WO2004006636A1

WO2004006636A1 - Component for assembling a printed circuit board

Info

Publication number: WO2004006636A1
Application number: PCT/EP2003/006811
Authority: WO
Inventors: Karl Ludwig Kilian
Original assignee: Hartmann Codier Gmbh & Co. Kg
Priority date: 2002-07-03
Filing date: 2003-06-27
Publication date: 2004-01-15
Also published as: AU2003249888A1; DE10229953A1

Abstract

The invention relates to a component (1, 10), particularly a rotary switch or plug connector, for assembling a printed circuit board. Said component comprises a housing (2, 20) that has an assembly face (3, 30) and a number of connector pins (4, 40) which extend through the assembly face of said housing. A recess (5, 50) which is disposed on the assembly surface of the housing (2, 20) and in which a solder preform (6, 60) fully encompassing the respective connector pin (4, 40) is inserted, is assigned to each connector pin (4, 40). The inventive component (1, 10) is particularly suitable in connection with the through hole reflow (THR) method.

Description

description

Component for PCB assembly

The invention relates to a component for printed circuit board assembly, with a housing having a mounting side and with a number of connecting pins which are led out from the mounting side, wherein each connecting pin is assigned a recess formed with a soldering agent depot in the housing or in a carrier element integrated in the housing on the mounting side. In this context, component is understood in particular to be a rotary or rotary coding switch or a pin or terminal strip.

Such a surface-mounted component, a so-called surface-mounted device (SMD), for example a rotary or rotary coding switch known from EP 1 138 997 B1 and from WO 01/97240 A1 (PCT / E P01 / 06521), is placed on a printed circuit board put on and soldered there. For the circuit board assembly, a number of solder paste depots, so-called pads, are applied to the circuit board in accordance with the number of connection pins or connection pins of the component. The component is placed on these pads, which are adapted to the grid of the connection pins, and then soldered by the action of heat without further solder. The pads are applied to the circuit board surface by means of stencil printing, screen printing or dispensing.

This type of application of solder paste or solder according to a predefined connection pattern also takes place in the so-called THR technology (through-hole reflow technology). Here, the printed circuit board is provided with plated-through holes, the applied solder paste filling the plated-through holes. When assembling the components, the connection pins of the component to be mounted on the printed circuit board push the solder paste at least partially through the hole, so that during subsequent reflow soldering, the respective connection pin is soldered both on the assembly side facing the component and on the opposite underside of the PCB is done. In contrast, in TH technology (through-hole technology), in which no through-plating the circuit board holes is necessary, the connection pins are inserted through the holes and soldered on the underside of the circuit board opposite the component.

Compared to SM technology (surface mounting technology), THR technology has the advantage of both a comparatively firm mechanical fit of the component on the circuit board and a comparatively good electrical resilience. This THR technology can also be carried out together with the previous SMD technology in a reflow process (heating passage), so that the separate soldering of the components is then no longer necessary.

Frequently, however, very high demands are placed in particular on a mechanically firm fit of the component on the printed circuit board, which are not adequately met by SM technology. A reliable mechanical hold on the circuit board is extremely desirable, particularly when mounting rotary switches or also pin or terminal strips on the circuit board. In particular, in the case of components of this type, due to their intended use, such large torques or bending moments are frequently exerted on the soldering points via the connecting pins that the soldered connection breaks up and the electrical contact between the corresponding connecting pin and the connecting point on the printed circuit board is thereby interrupted.

For replacement purposes in an already populated circuit board with limited installation space, it is known from DE 198 07 279 C2 to provide the connection pins of a component with solder deposits prior to its assembly. For this purpose, a separate processing carrier is provided which has depressions filled with solder for receiving the connection pins. The solder without connection to the wells adheres to the connecting pins after heating and then centrifuging and cooling.

From DE 100 84 996 T1 it is known to use a wafer carrying a soldering agent with a hole pattern corresponding to the pin pattern of a connector for a printed circuit board during soldering processes. On one side of the hole or on two opposite sides Hole sides of each hole of the hole pattern are made in the wafer grooves into which solder lengths separated according to the groove length are inserted. Instead of using a separate wafer, the solder segments formed by the grooves and the solder lengths inserted therein can also be integrated as part of the connector. In this embodiment, too, the division of the solder material forms two separate solder segments on opposite sides of each connecting pin, the solder segments being spaced apart from the respective connecting pin, also at their closest location. This measure, which requires a great deal of effort in the production of such connectors, is intended to prevent a single massive solder mass being formed during the melting of the solder material.

The invention is based on the object of specifying a component with a simple manufacturing technology, in particular a rotary switch or a pin strip, which can be mounted on a printed circuit board with the formation of a particularly firm mechanical seat.

This object is achieved according to the invention by the features of claim 1. For this purpose, each connection pin led out of the housing of the component on the assembly side is assigned a recess made on the assembly side into the housing, into which a solder preform completely surrounding the respective connection pin is inserted in a form-fitting manner. The assembly side of the component housing is the side of the housing which faces the surface of the circuit board during printed circuit board assembly and is also referred to below as the underside of the housing. A recess is also understood to mean a receiving space which is formed between housing webs which protrude on the underside of the housing.

The recesses can also be formed in a support element integrated into the housing on the assembly side. The carrier element is thus an integral part of the component housing. The carrier element shape is therefore a component of the housing injection mold for the manufacture of the housing. The advantage of this embodiment is, in particular, that the carrier element having the recesses can be offset from the rest of the component housing in a material-saving manner. The carrier element can also be made from a component housing that is likewise consist of heat-resistant material, which, like the housing material, is expediently a suitable plastic.

The recesses themselves can practically have any geometry. The recesses are expediently round, in particular circular, or rectangular, in particular square. Regardless of the geometry of the recesses, this is at least approximately symmetrical about a central passage opening, through which the respective connector pin is guided out of the housing on the assembly side.

The symmetrical design of the recesses enables the use of prefabricated solder or solder preforms, so-called solder preforms. Such solder preforms can have practically any shape or geometry. These preforms have central through openings adapted to the geometry and the dimensions of the connecting pins. These can be circular or square depending on the cross-sectional shapes of the connection pins. This particularly simplifies automatic insertion of the solder preforms into the recesses integrated in the component housing. Ultimately, either the recesses can be adapted in terms of their geometry to preforms available on the market, or else this can be adapted to the recesses and pin cross sections that are then predetermined.

The component is particularly easy to manufacture with regard to the recesses, since the recesses are easy to manufacture due to their symmetrical design around the central position of the respective connecting pin and without any distance therefrom. By providing such components with solder depots already inserted in the recesses, a high degree of manufacture is achieved with regard to the component itself, so that it is suitable for printed circuit board assembly without intermediate assembly steps. Thereby, the TH technology has already been implemented in the component itself with respect to the carrier element integrated in its housing. The prefabricated component with solder depot or solder preforms already introduced into the recesses is therefore particularly advantageous for use in the THR process. When assembling or assembling printed circuit boards with subsequent reflow soldering, the soldering agent depots inserted in the recesses also provide soldering agent in addition to the pads already provided in the area of the plated-through holes in the printed circuit board, which can be soldered to the pads on the printed circuit board during the reflow Process connects. Overall, a mechanically particularly stable fastening of the component to the printed circuit board is thus produced with a high electrical load capacity. This stable fixation is particularly advantageous for mechanically loaded rotary switches and pin or terminal strips.

Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. In it show:

1a to 1c in partially sectioned side views or in a bottom view of the mounting side of a component housing, a rotary switch with integrated soldering agent depot, and

2a to 2c, each in a view according to FIG. 1, a THR pin strip with solder preforms.

Corresponding parts are provided with the same reference symbols in all figures.

1a to 1b show a side view, a front view or a bottom view of a rotary or rotary coding switch 1 as a THR component for circuit board assembly. The rotary switch 1 comprises a component housing 2, in particular made of plastic. On the underside of the housing or the mounting side 3 facing a printed circuit board LP, in the area of each connecting pin 4 which is led out of the housing 2 there is a recess 5 associated therewith, which concentrically surrounds the respective connecting pin 4.

As can be seen comparatively clearly from FIG. 1 c, these recesses 5 are rectangular. In principle, practically any recess shapes or geometries, for example round or oval recesses 5, can be provided. In the Recesses 5 are introduced into solder deposits 6. For this purpose, already prepared solder preforms 6 (solder preforms) are inserted into the respective recesses 5.

The recesses 5, as can be seen in particular from FIGS. 1 a and 1 b, are expediently formed in a carrier element 7 which is integrated into the component housing 2 on the mounting side 3. For this purpose, the carrier element 7 is injected together with the housing 2 of the component or rotary switch 1. The carrier element 7 is therefore part of the housing injection mold provided for the component production.

2a to 2c again show a side view, a front view or a bottom view of the mounting side 30 of a THR pin strip 10 for mounting on a printed circuit board. The pin header 10 in turn has a housing 20 and from this assembly side, ie. H. on the housing underside 30 lead pins 40.

In the area of the mounting side 30 of the pin strip 10 which in turn faces the printed circuit board LP, a number of recesses 50 corresponding to the number of connecting pins 40 for receiving solder depots or preforms 60 are made in the housing underside 30 in the housing 20.

The recesses 50 can in turn be made in a corresponding carrier element 70, which is then also part of the pin header housing 20. The solder depots 60 are in turn expediently prefabricated solder preforms.

For the through-hole reflow or pin-in-paste method, through-holes B are provided in the printed circuit board LP, which are filled with solder paste or solder P to form so-called pads. When mounting or mounting the printed circuit board, the connecting pins 4, 40 of the component 1, 10 push part of the solder paste P through the hole B onto the underside of the printed circuit board, so that the connecting pins 4 and 40 are also in contact with solder P there on the free end , The formation of recesses 5, 50 integrated in the housing 2, 20 for accommodating solder deposits 6 or 60 is practically advantageous for all TH or THR components for mounting on printed circuit boards. If their tight fit and reliable electrical contacting is desired or required, additional solder is provided in addition to the pads P by means of the solder depot 6 or 60 which has already been introduced into the recesses 5, 50 and is therefore available for the actual soldering process. Otherwise, the same components 1, 10 can also be installed with empty recesses 5 and 50, ie without solder deposits 6.60 introduced there.

The integration of a carrier element 7.70 having the recesses 5.50 in the component housing 2.20 enables the carrier element 7.70 with the recesses 5.50 to be set down in a material-saving manner with respect to the remaining component housing 2 or 20. 1b, the length and / or width dimensions of the carrier element 7.70 are then smaller than those of the housing 2.20, at least in the region of the housing bottom or mounting side 3 or 30.

Different materials or plastics can also be used for the carrier element 7.70 on the one hand and for the actual component housing 2.20 on the other hand, which is advantageous with regard to the heat resistance required for the soldering or reflow process. In this way, the requirement can be met to a particular degree that when the component 1, 10 is soldered to the corresponding printed circuit board connections or pads P, the housing parts 2,7; which come into direct or indirect thermal contact with the heated and melted solder 6.60, P; 20.70 of component 1 or 10 must withstand the corresponding thermal loads without being destroyed. LIST OF REFERENCE NUMBERS

1 rotary switch, 20 housing

3.30 mounting / housing underside, 40 connecting pin

5.50 recess

6.60 Soldering agent / Λ / orform

7.70 support element

10 pin header

B hole

LP circuit board

P Lotdepot / Pad

Claims

Expectations

1. Component (1, 10) for mounting on a printed circuit board, with a housing (2.20) having a mounting side (3.30) and with a number of connecting pins (4.40) led out of this on the mounting side, each connecting pin ( 4.40) is assigned a recess (5.50) with a solder depot (6.60) formed in the housing (2.20) on the assembly side or in a carrier element (7.70) integrated in the assembly (2.20) on the assembly side, characterized in that the respective recess (5, 50) is designed such that one in the

Recess (5.50) inserted solder preform (6.60) completely surrounds the respective connector pin (4.40).

2. Component according to claim 1, 5 characterized in that the recess (5.50) and the solder preform (6.60) inserted therein concentrically surround the respective connecting pin (4.40).

3. The component according to claim 1 or 2, 0, characterized in that the solder preform (6, 60) lies positively in the respective recess (5, 50).

4. Component according to one of claims 1 to 3, 5 characterized in that the solder preforms (6, 60) have central through openings adapted to the geometry and to the dimensions of the connecting pins (4, 40).

5. Component according to one of claims 1 to 4, o characterized in that the carrier element (7.70) has smaller length and / or width dimensions than the housing (2.20) on its mounting side (3.30).