DE2656489C3 - Circuit board for a high-frequency circuit arrangement - Google Patents

Description

State of the art

The invention relates to a printed circuit board for a high-frequency circuit arrangement on its upper side equipped with components and provided with conductor tracks on their underside, and on both Printed circuit board sides has large conductive surfaces as surface earth, which are geometrically irregular on several distributed points by means of holes, the inner walls of which are metal-coated, through the circuit board are conductively connected to one another through them.

Such a circuit board is known from FR-PS 13 26 549.

The two flat grounds on both sides of the circuit boards serve as low-resistance ground connections, z. B. with the metallic housing. The points of the circuit arrangement to be earthed, i.e. the relevant connecting wires can in this case a double-sided laminated circuit board with both Surface earths are conductively connected.

There are small holes in the circuit board to connect the two surface grounds themselves provided, which are metal-coated on the inside, i.e. plated through.

In places where the surface earth is disturbing, for example because of undesired capacities with certain Components would occur, the lamination of the top side carrying the components is simply etched away. On the underside, the lamination is etched away where the conductor tracks from each other and from the surface earth must be insulated. The connection of the two surface grounds results in the parallel connection two resistors that reduce the total resistance of the ground line.

To connect two surface earths located on the top and bottom of a circuit board other possibilities known as the plated-through holes. For example, from DE-OS 22 16 333 a printed circuit board with double-sided surface earths known, which is used to connect the two surface earths with Has conductor material coated edge surfaces.

For some applications, however, such bilateral ground connections are still closed high resistance, e.g. B. at frequencies above 100 MHz, i.e. H. at Frequencies at which the skin effect is effective, especially if it is to be ensured that for certain functional units have a defined, stable ground potential

This is very important for amplifiers with strong negative feedback, e.g. B. in amplifiers with bridge transformers.

task

It is the object of the invention to design a circuit board of the type mentioned so that it can be used for High-frequency circuit arrangements in which the skin effect is effective, is suitable, so that for certain functional elements a constant ground potential is achieved.

solution

The object is achieved with the means specified in claim 1. A further development results from the subclaim.

description

An embodiment of the invention will now be explained in more detail with reference to the drawings

F i %. 1 is a plan view of part of the top of a circuit board;

F i g. 2 shows an enlarged section along the line 1-1 from FIG. 1.

The circuit board 2 from FIG. 1, which is copper-clad on both sides, is one with the frame 3 metallic housing connected that is earthed.

Either both sides of the circuit board are conductive with the frame 3 independently of one another connected, or it is only one side with the frame and the other side with this side by one Edge lamination of the circuit board conductively connected.

One of the sides or both sides of the circuit board 2 are connected to components 4 of an RF circuit arrangement equipped. Consider a circuit arrangement that is, for example, in the case of a negative feedback broadband amplifier (60 MHz) can be used.

It is important to achieve an optimal negative feedback loop a defined, constant ground potential is necessary for various functional units. this is achieved by means of a suitable arrangement of plated-through holes 5, as follows is explained, form a low-resistance ground connection.

In the example shown, a ground connection runs by means of the holes 5 along a line 1 - 1 to the frame 3 of the housing. Another ground connection by means of the holes 5 runs perpendicular thereto, along a line 8-8. This is for different functional units of the assemblies located on the circuit board a constant ground potential is guaranteed in each case.

Independent of these boundary lines, there are also suitable places within a functional unit the circuit arrangement arranged further individual plated-through holes, if there is a special one constant ground potential is necessary. This kind of "point-wise" connection of the two opposite ones However, as already mentioned, conductive surfaces are known.

Fig. 2 shows a section along the line 1-1 from Fig. 1. You can see the holes 5 from the top

6 reach to the bottom 7 of the circuit board. In the following, the description is based on circular holes limited, although the same effect also occurs through holes with a different cross-sectional shape such as through the The thick lines indicated are both the top and bottom of the panels, as well as the inner walls of the holes coated with metal, preferably copper. The holes have a diameter of about 5 mm. This creates a large-area, i.e. low-level connection between the two surface grounds and thus a low-resistance earth connection to the housing wall along the line 1-1 from FIG. 1 created.

It should be emphasized that the linear arrangements of plated through within the conductive surfaces lying holes 5 not always a ground connection

to the housing frame as in FIG. 1 must represent. in the general are those that are arranged one after the other Holes provided wherever an increased linear concentration of mass is necessary

So z. B. also with a functional unit located within the circuit board in whole or in part be surrounded by such holes in a linear arrangement. In another, not shown, The housing frame can be used in a sufficiently dense arrangement of the plated through Holes along the edge of the circuit board to be replaced. The resulting concentration of The mass at the edge of the circuit board can be increased even further by means of edge lamination.

1 sheet of drawings

Claims (2)

Patent claims: 1. Circuit board for a high-frequency circuit arrangement, which are equipped with components on their upper side and conductors on their underside is provided, and which has large conductive surfaces as surface earth on both sides of the circuit board, the at several geometrically irregularly distributed points by means of holes, the inner walls of which are metal-coated are conductively connected to one another through the printed circuit board, thereby characterized that within the conductive surfaces (6, 7) additionally at least one line (8-8, 1-1) of regularly arranged holes (5) with metal-coated inner walls is present, the a group of components (4) that belong together spatially and functionally on at least one their sides limited and that the regularly arranged holes (5) larger than diameter which have irregularly spaced holes. 2. Circuit board according to claim 1, characterized in that the conductive surfaces (6,7) at least are continuously connected to one another on an edge surface of the circuit board (2).