EP1754285B1 - Press-in contact - Google Patents

Description

The invention relates to a press-fit.

Such press-fit contacts are used to produce electrical, solder-free press-fit contacts, which are for this purpose pressed in particular in durchmetallisierte holes of printed circuit boards.

Here are Einpresskontakte with massive or elastic press-in areas, which are in the respective bore after pressing the press-in contact. Massive press-in areas have significant disadvantages compared to elastic press-in zones due to their low flexibility. In particular, damage to the bores and thus impairments in the contacting to be produced can easily be obtained when pressing in press-fit contacts with massive press-fit zones.

For the production of press-fit contacts with elastic press-in areas, in particular punching methods can be used. Such press-in contacts have two spaced-apart legs in the press-in area.

The legs of the press-fit are made by stamping into a solid material, wherein a correspondingly large material surface is required for punching the hole between the legs. Accordingly, the press-fit contacts thus produced generally have a flat, flat shape. When these contacts are introduced into the circular bores, substantially two contact surfaces of the press-fit contact offset by 180 ° from one another on the wall of the bore are formed, which are formed by the narrow sides of the press-fit contact.

Since the press-in contact rests only with its narrow sides on the wall of the bore, this results in an inadequate and fault-prone, especially vulnerable to tolerances of the individual components electrical contact.

The US Pat. No. 3,846,741 describes press-fit contacts for insertion into holes in printed circuit boards made by bending metal strips. In particular, a press-in contact of two superimposed metal strips may be formed, whose lower ends are bent so that they form discrete legs, which are pressed under pressure into the respective bore.

In this method, too, elongated press-fit contacts are obtained whose geometry is insufficiently adapted to the circular cross section of the bores.

From the DE 202 18 295 U1 a contact element for printed circuit boards is known, which has a pin part which consists of two mutually spaced arms and a solid, adjoining the arms body. The arms have at least four longitudinally extending outer edges, which are movable in pairs against a restoring force to each other.

The US 5,145,407 describes a one-piece contact element, which has a solid head part, on which two mutually spaced arms are provided. When pressing the arms into a hole, the arms are pressed together. By the case exerted spring force of the arms, the contact element is held in the bore.

The invention has for its object to provide a press-fit, on the one hand cost-effective and efficient to produce and on the other hand has good and reproducible mechanical and electrical contact properties.

To solve this problem, the features of claim 1 are provided. Advantageous embodiments and expedient developments of the invention are described in the subclaims.

The press-fit contact according to the invention comprises a contact body and two limbs formed integrally therewith, which are separated by a parting surface produced by chipless machining and are expanded within a press-in area and spaced apart from one another. In addition, a subsequent to the press-in tip is provided, which are formed by the converging free ends of the legs.

According to the invention, the press-in contact has a connection region which is formed by the contact body and adjoining segments of the legs, which lie close to one another. At this connection area then close to the press-fit forming, mutually expanded segments of the legs. With the segments forming the connection region of the legs an efficient tolerance compensation is created. This is done by the stiffness of the press-in contact is reduced in the connection area by the separation of the legs in the connection area, which ensures that even with tolerance-related axial offset between press-fit and bore the allowable forces on the circuit board and the press-in during the pressing process are not exceeded.

The press-fit contact according to the invention can be produced simply and efficiently. For this purpose, legs are incorporated by means of a chipless machining process in a contact body forming a solid part, which open out at the remaining segment of the contact body. Preferably, the legs are made by shearing the contact body. The subsequent widening of the legs in the press-in area then preferably takes place by means of a dome.

Advantageously, tools are used which not only allow processing of a single press-fit, but a simultaneous processing of several press-fit. This leads to an extremely efficient production of press-fit contacts.

Another significant advantage of the press-fit according to the invention is that the shape of the circular metallized hole of a printed circuit board, in which the press-fit is pressed, can be adjusted, resulting in a particularly high quality of contact, which in particular also largely insensitive to Tolerances of the individual components of the contact is.

In particular, it is advantageous that a high current-carrying capacity of the contacting is obtained with the press-fit contact according to the invention, which is required in particular for high-current applications.

According to a particularly advantageous embodiment of the invention, the contact body of the press-in contact has a square cross-section. Since the limbs are produced by cutting or, in particular, shearing one end of the contact body, the sum of the cross sections of the limbs in the press-in region corresponds again, at least approximately, to the quadratic surface of the contact body. This square cross-sectional area of the legs in the press-fit region represents a geometrically optimal adaptation to the circular contour of the bore.

This results in a symmetrical force distribution of the contact forces acting between the legs of the press-fit contact and the wall of the bore. The contact forces thereby run with respect to the center of the bore in the radial direction, wherein the contact points between the press-in contact and the bore are each offset by 90 ° to each other. This means a symmetrical distribution of the contact forces and thus a torque-free and centric mounting of the press-fit in the bore.

Furthermore, it is advantageous that a large conductor cross section within the bore is obtained by the total square surface of the legs of the press-fit within the bore. Due to the permissible bore tolerances, the conductor cross section can amount to approximately 60 to 80% of the bore cross section.

Particularly advantageously, the outer edges of the legs of the press-in contact at least in the press-in each have a drawn or embossed radius. These radii form four large-scale, by clearances clearly limited gas-tight connections with the wall of the bore, whereby a corrosion-resistant, high-current loadable contact between the press-in contact and bore is obtained.

By forming the free ends of the press-fit in the form of a tip insertion of the press-in contact in the respective bore is greatly facilitated.

In an advantageous embodiment, when press-fitted into the bore, the free ends protrude beyond the underside of the bore. Then they can be bent and pressed against the lower edge of the bore, whereby a positive connection of the bent tip with the circuit board is formed. The connection formed in this way corresponds to a riveted connection and leads to a very good hold of the press-fit contact in the bore. In principle, press-fit contacts can also be used as pure mechanical fixing elements without electrical function in this way.

In general, it is advantageous that the press-fit region of the press-fit contact according to the invention has good elastic properties due to its shape. Consequently, instead of the commonly used materials such as copper alloys, the press-fit contact may in particular also consist of brass, ie a material with poor spring properties but very high conductivity values.

Figur 1a:

Schematische Darstellung eines Ausführungsbeispiels des erfin- dungsgemäßen Einpresskontakts.

Figur 2:

Querschnitt durch eine Bohrung einer Leiterplatte mit einem darin eingepressten Einpresskontakt gemäß den Figuren 1a, b.

Figur 3:

Schematische Darstellung eines Kontaktkörpers zur Herstellung eines Einpresskontakts gemäß Figur 1.

Figur 4:

Querschnitt durch ein Prägewerkzeug zum Prägen von Kontakt- körpern gemäß Figur 3.

Figur 5:

Querschnitt durch ein Scherwerkzeug zum Scheren von Kon- taktkörpem gemäß Figur 3.

Figur 6:

Kontaktkörper mit an diesem ausmündenden Schenkeln, herge- stellt mit dem Scherwerkzeug gemäß Figur 5.

Figur 7:

Querschnitt durch ein Aufweitungswerkzeug zur Aufweitung der Schenkel des Kontaktkörpers gemäß Figur 5.

The invention will be explained below with reference to the drawings. Show it

FIG. 1a

Schematic representation of an embodiment of the invention Einpresskontakts.

FIG. 2:

Cross-section through a bore of a printed circuit board with a press-fit contact pressed in according to the FIGS. 1a , b.

FIG. 3:

Schematic representation of a contact body for producing a press-fit according to FIG. 1 ,

FIG. 4:

Cross section through an embossing tool for embossing contact bodies according to FIG. 3 ,

FIG. 5:

Cross section through a shearing tool for shearing contact bodies according to FIG. 3 ,

FIG. 6:

Contact body with thighs opening at this end, produced with the shearing tool according to FIG FIG. 5 ,

FIG. 7:

Cross section through a widening tool for widening the legs of the contact body according to FIG. 5 ,

The FIGS. 1a and 1b show an embodiment of a press-fit 1. FIG. 1a shows a side view of the press-fit 1, Figure 1 b a cross section along the line A in FIG. 1a , The press-fit 1 can, as in FIG. 2 shown schematically, are pressed into a durchmetallisierte hole 2 of a printed circuit board, wherein the bore 2 has a circular cross-section.

The press-in contact 1 consists in the present case of a brass part. In this case, the press-fit 1 a contact body 3, on the underside of two legs 4 open freely. The limbs 4 are formed by cutting or shearing a separation along a separation surface is introduced into a segment of the contact body 3, so that the legs 4 connect to the remaining solid segment of the contact body 3. The legs 4 are thus formed integrally with the contact body 3. The legs 4 are identical and symmetrical to the formed in the longitudinal direction of the press-in contact 1 extending plane of symmetry.

The contact body 3 has a rectangular, in the present case a square cross-section which is constant over its length. Since the legs 4 are formed by shearing or cutting from the contact bodies 3, these each have a constant over their length rectangular cross section, wherein the cross sections complement the square cross section of the contact body 3. Only in the region of the free ends of the legs 4 whose cross-sections can be slightly tapered to facilitate the insertion of the press-fit 1 in the bore 2.

The press-in contact 1 is as out FIG. 1a can be seen, divided into different areas, namely a connection region 5 at its upper end, an adjoining press-in area 6 and a tip 7 at its lower end.

The connection region 5, which serves for the electrical connection of external units to the press-fit contact 1, consists of the solid contact body 3 and the adjoining upper segments of the legs 4 which abut each other separated by a separating surface segment 8. The connection region 5 is completed by the region of the legs 4, which diverge from the separation surface segment 8 and thus enclose a gap in the form of a gusset 9.

In the subsequent press-in area 6, the legs 4 are widened by means of suitable tools and are at a greater distance from each other. As a result, the legs 4 form an elastic press-in area 6. As a result of the tool machining, the inner sides have a smoothed surface in this area. The legs 4 in the region of the press-in area 6 form an eyelet, the outer dimension of which is greater than the diameter of the bore 2 into which the press-fit contact 1 is to be pressed. The gap between the legs 4 in the press-in area 6 forms a defined widening region 10. At the press-in area 6, the tip 7 of the press-fit contact 1 connects. The tip 7 is formed by the free ends of the legs 4. In the upper region of the tip 7, the legs 4 run towards each other at predetermined angles of inclination and enclose a gap in the form of a gusset 11. At the front end of the tip 7, the free ends of the legs 4 run substantially parallel. The legs 4 are separated by a separating gap 12.

As in particular from FIG. 1b can be seen, the outer edges of the legs 4 in the press-6 6 radii. In principle, the outer edges of the press-fit contact 1 can have drawn or embossed radii 13 over their entire lengths. In the present case, the outer edges of the legs 4 in the press-in area 6 by a separate step embossed radii 13.

For pressing the press-fit 1 into the bore 2, the tip 7 of the press-in contact 1 is first introduced into the bore 2. Since the cross sections of the legs 4 are reduced in the region of the tip 7 and the free ends of the legs 4 converge, the outer dimension is smaller than the diameter of the bore 2, whereby a simple insertion of the tip 7 is ensured in the bore 2.

Subsequently, the press-in area 6 of the press-fit 1 is pressed into the bore 2, wherein the legs 4 are pressed against each other in the press-in 6 during pressing and, as in FIG. 2 shown lying in the hole 2.

By the closely spaced, separated by the interface segment 8 segments of the legs 4 in the connection region 5, the elastic properties of the press-fit 1 are improved to the effect that a tolerance compensation is created. This means that with it the stiffness of the press-fit 1 in the connection region 5 is reduced. This will not exceed the allowable forces on the circuit board and the press-in 6 during the press-in even with tolerance-induced axial offset between press-fit 1 and 2 hole, especially in multiple arrangements of press-fit contacts 1.

FIG. 2 shows the pressed into the hole 2 legs 4 in the press-in 6. Since the legs 4 are made by shearing or cutting from the contact body 3 and this has a square cross-section, the legs 4 in the press-in area 6 to this square cross-sectional area complement each other optimally the geometry of the circular bore 2 is adjusted. By the geometry of the legs 4 it is achieved that the contact forces F between press-fit contact 1 and bore 2 in the radial direction and rotationally symmetrical with respect to the center of the bore 2 act, as in FIG. 2 is shown. As a result, a torque-free, centric secure mounting of the press-fit 1 in the bore 2 is obtained. Furthermore, the radii 13 of the legs 4 form large, gas-tight contact surfaces 2a with the bore 2. The contact surfaces 2a are clearly bounded by subsequent free spaces 2b, resulting in a defined surface pressure between press-fit 1 and the bore 2. In the free spaces 2b soiling and foreign layers can be displaced during pressing. The sum of the contact surfaces 2a of the gas-tight connections produced in this way is generally greater than the cross-section of the press-fit contact 1. This results in a very low electrical contact resistance and a correspondingly high current-carrying capacity. Finally, the square cross-sectional arrangement of the legs 4 forms a large conductor cross-section in the smallest possible bore 2.

The tip 7 of the press-fit contact 1 pressed into the bore 2 projects slightly beyond the lower edge of the bore 2. If necessary, the exposed ends of the legs 4 can be bent and pressed against the edge of the bore 2, whereby a riveted joint is formed, which ensures a further improved mechanical support of the press-fit 1.

The FIGS. 3 to 7 show the method for producing the press-fit 1 according to the FIGS. 1a and 1b ,

FIG. 3 shows the starting material for producing a press-fit 1, namely in the form of a contact body 3, which is a solid part of brass. This has in the present case, the contact body 3 a constant over its length square cross-section. The outer edges of the contact body 3 may have drawn or embossed radii 13.

The FIGS. 4, 5 and 7 show cross-sectional representations of tools by means of which a press-fit contact 1 is produced by chipless machining processes from the contact body 3. The tools are designed in such a way that a plurality of contact bodies 3 can be machined at the same time with these, so that in particular raster arrangements with a plurality of press-fit contacts 1 can be produced in particular. In the FIGS. 4, 5 . 7 tools for simultaneous processing of four contact bodies 3 are provided. In principle, the number of contact bodies 3 to be machined simultaneously can also vary.

FIG. 4 shows an embossing tool 14. This embossing tool 14 has four embossing molds 15 for receiving contact bodies 3. The longitudinal axis of a contact body 3 mounted in a stamping mold 15 runs perpendicular to the plane of the drawing. The stamping molds 15 are adapted to the cross sections of the contact body 3. Due to the rounded corners of the embossing molds 3, the outer edges of the contact body 3 are impressed with radii 13 in the press-in region 6 of the respective protruding press-fit contact 1. Furthermore, each stamping mold 15 has at least one projection 15a with which a notch is introduced into the respective contact body 3.

Subsequently, the contact body 3 in the in FIG. 5 edited shear tool 16 edited. The shearing tool 16 has receptacles 17 for the contact body 3 and an arrangement of shear punches 18a, b. These Form first shear stamp 18a, which is used to shear a contact body 3 in the plane of FIG. 5 are moved down, and second shear stamps 18b, which are moved upward.

Each contact body 3 is located in each case on a first and second shear punch 18a, b in the receptacle 17, wherein the longitudinal axis of the contact body 3 is perpendicular to the plane of the drawing. By the opposite shear movements of acting on a contact body 3 first and second shear punch 18a, b, the lower portion of a contact body 3 is sheared to form two separated by a separating surface legs 4. The obtained after a shearing contact body 3 with the two legs 4 is in FIG. 6 shown. Due to the formation of the shear punches 18a, b form the opening on the contact body 3 leg 4 a V-shaped arrangement.

Before further processing of the contact body 3 in the in FIG. 7 shown widening tool 19, the legs 4 of the contact body 3 are bent together so that they rest against each other again. The pre-machined contact bodies 3 are introduced into receptacles 20 of the expansion tool 19. The longitudinal axes of the contact body 3 mounted there are perpendicular to the plane of the drawing.

At the receptacles 20 open out channels 21, in each of which a mandrel 22 is inserted to widen the legs 4 in the press-in region 6 of the press-fit 1. Since the legs 4 are pressed apart during the expansion by means of the mandrel 22, the widths of the receptacles 20 are greater than the width of the contact body 3, so that the legs 4 can escape laterally when pressing the mandrel 22. The space between the legs 4 forming the widening region 10 in the press-in region 6 is determined by the shape of the mandrel 22. The inner sides of the legs 4 are smoothed by machining with the mandrel 22. The with the embossing tool 14 according to FIG. 3 stamped notch in the contact body 3 serves as an insertion aid for the mandrel 22. With the tools according to FIGS. 4, 5 . 7 is the press-fit 1 simple and efficient to produce. Further processing steps are not required.

LIST OF REFERENCE NUMBERS

(1)

press-fit

(2)

drilling

(2a)

contact area

(2 B)

free space

(3)

Contact body

(4)

leg

(5)

connecting region

(6)

press-in

(7)

top

(8th)

Separating surface segment

(9)

gore

(10)

widening range

(11)

gore

(12)

separating gap

(13)

radius

(14)

embossing tool

(15)

embossing dies

(15a)

head Start

(16)

shear tool

(17)

Recordings

(18a)

shear temple

(18b)

shear temple

(19)

flaring tool

(20)

admission

(21)

channel

(22)

mandrel

Claims (12)

1. Press-in contact for pressing into a through-plated bore (2) of a circuitboard, with a contact body at which two limbs integrally formed therewith open, which are separated by a separating surface produced by means of processing without cutting and which are widened within a press-in region and arranged at a spacing from one another, and with a tip which is connected with the press-in region and formed by the limb free ends running towards one another, characterised in that a joining region (5) connected with the press-in region is provided, the region (5) being formed by the contact body (3) and segments of the limbs (4) connected therewith and bearing against one another, wherein the stiffness of the press-in contact in the joining region (5) is reduced by the separation of the limbs (4) in the joining region.
2. Press-in contact according to claim 1, characterised in that the contact body (3) has a constant rectangular cross-section over its length.
3. Press-in contact according to claim 2, characterised in that the contact body (3) has a square cross-section.
4. Press-in contact according to any one of claims 1 to 3, characterised in that the limbs (4) in the area of the press-in region (6) each have a constant cross-section, wherein the sum of the cross-sections of the limbs (4) corresponds with the cross-section of the contact body (3).
5. Press-in contact according to any one of claims 1 to 4, characterised in that the outer edges of the limbs (4) at least in the press-in region (6) each have a radius (13).
6. Press-in contact according to one of claims 4 and 5, characterised in that that the freed limbs (4) form in the press-in region (6) an eye having an outer diameter greater than the diameter of the bore (2).
7. Press-in contact according to any one of claims 4 to 6, characterised in that after pressing into the bore (2) the limb segments lie in the area of the press-in region (6) in the bore (2).
8. Press-in contact according to claim 7, characterised in that after pressing into the bore (2) the radii (13) of the limbs (4) form a gas-tight connection with the wall of the bore (2).
9. Press-in contact according to claim 8, characterised in that the bore (2) has a circular cross-section, wherein the limbs (4) pressed into this exert on the wall of the bore (2) contact forces running in radial direction.
10. Press-in contact according to any one of claims 1 to 9, characterised in that the cross-sections of the limbs (4) in the region of the tip (7) are smaller than in the press-in region (6).
11. Press-in contact according to claim 10, characterised in that after pressing into the bore (2) the free ends, which protrude therebeyond, of the limbs (4) are bent out against the edge of the bore (2).
12. Press-in contact according to any one of claims 1 to 11, characterised that this consists of brass.

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