EP3224908B1 - Base strip for connection to a printed circuit board - Google Patents

Description

The invention relates to a base strip for connection to a printed circuit board according to the preamble of claim 1.

Such a base strip is used for electrically connecting one or more connector elements to a printed circuit board. For this purpose, the base strip can be attached to a printed circuit board and electrically connected to the printed circuit board via suitable contact elements. One or more male members may be matingly engaged with the header to connect the male members to the circuit board in this manner.

Such a baseboard has a longitudinally along a longitudinal direction extending first side wall and a longitudinally along the longitudinal direction extending second side wall. The side walls are spaced apart along a transverse direction transverse to the longitudinal direction, so that between the side walls a receiving space is formed into which one or more plug elements can be inserted in a plug-in direction, so that the plug elements are received in the inserted space in the receiving space. The side walls are interconnected by a base extending transversely between the side walls, the base having a plurality of receiving apertures for receiving electrical contact elements, e.g. Contact pins, is provided.

Such a baseboard is conventionally manufactured in one piece from plastic. The preparation takes place here in a suitable plastic molding tool at elevated temperature. After removal of the workpiece from the tool, the workpiece cools down, which may be accompanied by shrinkage of material on the workpiece. If different shrinkage of material occurs at different sections of the workpiece, this can lead to distortion and deformation on the base strip produced in this way.

Due to shrinkage effects, a manufactured base strip can thus deviate in shape from a desired actual shape. In particular, curvatures can occur on individual sections of the base strip or the base strip can be bent overall.

Today, such baseboards are used in particular in the context of automated assembly of printed circuit boards. A base strip is in this case gripped in an automated manner by a placement machine and attached together with other components to a circuit board, wherein the components attached to the circuit board components are then soldered in a so-called reflow soldering together with the circuit board. In particular, the so-called through-hole reflow soldering (referred to as "THR" soldering) is used, in which plug contacts are inserted into openings on the printed circuit board. If, however, the base strip has an excessive deviation in shape from its actual desired shape owing to shrinkage effects, soldering of contact elements of the base strip can lead to errors and thus to possibly incorrectly produced solder joints.

This should be avoided.

Such shrinkage effects that can lead to changes in the shape of a base bar, strengthen even in hochpoligen baseboards, ie comparatively large baseboards with a variety of contact elements, for example, more than twelve contacts.

Most different types of baseboards are known from the prior art and, for example, in the EP 1 672 744 A2 , of the DE 20 2006 018 590 U1 , of the EP 0 748 005 A1 , of the US 6,645,005 , of the JP H02 99583 U , of the WO 2014/049426 A2 , and the DE 10 2004 060782 B3 described.

The object of the present invention is to provide a base strip which may have a reduced shrinkage and, associated therewith, a reduced shape deviation from a desired shape.

This object is achieved by an article having the features of claim 1. Accordingly, the center of gravity of the base strip corresponds to the geometric center of gravity of an imaginary cuboid enveloping the base strip.

Under the enveloping cuboid is in this context the smallest (imaginary) cuboid to understand that completely surrounds the base bar. The enveloping cuboid thus corresponds to a cuboid, which touches the base strip on its outer walls and envelops the base strip, analogous to the mathematical definition of an envelope.

A cuboid is, according to the usual definition, a geometric body with six rectangular surfaces whose angles are all right angles.

There is exactly one enveloping, imaginary cuboid, so a geometric cuboid with minimal volume that completely surrounds the base bar. The imaginary, enveloping cuboid is defined mathematically exactly.

In this context, the base strip is understood to mean a (plastic) molded part to which no contact elements have yet been attached.

The base strip is made in one piece from plastic. At the base bar contact elements can be attached to the associated receiving openings. About such contact elements, an electrical connection can be made with a printed circuit board.

The invention is based on the surprising, empirically determined finding that by a suitable choice of the position of the center of gravity of the base strip, a deformation of the base strip can be reduced by material shrinkage. The fact that the center of gravity of the base bar at least approximately (up to less than 10% accurate, preferably to less than 1% accurate, based on the overall dimensions, eg the total length, the base bar) corresponds to the center of gravity of the enveloping cuboid, results from the Base strip an advantageous material distribution. The geometric center of gravity of the enveloping cuboid lies at the geometric center of the cuboid. Here, too, the center of gravity of the base strip, so that the material of the base strip is evenly distributed around its geometric center.

Because a uniform shrinkage can set around the center of gravity, it comes in the manufacture and especially during cooling after making a baseboard to reduced deformation of the base bar, so that the base bar can be made precisely according to their desired shape.

This allows in particular a secure, reliable attachment of the base strip to a printed circuit board with reliable production of solder joints with attached to the base strip contact elements.

The insertion direction is preferably directed perpendicular to the longitudinal direction and perpendicular to the transverse direction. The side walls thus extend flat in parallel, spanned by the plug-in direction and the longitudinal direction planes and are transversely, ie along the transverse direction, spaced from each other. The base, however, is stretched by the transverse direction and the longitudinal direction and extends transversely between side walls. The base strip thus has a U-shaped basic shape into which one or more plug elements can be inserted from above into the plug-in direction.

In the receiving space of the base strip preferably a plurality of slots are defined, which are separated by along the insertion direction, projecting into the receiving space, along the longitudinal direction spaced apart guide webs are separated. In this case, for example, a slot for a (single-pole) plug element is defined between two guide webs, it being fundamentally possible to arrange a multipolar plug element at a plurality of slots of the base strips.

The guide webs on the inside of the first side wall extend along the insertion direction on the first side wall and protrude into the receiving space. However, the guide webs advantageously do not extend over the entire height of the receiving space, but rather, the first side wall projects outward beyond the guide webs with a head edge.

The guide webs extending along the plug-in direction and defining the slots also contribute to the stiffening of the base strip. The rigidity of the base strip can be further improved by extending the first side wall with a side surface just along the longitudinal direction and thus formed as a flat surface. The result is a simple to manufacture design, the material requirements compared to conventional baseboards can be reduced.

The base extending transversely between the side walls is also preferably flat on a floor pointing towards the receiving space. Dome can protrude from this floor into the receiving space, where receiving openings are arranged, through which electrical contact elements can be inserted. After the base strip has been produced, contact elements can be inserted, for example, into the receiving openings and pressed in a stamping manner with the receiving openings, so that after completion the contact elements are firmly connected to the base strip.

In an advantageous embodiment, the base on a side facing away from the receiving space on a plurality of transverse webs, which extend along the transverse direction on the outside of the base and can be transversely extending over the entire width of the base, for example. In each case two transverse webs can in this case receive in pairs a receiving opening between them, so that a contact element, when it is inserted into an associated receiving opening of the base strip, comes to rest between the transverse webs.

In principle, the base strip can be brought into contact with different contact elements. Thus, contact elements in the form of pins can be used, which are attached along the insertion direction to the base strip and protrude along the insertion direction beyond the base on the outside of the base. However, it is also conceivable to use angled contact elements in the form of L-shaped pins, which are angled in the region of the outside of the base and extend with an angled portion between the transverse webs. Such an angled pin is thus guided with its angled portion between the transverse webs.

By using such different contact elements, the base bar can be attached to a circuit board in different orientations. Thus, the base bar in a position in which the base of the circuit board is facing, be attached to an associated circuit board. Or the base bar can be attached to an associated circuit board in a position in which one of the side walls comes to rest on the circuit board.

The transverse webs preferably have a symmetrical shape (relative to a plane of symmetry extending through the center of gravity, spanned by the longitudinal direction and the plug-in direction). The transverse webs contribute to the stiffening of the base bar.

In an advantageous embodiment, the base strip is made of a liquid-crystalline polymer (English "Liquid Crystal Polymer", in short: LCP). Such a liquid-crystalline polymer has so-called mesogens which form molecular chains in the polymer. In particular, LCP has a high tensile strength and a high modulus of elasticity along its molecular axes, so that materials having excellent strength properties can be produced.

A base strip of the type described here is designed, in particular, as a high-pole base strip, that is to say as a base strip for use with a multiplicity of contact elements, for example more than twelve contact elements. For example, such a base strip having twelve, twenty-four or forty-eight receiving openings for applying contact elements. In principle, however, a base strip of the type described here can also be used as a low-pole base strip with fewer than twelve receiving openings for contact elements.

Fig. 1A

eine Seitenansicht einer Grundleiste;

Fig. 1B

eine Ansicht der Grundleiste von unten;

Fig. 1C

eine Ansicht der Grundleiste von oben;

Fig. 2A

eine Schnittansicht entlang der Linie A-A gemäß Fig. 1A;

Fig. 2B

eine Schnittansicht entlang der Linie B-B gemäß Fig. 1A ;

Fig. 3

eine ausschnittsweise Ansicht der Grundleiste von unten;

Fig. 4

eine ausschnittsweise Ansicht der Grundleiste von oben;

Fig. 5

eine Seitenansicht der Grundleiste mit einem einhüllenden Quader;

Fig. 6

die Schnittansicht gemäß Fig. 2A, zusammen mit dem einhüllenden Quader;

Fig. 7A

die Schnittansicht gemäß Fig. 2B, mit einem in eine Aufnahmeöffnung eingesteckten Kontaktelement; und

Fig. 7B

die Schnittansicht gemäß Fig. 2B, mit einem anderen in die Aufnahmeöffnung einsteckten Kontaktelement.

The idea underlying the invention will be explained in more detail with reference to the embodiments illustrated in the figures. Show it:

Fig. 1A

a side view of a baseboard;

Fig. 1B

a view of the bottom bar from below;

Fig. 1C

a view of the baseboard from above;

Fig. 2A

a sectional view taken along the line AA according to Fig. 1A ;

Fig. 2B

a sectional view taken along the line BB according to Fig. 1A ;

Fig. 3

a fragmentary view of the bottom bar from below;

Fig. 4

a fragmentary view of the baseboard from above;

Fig. 5

a side view of the base bar with an enveloping cuboid;

Fig. 6

the sectional view according to Fig. 2A , together with the enveloping cuboid;

Fig. 7A

the sectional view according to Fig. 2B with a contact element inserted in a receiving opening; and

Fig. 7B

the sectional view according to Fig. 2B , with another in the receiving opening plugged contact element.

Fig. 1A-1C to Fig. 4 show an embodiment of a base strip 1, which is made in one piece from plastic, such as LCP, and can be attached to a printed circuit board 3, to allow the electrical connection of connected with connector elements 2 lines 20 to the circuit board 3.

The molded as a one-piece plastic body base strip 1 has in profile (see the sectional views in accordance with FIGS. 2A and 2B ) has a substantially U-shaped basic shape with a base 10 and side walls 11, 12. The side walls 11, 12 extend in parallel planes and are spaced from each other along a transverse direction Q. The base 10 connects the side walls 11, 12 with each other and extends transversely between the side walls 11, 12th

The base strip 1 extends longitudinally along a longitudinal direction L. Plug elements 2 can be inserted vertically in a plug-in direction E into a receiving space 13 formed between the side walls 11, 12, wherein a plurality of slots S are defined on the base strip 1 within the receiving space 13, can be infected to the connector elements 2.

The side walls 11, 12 extend in parallel planes, which are respectively spanned by the insertion direction E and the longitudinal direction L. The base 10 in contrast extends in a plane which is spanned by the transverse direction Q and the longitudinal direction L.

The side walls 11, 12 differ from each other.

Thus, the side wall 11 extends with a side surface 110 substantially evenly along the longitudinal direction L, wherein inside this side surface 110 guide webs 112 are arranged, which extend longitudinally along the plug-in direction E and protrude into the receiving space 13 between the side walls 11, 12.

The guide webs 112 serve to define slot S within the receiving space 13. The guide webs 112 are arranged for this purpose regularly spaced from each other on the side wall 11, wherein each slot S between two guide webs 112 is associated with a receiving opening 103 on a projecting dome 102 at a bottom 100 of the base 10. Into the receiving opening 103, a contact element 14 (see Figs. 7A and 7B ) are plugged in so that it is inside protrudes into the receiving space 13 and thus can be contacted electrically with a plug element 2.

Characterized in that the guide webs 112 are longitudinally along the insertion direction E, a plug element 2 can be placed between two guide webs 112 and pushed into the receiving space 13. The guide webs 112 represent an encoding that causes a connector element 2 can be recognized only in the correct orientation to a desired slot S.

The guide webs 112 extend from the bottom 100 of the base 10 almost over the entire height of the side surface 110 of the side wall 11, the side wall 11 protruding (slightly) over the guide webs 112 at a head edge 111.

On the opposite, second side wall 12, a head strip 121 is arranged on an edge remote from the bottom 100 of the base 10 and projects outwardly beyond a flat side surface 120 of the second side wall 12. At this head strip 121 slots for coding elements can be arranged in a conventional manner, which allow coding of the base bar so that only certain connector elements 2 (namely only those that are encoded, for example, by a corresponding Gegencodierung) can be attached to the base bar 1 ,

On a side facing away from the receiving space 13 outside of the base 10 transverse transverse webs 104, 105 are arranged, which - viewed in the transverse direction Q - extend over the entire width of the base 10. In each case, two transverse webs 104, 105 enclose a receiving opening 103 between them, so that a contact element 14, when it is inserted into a receiving opening 103, comes to rest between two transverse webs 104, 105.

The transverse webs 104, 105 are - with respect to a through the center of gravity M (see Fig. 6 ) of the base strip 1 extending and spanned by the longitudinal direction L and the insertion direction E symmetry plane - formed symmetrically on the outer side 101 of the base 10.

By their shape with the along the insertion direction E longitudinally extending guide webs 112, the flat side surfaces 110, 120 of the side walls 11,12 and the transversely extending transverse webs 104, 105 on the outside of the base 10 results overall in a base strip with high rigidity.

How out Fig. 1A it can be seen, the transverse webs 104, 105 in the insertion direction E are still surmounted by engagement elements 113. By means of these engagement elements 113, the base strip 1 can be placed in a form-fitting manner on a printed circuit board 3.

In a conventional base strip 1, which is formed of plastic in a plastic molding tool at elevated temperature, resulting from cooling after manufacture and material shrinkage occurring deformations that - as shown schematically in FIG Figs. 8A and 8B illustrates - to a curvature of the base strip 1 in the plane defined by the insertion direction E and the longitudinal direction L ( Fig. 8A , Deformation V1) and / or in the plane spanned by the transverse direction Q and the longitudinal direction L ( Fig. 8B , Deformation V2) can lead. Such curvatures on the base strip 1 are disadvantageous, in particular, when the base strip 1 is to be attached to a printed circuit board 3 and electrically connected to the printed circuit board 3. If a base strip 1, for example, with its base 10 are attached to a circuit board 3, which is in Fig. 8A If the base strip 1, however, in side mounting with a side wall 11, 12 are attached to the circuit board 3, the deformation V2 is according to Fig. 8B hindrance.

In contrast, in order to obtain an advantageous shrinkage behavior in the base strip 1 according to the present invention, the center of gravity M of the base strip 1 is arranged where the geometric center of gravity of the base strip 1 enveloping, imaginary geometric square B is located. The enveloping cuboid B in this case corresponds to the smallest possible geometric cuboid into which the base strip 1 fits. The enveloping cuboid touches the base strip 1 on its outer sides, as can be seen from the synopsis of Fig. 5 and Fig. 6 results.

The enveloping cuboid B has a geometric center of gravity M, corresponding to the center of gravity that results when the cuboid is assumed to be a solid body. This center of gravity M is also the center of gravity M of the base bar 1. This results in a balance-symmetrical distribution of material on the base 1 around the focus M around, which - was empirically determined - to an advantageous shrinkage behavior in the production of the base 1 with only slight deformations the bottom bar 1 leads.

The base strip 1 is thus constructed and designed in its sections that just a center of gravity M results, which corresponds to the center of gravity M of the enveloping cuboid B. Such a construction may be performed using appropriate design software tools, e.g. CAD tools are created.

To influence the material distribution of the base strip 1, for example, one of the side wall 11, 12 or both side walls 11, 12 have a (slightly) conical shape. Thus, the thickness of a side wall 11, 12 starting from the base 10, for example, opposite to the insertion direction E thicken outwardly, the conicity may for example be in the range of 0.5 ° to 2 °, for example, at 1 °.

Because the base strip 1 has advantageous shrinkage properties, comparatively small deformations on the base strip 1 result after manufacture due to shrinkage effects. This has the effect that the base strip 1 can be applied advantageously to a printed circuit board 3, for example in the context of automated assembly, and contact elements 14, which are attached to the receiving openings 103 on the base 10 of the base strip 1, via suitable soldering methods, for example the so-called Reflow soldering, can be contacted in a reliable manner with the circuit board 3 electrically.

The base strip 1 can with different contact elements 14, as in Figs. 7A and 7B is shown used.

Thus, pin-shaped, rectilinear contact elements 14 can be attached to the receiving openings 103, as shown in FIG Fig. 7A is shown. Such contact elements 14 extend with a first portion 140 into the receiving space 13 of the base strip 1 and are in the insertion direction E via the base 10 to the outside. With such contact elements 14, the base strip 1 can be attached via the base 10 to an associated printed circuit board 3, in order to be brought into engagement with associated contact openings on the printed circuit board 3 and soldered to the printed circuit board 3 to be connected.

Alternatively, however, angled contact elements 14 can be used, as in Fig. 7B are shown. These contact elements 14 protrude with a first portion 140 into the receiving space 13 of the base strip 1, extending with an angled portion 141 outside of the receiving space 13 along the Outside 101 of the base 10 between two associated transverse webs 104, 105 and project beyond one of the side walls 11, 12 to the outside, so that the base strip 1 with this side wall 11, 12 attached to a circuit board 3 and thus lying connected to the circuit board 3 can be.

Because an advantageous shrinkage behavior sets in the base strip 1, deformations are both in the plane defined by the plug-in direction E and the longitudinal direction L ( Fig. 8A ) as well as in the plane defined by the transverse direction Q and the longitudinal direction L ( Fig. 8B ) reduced. The base strip 1 can thus be used optionally with its base 10 or with one of its side walls 11, 12 to a circuit board 3, without this being hindered by an (excessive) curvature. A single design of a base strip 1 can thus be used for a top assembly (via the base 10) or for side mounting (via one of the side walls 11, 12), which the manufacturing and storage costs (otherwise for the production and storage of different types of Baseboards required) can significantly reduce.

The idea underlying the invention is not limited to the embodiments described above, but can in principle also be realized in a completely different kind of way.

A base strip of the type described here is advantageously designed as a high-pole base strip and therefore has, for example, more than twelve receiving openings for contact elements. In principle, however, it is conceivable to form a low-pole base strip in the manner described here.

A baseboard of the type described here can be advantageously made of the plastic LCP. In principle, however, a base strip can also be made of other materials, in particular other plastic materials.

LIST OF REFERENCE NUMBERS

1

base strip

10

Base

100

ground

101

outside

102

cathedral

103

opening

104, 105

crosspiece

11

sidewall

110

side surface

111

head edge

112

guide web

113

engaging members

12

sidewall

120

side surface

121

header

13

accommodation space

14

contact element

140, 141

section

2

plug elements

20

management

3

circuit board

B

Enveloping cuboid

e

insertion

L

longitudinal direction

M

Focus

Q

transversely

S

slot

V1, V2

deformation

Claims (12)

1. Base strip (1) for connection to a printed circuit board (3), comprising

   - a first side wall (11) which extends longitudinally along a longitudinal direction (L),

   - a second side wall (12) which extends longitudinally along the longitudinal direction (L) and is at a distance from the first side wall (11) along a transverse direction (Q) which is directed transversely in relation to the longitudinal direction (L), so that a receiving space (13) is formed between the side walls (11, 12), it being possible for one or more plug elements (2) to be inserted into the said receiving space in an insertion direction (E), and

   - a base (10) which connects the first side wall (11) and the second side wall (12) to one another and has a plurality of receiving openings (103) for receiving electrical contact elements (14),

   characterized
   in that the base strip is manufactured in one piece from plastic, and in that the centre of gravity (M) of the base strip (1) corresponds to the geometric centre of gravity of an imaginary cuboid (B) which envelops the base strip.
2. Base strip (1) according to Claim 1, characterized in that the insertion direction (E) is directed perpendicularly in relation to the longitudinal direction (L) and perpendicularly in relation to the transverse direction (Q).
3. Base strip (1) according to Claim 1 or 2, characterized in that a plurality of guide webs (112) which extend along the insertion direction (E), project into the receiving space (13) and are spaced apart in relation to one another along the longitudinal direction are arranged on the first side wall (11).
4. Base strip (1) according to Claim 3, characterized in that two guide webs (112), as viewed in the longitudinal direction (L), define between them an insertion slot (S1) into which a plug element (2) can be inserted in the insertion direction (E).
5. Base strip (1) according to Claim 3 or 4, characterized in that the first side wall (11), by way of a top edge (111), protrudes beyond the guide webs (112) against the insertion direction (E) on a side which is averted from the base (10).
6. Base strip (1) according to one of the preceding claims, characterized in that the first side wall (11), by way of a side face (110), extends flat along the longitudinal direction (L).
7. Base strip (1) according to one of the preceding claims, characterized in that the base (11), on an inner side which faces the receiving space (13), has a floor (100) which is of flat design.
8. Base strip (1) according to Claim 7, characterized in that a plurality of domes (102) protrude from the floor (100) into the receiving space (13), wherein a receiving opening (103) for a contact element (14) is arranged on each dome (102).
9. Base strip (1) according to one of the preceding claims, characterized in that the base (10), on an outer side (101) which is averted from the receiving space (13), is fitted with a plurality of transverse webs (104, 105) which extend along the transverse direction (Q), wherein a receiving opening (103) is arranged between two transverse webs (104, 105).
10. Base strip (1) according to Claim 9, characterized in that the transverse webs (104, 105), as viewed along the transverse direction (Q), extend beyond the total width of the base (10).
11. Base strip (1) according to one of the preceding claims, characterized in that the base strip (1) is produced from a liquid-crystalline polymer.
12. Base strip (1) according to one of the preceding claims, characterized in that the base strip (1) has twelve or more receiving openings (103).

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