least one section ( 26 ) of the prepreg ( 20 ) is formed. Prepreg ( 21 ) according to one of claims 1 to 3, which comprises at least two spacer elements ( 22 . 24 ) of different lengths. Process for producing a prepreg ( 21 ) for use in printed circuit board manufacture, comprising the following steps: providing a prepreg layer ( 20 ), - pre-pressing at least one section ( 26 ) of the prepreg layer ( 20 ) until this section ( 26 ) has a desired thickness (d), - curing the at least one pre-compressed section ( 26 ) for forming as a spacer element ( 22 . 24 ). Method according to claim 5, wherein at least two sections of the prepreg layer ( 20 ) are pre-pressed and cured to two different thicknesses. Method for producing a printed circuit board element ( 10 ) with at least one inner layer region ( 16.1 . 16.2 ), comprising the following steps: - providing a copper foil ( 14 ), - applying a layer structure with at least one base layer ( 12 ) and at least one in this base layer ( 12 ) inserted inner layer area ( 16.1 . 16.2 ), - placing a prepreg layer ( 20 ) with at least one in the prepreg layer ( 20 ) spacer element ( 22 . 24 ), such that the at least one spacer element ( 22 . 24 ) over the at least one inner layer region ( 16.1 . 16.2 ), - placing another copper foil ( 13 ), - compressing the layer arrangement to the prepreg layer to the height of the on the at least one inner layer region ( 16.1 . 16.2 ) is mounted on the spacer element pressed together. Printed circuit board element produced by the method according to claim 7. PCB element ( 10 ) with a double-sided electrically conductive base layer ( 12 ) and at least one in recesses of the base layer ( 12 ) arranged inner layer area ( 16.1 . 16.2 ), wherein in one above the at least one inner layer region ( 16.1 . 16.2 ) lying resin layer ( 20 ' ) at least one spacer element ( 22 . 24 ) whose thickness (d) the distance between the inner layer area ( 16.1 . 16.2 ) and a cover layer ( 13 ) Are defined. PCB element ( 10 ) according to claim 9, further comprising in the top prepreg layer ( 13 . 20 ' ) trained vias ( 18 ) whose length is determined by the thickness (d) of the at least one spacer element ( 22 . 24 ) is defined.

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