PRINTED CIRCUIT BOARD WITH A LEADED COMPONENT AND METHOD OF SECURING THE COMPONENT

Abstract: The invention relates to a printed circuit board provided with at least one component having one or more leads which are secured to contact faces of the printed circuit board. In accordance with the invention, the leads of the component are secured to the printed circuit board via wire clamps soldered onto the surface of the contact faces. The formation of through-holes in the printed circuit board is rendered superfluous by said wire clamps. For the leaded components use can be made of resistors and capacitors, but also of a single electroconductive wire. The invention also provides a method of manufacturing the invented printed circuit board.

Description: PRINTED CIRCUIT BOARD WITH A LEADED COMPONENT AND METHOD OF SECURING THE COMPONENT The invention relates to a printed circuit board provided with at least one component having one or more leads which are secured to contact faces of the printed circuit board. The invention also relates to a method of mounting a component having one or more leads on a printed circuit board, at least one lead of the component being secured to the surface of a contact face of the printed circuit board. Customary printed circuit boards comprise an electrically insulating substrate on which and/or in which a pattern of electroconductive tracks is provided. A number of these tracks terminate at a contact face situated at or on the surface of the printed circuit board. Electric components, such as resistors and capacitors, are secured to such contact faces by means of their terminals. In its most elementary form, such an electric component may consist of a single, electroconductive wire which is connected, for example, to an antenna or to another electric or electronic component which is connected to the printed circuit board via this wire. Resistors and capacitors generally comprise two or more terminals. As regards the above-mentioned electric components, generally two embodiments are distinguished. Such components may take the form of leaded components or of leadless, surface-mountable components (SMD components). When leaded components are provided, the leads are customarily passed through the printed circuit board and subsequently secured to one or more contact faces of the printed circuit board by means of a soldered joint. To place SMD components on the printed circuit board, use is customarily made of a glued joint. Subsequently, the connection faces of the components are electrically connected to the contact faces of the printed circuit board by means of a wave-soldering treatment. The SMD embodiment of components is generally more expensive than the leaded embodiment. Printed circuit boards are frequently provided with a plurality of surface- mountable components and one or a few leaded components. In this case, one or more through-holes are formed in the printed circuit board for the leaded components. In practice, it has been found that positioning and forming the necessary through-holes as well as individually securing the leads by soldering are operations which are very objectionable from the point of view of costs. This applies, in particular, if both leadless and leaded components must be provided on the PCB. It is an object of the invention to provide a printed circuit board having one or more leaded components, in which the above-mentioned problem has been overcome. The invention more particularly aims at providing a printed circuit board having one or more leaded components which are not secured to the printed circuit board via through-holes. The invention also aims at providing a method of mounting one or more leaded components on a printed circuit board. These and other objects of the invention are achieved by a printed circuit board provided with at least one component having one or more leads which are secured to contact faces of the printed circuit board, said printed circuit board in accordance with the invention being characterized in that the leads of the component are secured to the printed circuit board via wire clamps soldered onto the surface of the contact faces. Through-holes for providing the leaded components are rendered superfluous by the use of wire clamps. Said wire clamps are electrically connected to the contact faces via a soldered joint. The leaded components are connected to these wire clamps in a clamping manner. It has been found that a drop of solder at the location where the lead of the component and the wire clamp are secured to each other causes the electric contact between these components to be substantially improved. The invention also relates to a method of securing a component having one or more leads to a printed circuit board, at least one lead of the component being secured to the surface of a contact face of the printed circuit board. In accordance with the invention, this method is characterized in that the lead of the component is secured to the printed circuit board via a wire clamp soldered onto the surface of the contact face. The provision of through-holes in accordance with the known method is dispensed with in the method in accordance with the invention. A preferred embodiment of the method in accordance with the invention is characterized in that the wire clamp is secured to the lead, whereafter said wire clamp is soldered onto the surface of the contact face. This soldering operation has to be carried out manually, preferably, after SMD components, if any, have been provided. Another preferred embodiment of the method in accordance with the invention is characterized in that the wire clamp is soldered onto the surface of the contact face, whereafter the component is secured to the wire clamp via the lead. This embodiment has the advantage that soldering of the wire clamps and of SMD components, if any, can take place simultaneously. Securing the component with the lead or leads to the wire clamp(s) has to be performed manually at a later stage. A further preferred embodiment of the method in accordance with the invention is characterized in that the wire clamp is secured to the contact face of the printed circuit board by means of a component placement machine and a wave soldering process. In comparison with manual placement methods, this method has the advantage that the rate and accuracy with which the wire clamps are placed on the printed circuit board is much greater. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. In the drawings: Fig. 1 shows a printed circuit board in accordance with the invention, Fig. 2 shows a number of embodiments of wire clamps which can be used in the invention. It is noted that, for clarity, the Figures are not drawn to scale. Fig. 1 is a schematic, cross-sectional view of a printed circuit board 1 comprising an electrically insulating substrate 2 (for example of an epoxy resin) as well as an electroconductive track 3 of copper. A contact face 4, which in practice will be an expansion of track 3, is provided with a thin layer of tin and is situated at an end of track 3. The substrate supports a leaded electric component 5 which, in this case, represents an electrolytic capacitor. This capacitor is provided with two leads, one of which, referenced 6, is shown. Both leads are secured via separate wire clamps to two individual contact faces of the printed circuit board. Fig. 1 only shows the connection between the lead 6 and the contact face 4 via the L-shaped wire clamp 7. A thin solder layer 8 is situated between the contact face 4 and the wire clamp 7. In the manufacture of the printed circuit board in accordance with the invention, the wire clamp 7 and further SMD components, if any, are provided on the contact face 4 by means of an SMD-placement machine, and held in place by means of a drop of an adhesive (not shown). Subsequently, the printed circuit board is subjected to a wave-soldering treatment. In this treatment, the solder layer 8 is formed between the wire clamp 7 and the contact face 4. Finally, the component 5 is manually secured to the printed circuit board by tightly securing the lead 6 in the aperture 9 of the wire clamp 7. If the lead 6 is to be permanently secured, the aperture 9 can be provided with clamping members 10. Withdrawal of the component 5 causes these members to penetrate the lead 6 at the location of the aperture 9. Such a clamping member is commonly referred to as "Chinese finger clamp". Fig. 2 shows three embodiments of wire clamps which can very successfully be used in the method in accordance with the invention. Fig. 2-a shows an L- shaped wire clamp 11 of a resilient, electroconductive material, such as a resilient metal alloy, for example steel or copper. One of the two legs of the wire clamp is provided with a channel 12 having a slightly widened end portion 13. Preferably, the leg 14 is provided with a solderable layer, preferably of lead-tin solder, on the surface facing away from the leg 15. The Figs. 2-b and 2-c show two other, U-shaped wire clamps 21 and 31, respectively. One of the peripheral legs of both wire clamps is provided with a channel 22 having a widened end portion or a through-hole 32, respectively. The U-shaped wire clamps can be secured to a contact face of the printed circuit board in two ways, namely via the center face 23, 33, respectively, or via the leg 24, 34, respectively. In the first case, the axis of the lead will extend partly parallel to the printed circuit board. In the second case, the axis of the lead will extend approximately at right angles to the printed circuit board. The way in which the clamps are placed is governed, of course, by the intended layout of the printed circuit board. The invention relates to a printed circuit board provided with at least one component having one or more leads which are secured to contact faces of the printed circuit board. In accordance with the invention, the leads of the component are secured to the printed circuit board via wire clamps soldered onto the surface of the contact faces. The formation of through-holes in the printed circuit board is rendered superfluous by said wire clamps. For the leaded components use can be made of resistors and capacitors, but also of a single electroconductive wire. The invention also provides a method of manufacturing the invented printed circuit board.

Claims: CLAIMS: 1. A printed circuit board provided v ith at least one component having one or more leads which are secured to contact faces of the printed circuit board, characterized in that the leads of the component are secured to the printed circuit board via wire clamps soldered onto the surface of the contact faces. 2. A method of securing a component having one or more leads to a printed circuit board, at least one lead of the component being secured to the surface of a contact face of the printed circuit board, characterized in that the lead of the component is secured to the printed circuit board via a wire clamp soldered onto the surface of the contact face. 3. A method as claimed in claim 2, characterized in that the wire clamp is secured to the lead, whereafter said wire clamp is soldered onto the surface of the contact face. 4. A method as claimed in claim 2, characterized in that the wire clamp is soldered onto the surface of the contact face, whereafter the component is secured to the wire clamp via the lead. 5. A method as claimed in claim 4, characterized in that the wire clamp is secured to the contact face of the printed circuit board by means of a component placement machine and a wave-soldering process.

Inventors: VAN LERBERGHE STEVEN JAN WILLE, VAN LERBERGHE, STEVEN, JAN, WILLEM
Applicants: KONINKL PHILIPS ELECTRONICS NV, PHILIPS SVENSKA AB, KONINKLIJKE PHILIPS ELECTRONICS N.V., PHILIPS AB
Application year: 1998
Main classification: H05K3
IPC codes: H05K1, H05K3