According to the present invention there is provided a printed circuit board incorporating surface electrically- conductive plating lines interconnecting electrically conductive pins set into the board at positions where blind holes to receive the pins are provided, the plating extend- ing into and lining the internal side walls of the holes and each pin being constructed to have a mechanical interference fit into the respective hole.

By lining the interior of the blind holes and providing pins which have a mechanical interference fit when pushed into those holes, a positive electrical interconnection between the plating lines and the pins is achieved, together with a secure mounting of the pins into the board. This arrangement is particularly advantageous where the other face of the board (from which the pins project) is required for additional circuit layouts. If the holes extended all the way through the board this would reduce the area over

which those additional circuit layouts on the other face could be provided. Nevertheless there will be instances where there is a need to extend the circuit from one side of the board to the other and for this purpose the plating can additionally extend through through-holes allowing the plating to extend from one surface to the other of the board.

The plating, at least within the blind holes, ideally comprises successive layers of copper, then nickel, then gold plating which provides for a secure coating and good electrical conductivity. Each pin is preferably formed from brass with gold plating.

It is preferred that the end of each pin fitting into a blind hole is knurled or splined, or is split to define compressible projecting parts. This allows for a particu- larly secure grip of the pin into the hole. An enlarged collar can be formed between the two ends of each pin to enable the pin to be gripped readily during the assembly process of inserting the pin into a blind hole.

The invention may be performed in various ways and a preferred embodiment will now be described, by way of example, with reference to the accompanying drawings, in which:- Figure 1 is a section through part of a printed circuit board incorporating pin mountings in accordance with this invention; Figure 2 shows the design of one of the pins mounted into the board of Figure 1;

Figure 3 is a side view of an alternative form of pin for insertion into a board; Figure 4 is an end view of the pin shown in Figure 3; and Figures 5 and 6 illustrate alternative pin shapes for use in the printed circuit board of Figure 1.

A circuit board 1 shown in Figure 1 has a circuit printed thereon formed by a plating process using conven- tional techniques and conventional plating materials giving good electrical conductivity. The plating lines can extend through through-holes 3 to interconnect with further plating lines 4 on the other face of the board 1. A component 5 could, for example, be electrically interconnected to the plating lines 4 in a known manner. Additionally though the board incorporates mounting pins 6 to which electrical components can be attached. In order to locate the pins 6 into the board 1, blind holes 7 are provided (which will not then interfere with the laid down plating lines 4 on the other surface of the board). The plating material of the plating lines 2 extends into the blind holes 7, as indicated at 8, to coat the internal side walls of the holes. In this instance the plating, at least within the holes 7, will comprise successive layers of copper, nickel and gold. A s can be seen from Figure 2 each pin has a splined end 9 which will be an interference fit within the hole 7. Thus when the pin 6 is driven into the hole 7 it will be held tightly in place and additionally will make secure electrical contact with the plating material 8 within the hole 7. A

collar 10 is formed on the pin, largely to enable the pin to be gripped readily during the assembly process.

The alternative form of pin 6A shown in Figures 3 and 4 has a head 11 which is split to define openings 12, thus creating projecting parts 13. When the head 11 of this pin 6A is driven into one of the holes 7, the head can compress to some extent and the projections 13 will grip the interior of the holes 7 firmly and also make good electrical contact with the plating material 8.

The pin shape can be modified in various ways and some possibilities are shown in Figures 5 and 6 for a curved shank 6A or a ball-shaped shank 6B respectively.