DE19618254A1 - Multi-layer circuit manufacturing method - Google Patents

Abstract

The manufacturing method has a number of internal layers stacked together with intermediate prepreg layers before uniting the stack by applying upper and lower Cu foil outer layers, to provide a layered packet. The inner layers are provided with alignment marks at defined reference points, with initial positioning of the first inner layer via these markings and positioning of the successive layers by alignment of the markings with the first layer.

Description

The present invention relates to a method ren for the production of a multilayer according to the Oberbe handle of claim 1.

Printed circuit boards form the basis for electronic Circuits like those in all areas of technology be used. The trend is towards so-called Multilayer (multilayer circuit) boards with steady increasing number of layers, which is a compact, space-saving Allow construction. By using multilayer Circuit boards will increase the integration density enough. Multiple layers and fine structures are ahead setting for miniaturization in electronics.

While multilayer production itself is largely automated nowadays, the so-called registration process (ie the steps of positioning and fixing the individual layers before the actual pressing process) is based on costly and time-consuming manual process steps. According to the state of the art, multilayer production runs as follows:
First, the inner layer individual layers are manufactured. This is followed by the steps of measuring and punching the openings to align the individual layers. In a third process step, the intermediate layer adhesive layers known under the term PREPREG are applied. To align the individual layers, these are finally aligned with the aid of so-called fixing rods over the previously punched openings. The conclusion of the multilayer production then forms the pressing, whereby the plastic is heated to about 200 degrees and the individual layers bond inseparably.

At this point it should also be noted that for the proper functioning of a multilayer precise positioning of the inner layers by entschei meaning.

A problem point of the known or usual Manufacturing technology is the attainable accuracy, through the existing play between the punched Breakthroughs and the locating pins, as well as through which he Reachable alignment accuracy when punching itself influenced and thus possibly impaired. Furthermore, there is a known problem in the not insignificant risk of confusion of the individual Inner layers, since these are packaged manually. On decisive disadvantage of the procedure common today can also be seen in the fact that the necessary Fer time due to the manual work steps Multilayer manufacturing severely affected.

The problem underlying the present invention be is a process for automated re registration and fixation of the individual layers of a To develop multilayers in which the aforementioned Pro blemishes are eliminated.  

The aforementioned task is accomplished by the in Patentan Proceed 1 specified solution.

In other words than used in the claim The essence of the present invention is a automatically working system for fully automatic Registration and fixation of inner layers into one Propose press core that no mechanical re registration required. The alignment takes place from finally on the basis of exposed and then etched reference points respectively Registration marks. The system works on a continuous basis with the options that the sorted inner layers and the required prepreg positions manually or automatically (for example with the help of suitable computer supported handling devices) are supplied. The one individual layers (inner layer or prepreg layer) are from System infeed transported to an alignment table and mechanically via a central axis in the X and Y axes prepared. Then the inner layers additionally fine using an image processing system aligned. The first inner layer of a Multi layers serves as clear and reproducible Reference for all the following inner layers in the multilayer. With the help of a suitable transport system in a workstation (connection / stacking station) pla graced inner layer is there by means of vacuum on their Work surface kept. This is followed by a Prepreglage introduced and on the previously working stored in the area of the inner layer and selectively fixed. Already during this process, overlapping - already the next inner layer over yours Reference point optically aligned, from the transport system taken over and on the already existing stack of Inner layers and prepreg layers in the work area posi placed exactly.  

The inner layers and separating layers are given in this way if automatic - successively the connecting station fed and here each with the already stacked Layers connected. Finally, the outer locations in Shape of copper foils applied, so that ultimately A multilayer is created, the inner layers of which alone arranged due to optical alignment and assignment are. This stack of multilayer layers is then in a suitable press station for the finished multilayer pressed.

A particular advantage of the method according to the invention is that the inner layers on both sides brought or etched reference points po can be sitioned. About suitable image processing Both sides of the inner layers are removed guards so that a clear alignment is guaranteed is.

Special configurations of those outlined above benen invention are the subject of the dependent claims. In this regard, it should be noted in particular that due to the possibility of the individual inner layers automated or computer-assisted handle every possibility of confusion a priori is avoided.

The invention is described below with reference to the schematic radar position explained again in more detail.

In this schematic representation are from left to right the following features or elements are shown:

• - The outer layers in the form of copper foils, and as the upper A side and as the lower B side for Apply on the out
• - Inner layers on the one hand and
• - PREPREG layers on the other hand

stacked multilayer stack.

A first inner layer is made using a suitable transfer system a so-called (X-Y-ϕ) alignment relationship wise straightening table fed. For this first inner layer is over two previously applied, especially etched Reference points set a clear reference position. After removal via a so-called transport shuttle and the shelf on a work table (conn stacking station) without any loss of position is fixed with the help of a suction system. On finally - also automatically - a prepreg location fed. The next inner layer will also be about the optical method according to the reference situation or according to the conjugate reference points aligned and exactly to the previous inner layer positioned.

The individual layers (inner / prepreg layers) are like this Layer by layer via a temporary connection system according to the types of joining, gluing, welding or riveting fi xiert.

The main features of the novel process are ultimately an optically exact, image ver work-protected alignment of the individual interior lay on the (X-Y-ϕ) alignment table and on the other a new, final fixation of the single layer positions before pressing, after their stable transfer to the work table, d. H. to the connection / stacking station.  

As already mentioned, the position accuracy of the Inner layers additionally laid out on the second page etched registration marks are monitored.

The advantage of the new process is particularly in it to see that as a result of the purely optical registration without any mechanical registration openings highest accuracy with one registration or reproducibility of +/- 10 µm ge can be guaranteed. By performance In image processing, the positions can be correct Order to be checked. By the shuttle-guided There is no transition from positioning to fixing in addition, the manual packaging process before actual pressing. The design of the system as Continuous plant increases the throughput overall over conventional manufacturing technology Lich.

There are also considerable savings in Machine area. Since no mechanical processing (no drilling or punching) of the inner layers necessary there are other machines for multilayer production not necessary for this process step; the problem Matters of inaccuracy due to tolerances are a priori not given.

The flexibility of the pressing process on different Multilayer formats are increased significantly. So is with conceivable for example, two multilayers different Press geometries in one tool. Because the one individual layers through the temporary fixing system positio Staying nated is not an additional registration system required in the pressing tools and intermediate plates.  

With reference to the schematic representation, the following should also be noted:
If inner layers and prepreg layers in the work station (connection / stacking station) are merged in their specified allocation and arrangement and connected to one another, a so-called press core (inner layer core) is available as an intermediate product.

On this press core are - in the form of one Copper foil and after applying a prepreg layer - an upper outer layer (A-side) and a lower one Apply outer layer (B-side) and their function to be provided with a conductor structure accordingly. The the upper outer layer may already be in the Connection / stacking station are placed; in general However, it is my opinion that both outer layers in one downstream of the connection / stacking station station applied and processed.

Ultimately, one of the inner and prepreg layers as well as two outer layers (Cu foils) Multilayer available, however the locations are still are not connected to one another over a large area. This Multilayer package is now - and without additional Posi tionations - fed to a suitable press, in then the layer ensemble, d. H. the press cores with their outer layers between the top plate of the press a floor press and the sub plate of the pressing tool (compare Dar position), pressed together with the required pressure becomes. The press is then a finished multilayer in taken from compact shape and complex composition. If necessary - compare depicted depictions lung - also several layer ensembles with interposition  an intermediate plate or an intermediate be packaged and pressed together.

Claims (4)

1. A method for producing a multilayer (multi-layer circuit) consisting of a plurality of inner layers and prepreg layers, the inner layers being aligned in relation to each other in an exact manner before a given assignment and being stacked one above the other with the prepreg layers, and this stack (inner layer core) underneath Addition of an upper and lower outer layer (copper foil) are firmly connected to each other to form a layer package,
characterized,
that reference points (registration marks) which are clearly defined relative to one another are applied to the inner layers together with the line structure, and
that the following procedural steps are then provided:

• a) a first inner layer is positioned exactly according to its reference points on an alignment / straightening table and then locked, and fed to a work station (connection / stacking station);
• b) the other inner layers are aligned according to the predefined assignment, in each case equally on the straightening table and are fed to the work station in a stable manner, in such a way that
• - That the inner layers are aligned exclusively on the basis of their reference point in exact assignment to the first inner layer, and
• - That the successively fed inner and prepreg layers are each immovably connected with the Ar beitsstation supplied inner and pre preglagen, so that a one-piece press core (inner press core) is present, and
• c) then further prepreg layers, as well as the outer layers (A / B sides) are placed on the press core and, according to their intended function, opened with conductor structures.

2. The method according to claim 1, characterized, that the upper outer layer (A-side) in the working station placed on the press core and fixed becomes. 3. The method according to claim 2, characterized, that the lower outer layer (B side) on the around the upper outer layer (A-side) added press core on ge places and is fixed. 4. The method according to any one of claims 1 to 3, characterized, that the inner layers and the prepreg layers the direction table using an automated, for example  as a computer-controlled feeder be fed.