DE102012216956A1 - Lead frame for lighting device e.g. LED module, has fitting station for semiconductor light source that is arranged adjacent to contact surface of conductive paths that are non-destructive pivotable towards connecting portions - Google Patents

Abstract

The lead frame (11) has several conductive paths (15,17) whose end is connected with a contact surface (13) for a semiconductor light source (14) that is connected with a connecting portion of conductive paths. A fitting station (16) for semiconductor light source is arranged adjacent to contact surface of conductive paths. The contact surfaces of the conductive paths are non-destructive pivotable towards the connecting portions. An independent claim is included for a method for manufacturing lead frame.

Description

The invention relates to a leadframe for a lighting device. The invention also relates to a lighting device, comprising at least one leadframe. The invention further relates to a method for producing a leadframe. The invention is particularly applicable to LED modules and LED lamps.

So far, semiconductor light sources are attached to a precisely designed for a lighting device leadframe. In this case, a passage width of the placement machine specifies a maximum placement width.

It is the object of the present invention to at least partially overcome the disadvantages of the prior art and in particular to provide a leadframe with a wider array of semiconductor light sources.

This object is achieved according to the features of the independent claims. Preferred embodiments are in particular the dependent claims.

The object is achieved by a leadframe for a lighting device, comprising a plurality of conductor tracks, which have a contact surface for a semiconductor light source end, which contact surface is connected to a connecting portion of this conductor, wherein a Bestückplatz for a semiconductor light source is formed by adjacent arranged contact surfaces of at least two conductor tracks and the contact surfaces of the conductor tracks are non-destructively pivotable against their connecting sections.

The interconnects thus form a conductor track structure or a conductor track frame, just the so-called "leadframe". The fact that the contact surfaces or contact field against the associated connecting portions are non-destructively pivotable (for example, by elastic, elastic-plastic or plastic deformation), the lead frame can be stretched (pulled apart or compressed), without being destroyed. In this case, the placement places are not deformed, so that attachment of a semiconductor light source is not impaired. The stretching makes it possible to adapt the leadframe to different lengths or widths of lighting devices without having to produce different leadframes.

The printed conductors may have a contact surface on one or both end sides or end regions. If the conductor track has a contact surface on both end sides, it can be used in particular for connecting adjacent placement locations. The two contact surfaces are then connected to each other by the connecting portion. If the conductor track has a contact surface only on one end side, in particular its connection section can be used for external mechanical and / or electrical contacting or connection, in particular its free end.

Preferably, the at least one semiconductor light source comprises at least one light-emitting diode. If several LEDs are present, they can be lit in the same color or in different colors. A color can be monochrome (eg red, green, blue, etc.) or multichrome (eg, white). The light emitted by the at least one light-emitting diode can also be an infrared light (IR LED) or an ultraviolet light (UV LED). Several light emitting diodes can produce a mixed light; z. B. a white mixed light. The at least one light emitting diode may be equipped with at least one own and / or common optics for beam guidance, z. At least one Fresnel lens, collimator, and so on. Instead of or in addition to inorganic light emitting diodes, z. Based on InGaN or AlInGaP, organic LEDs (OLEDs, eg polymer OLEDs) can generally also be used. Alternatively, the at least one semiconductor light source z. B. have at least one diode laser.

The adjacently arranged contact surfaces of a placement space are thus arranged so close to one another that they are suitable for the mechanical and / or electrical contacting of an associated semiconductor light source. Adjacent contact surfaces of a (common) Bestückplatzes are particularly spatially and thus electrically separated from each other.

It is a development that the leadframe is a flat leadframe. This makes it particularly easy to apply to a support of a lighting device. This flat leadframe (without limiting the generality in a horizontal plane) can be stretched without vertical throwing.

It does not need to be electrically connected to all tracks. These interconnects can then still serve a mechanical connection and / or a dissipation of waste heat generated by the semiconductor light sources.

It is an embodiment that the placement slots are equipped with semiconductor light sources. The leadframe can therefore be stretched when the semiconductor light sources are already on the leadframe and possibly already wired there. Thus, a production is greatly facilitated. This is especially possible because the placement places do not warp when stretched. In particular, it is thus also possible to use a leadframe which has no substrate foil, since the conductor tracks can be held together at their contact surfaces by the semiconductor light sources.

Alternatively, the leadframe may have a stretchable substrate film on the underside.

It is a development that the semiconductor light source connected to all contact surfaces of their Bestückplatzes, z. B. glued, is to support a secure cohesion of the leadframe. However, the semiconductor light source does not need to contact each of the contact surfaces or the associated interconnects electrically, but may selectively contact only one to all contact surfaces or associated interconnects, preferably two contact surfaces of their placement space or associated interconnects.

Basically, a shape and / or size of the contact surfaces of a placement place may be the same or different.

The contacting of the semiconductor light source is preferably carried out to a contact surface of the associated Bestückplatzes, because the electrical contact is thus exposed to no deformation and / or tension.

The electrical contact can be effected, for example, by means of at least one electrical contact element, in particular by means of a bonding wire, which connects a contact region of the semiconductor light source to a contact surface or contact field of the placement site. The electrical contact may alternatively or additionally be effected by a flip-chip contacting of the semiconductor light source with one or more of the contact surfaces of the placement space.

The type of semiconductor light source is not limited and may be present, for example, as a chip, in particular, bare die. The chip may be a surface emitting chip, e.g. Example, a ThinGaN LED chip from Osram Semiconductors. The chip may also be a volume radiator, z. B. with sapphire support, which can also emit light from a side surface. It is a preferred development for increasing a luminous efficiency, in particular for the case of a volume emitter chip, that the chip is arranged on the placement site via a reflective layer. Several LED chips can be mounted on a common substrate ("submount"), which in turn is arranged at a placement place.

Alternatively, the semiconductor light source may be a packaged semiconductor light source. The packaged semiconductor light source may already be housed for assembly. Alternatively, first a placement space may be equipped with an empty housing and then the empty housing with a semiconductor chip, z. B. LED chip, be provided.

It is a further development that at least one semiconductor light source, in particular light-emitting diode, has at least one wavelength-converting phosphor (for example conversion LED).

It is still an embodiment that the placement places is formed in each case by adjacently arranged contact surfaces of four interconnects and the interconnects form diamond-shaped arrangements, at the corners are placement places. This embodiment allows a particularly high elongation at the same time simple production. The leadframe is therefore constructed in particular by diamond-shaped or diamond-shaped 'unit cells'. However, other square 'unit cells' can be used, for. B. one in which not all four sides or tracks are the same length and / or opposing tracks are not parallel to each other.

However, the leadframe is not limited to such and z. B. Bestückplätze from three or more than four contact surfaces. For example, in three contact surfaces, a triangular 'unit cell' may be used.

It is a development that the contact surfaces of a Bestückplatzes are arranged in a 2 × 2 matrix pattern. Thus, a simple assembly and electrical contact with existing semiconductor light sources, which often have a rectangular bearing surface, simplified.

It is yet another embodiment that the leadframe is connected at opposite longitudinal sides, each with a contact rail. By means of the contact rails, the leadframe can be stretched evenly in its width in a simple manner and, moreover, be electrically contacted in the case of an electrically conductive contact rail. The contact rails can therefore also be understood as guide elements.

The contact rails may in particular be linear, particularly preferably strip-shaped. The contact rails may each have a number of holes in order to better grip them, z. B. by a tool for moving (pulling apart or squeezing) of the contact rails. The contact rails may in particular consist of metal.

The contact rails can be connected to free contact surfaces of the conductor tracks, in particular by means of conductor tracks provided on both sides with contact surfaces. However, the contact rails can also be connected, in particular by means of interconnects provided with contact surfaces on one side, with free ends of connecting sections of the interconnects.

It is a further embodiment that a width of the connecting portion is reduced at its transition to a contact surface to at least 20%. This reduction in cross-section supports a non-destructive deformability of the connecting portion against a contact surface. In addition, such a deformation of the conductor is limited to the width reduced range. This width-reduced region can in particular be regarded as a mechanical "joint".

The transition may be in the form of, for example, a taper from the connecting portion to the contact surface.

It is a development that the connecting sections of at least some of the conductor tracks web-shaped, d. H. with constant width, are formed. However, the shape of the connecting portions is basically not limited. Thus, a connecting portion may also have a variable width, broadening, for example, towards the center bulging. The broadening has the advantage that this results in a particularly large thermal interface.

The tracks of a Bestückplatzes may be configured the same. Alternatively, at least two tracks of a Bestückplatzes may be formed differently, which allows an even more variable shape. Thus, at least two of these interconnects may differ with regard to a shape and / or size of the contact surface of this placement site and / or with respect to a shape and / or size of the connection section. For example, one connection section may be longer than the other.

It is still a development that the conductor is made of metal, in particular copper or "Alloy 42". Metal, and especially copper and "Alloy 42" have high electrical and thermal conductivity, and are also highly ductile, making them easy to bend non-destructively. For example, an extended contact area may allow for better thermal dissipation.

It is also a development that a thickness of the conductor track is between 0.1 mm and 1 mm.

It is still a development that a width of a connecting portion corresponds to approximately 0.5 to 5 times its thickness. In particular, this area allows sufficient mechanical stability with sufficient deformability.

It is also a development that a length of a conductor track is between 3 mm and 20 mm.

The object is also achieved by a lighting device having at least one stretched leadframe as described above. Such a lighting device has the same advantages as the leadframe and can also be configured in an analogous manner.

In particular, at least one stretched leadframe may be applied to a support of the lighting device. The carrier may in particular be an electrically insulating and / or good heat-conducting carrier.

The object is further achieved by a method for producing a leadframe as described above, wherein the method has at least the following steps: applying a layer of electrically conductive material to a substrate; Working out of the tracks from the layer; Equipping the placement sites with semiconductor light sources; Removing the substrate; and stretching the leadframe by a certain amount.

This method has the advantage that it can be produced inexpensively with established production processes and thus on an industrial scale. In particular, a leadframe with the same production width can only be adapted by stretching to different application widths.

It is a development that the application comprises a lamination. In particular, the layer may be a previously separately prepared film, in particular metal foil.

The substrate may be, for example, an adhesive film. The substrate may be, for example, a sawing film ("dicing tape"). The substrate may be removable by means of UV light, which has the advantage that no mechanical forces are exerted on the leadframe.

Alternatively, the substrate may also remain, that is, the step of removing the substrate may be omitted.

It is an embodiment that the working out includes punching. This is very easy, z. B. by means of a single punching die, feasible. In particular, the punching likes by a known punching from roll to roll, so be carried out in a quasi-endless process.

As an alternative to stamping, for example, laser ablation may be performed.

It is a further development that the substrate is not severed during punching, since otherwise the cohesion of the leadframe may possibly be endangered.

It is yet another refinement that the step of equipping is followed by a step of electrically contacting the semiconductor light source with at least one of the conductor tracks, in particular a contact area associated with the placement location. The contacting can therefore also be carried out separately from the equipping, for example by means of a wiring by bonding wires.

It is also an embodiment for producing a leadframe, which is connected to opposite longitudinal sides, each with a contact rail, that are moved to stretch the leadframe its contact rails.

As a result, a uniform elongation can be achieved in a simple manner.

It is a development that be prepared between the working out and equipping the placement for placement, z. B. already with an adhesive tape (eg., A so-called "The Attach") provided ("pre-taped" or "pregetaped"). This can already be carried out favorably by a manufacturer or supplier of the leadframe produced so far. The loading can then be carried out particularly easily by another manufacturer.

The above-described characteristics, features, and advantages of this invention, as well as the manner in which they will be achieved, will become clearer and more clearly understood in connection with the following schematic description of exemplary embodiments which will be described in detail in conjunction with the drawings. In this case, the same or equivalent elements may be provided with the same reference numerals for clarity.

1 shows in plan view a longitudinal section of a leadframe in its manufactured state;

2 shows in plan view the leadframe 1 in a state which is pulled apart in its width;

3 shows in plan view the leadframe 2 in an even further extended in its width condition;

4 shows as a sectional representation in side view as a step for producing the leadframe an application of a flat metal foil on a substrate;

5 shows in plan view as a further step for producing the leadframe a state after punching;

6 shows in plan view as a further step for producing the leadframe a state after a loading and contacting;

7 shows in plan view the finished lead frame, as it is pulled apart by means of a tool in the width;

8th shows in oblique view from above a quarter of a trace in the region of a contact surface;

9 shows a plan view of a section of a leadframe in the region of a Bestückplatzes in an unstretched state;

10 shows a plan view of a section of a leadframe in the region of a Bestückplatzes in an exploded in the width state;

11 shows in plan view a section of a leadframe in a region of a Bestückplatzes with differently shaped contact surfaces;

12 shows a plan view of a section of a leadframe of a Bestückplatzes with still differently shaped contact surfaces;

13 shows in plan view a section of a leadframe of a Bestückplatzes with differently shaped connecting sections; and

14 shows as a sectional view in side view of a section of a leadframe in the field of Bestückplatzes.

1 shows a plan view of a longitudinal section of a lying in a horizontal plane, flat leadframe 11 in his finished state.

The leadframe 11 has several tracks 12 made of copper or Alloy 42. The tracks 12 have a contact surface on both end sides 13 or contact field or contact area for a Semiconductor light source in the form of an LED 14 on which contact surface 13 with a connection section 15 this track 12 connected is. A dashed line indicated placement place 16 is formed by adjacently arranged contact surfaces 13 each of four tracks 12 educated. The placement space 16 corresponds to a 2 × 2 array of closely spaced but electrically isolated contact surfaces 13 , The LED 14 is with all contact surfaces 13 their placement space 16 mechanically connected, z. B. glued, and holds the contact surfaces 13 together. An LED 14 is here by means of bonding wires 21 with two diagonally opposite contact surfaces 13 their placement space 16 electrically connected.

The LED 14 May be sheathed or unheated. In an alternative embodiment, the LED likes 14 also by means of a flip-chip technique on the contact surfaces 13 fixed and electrically contacted. The LED 14 may be covered by a phosphor, e.g. As a phosphor sheet, a phosphor plate or a potting compound with phosphor and thus represent a conversion LED.

Some tracks 17 have only one end face a contact surface 13 on, and are with their free ends 18 their connecting sections 15 on contact rails 19 appropriate. The two contact rails 19 are elongated (strip-shaped), metallic rails, which are on long sides of the leadframe 11 are arranged in parallel. The contact rails 19 have a number of holes for improved handling 20 on.

The leadframe 11 can also be understood as a conductor track structure, which is essentially constructed of diamond-shaped unit cells E, whose conductor tracks 12 form diamond-shaped arrangements, at the corners of the placement places 16 are located.

2 shows in plan view the leadframe 11 out 1 in an exploded in its width extension B state, as indicated by the two lateral arrows. This will be the connecting sections 15 against their associated contact surfaces 13 swiveled plastically, and that non-destructive, ie here: without significant cracking and without demolishing. When stretching the leadframe 11 this remains flat without vertical Verwurf or flat in the horizontal plane.

3 shows in plan view the leadframe 11 out 2 in an even further exploded state. The leadframe 11 however, may also be compressed in width extension B.

4 shows as a sectional view in side view as a step to manufacture the leadframe 11 an application of a flat metal foil 22 made of copper or "Alloy 42" on a substrate 23 , in particular by lamination. A thickness d of the metal foil 22 is between 0.1 mm and 1 mm. The substrate 23 is a detachable by UV light sawing film ("dicing tape"). The metal foil 22 is next structured to the tracks 12 to elaborate or create.

5 shows in plan view as a further step for producing the leadframe 11 a state after structuring by punching. Here are the not further used in the following surfaces of the metal foil 22 not shown. By punching the tracks are 12 . 17 but these are not interconnected and would be without the substrate 23 fall apart. The substrate 23 is so thick that it is not severed when punching.

6 shows in plan view as a further step for producing the leadframe 11 a condition after loading and contacting. By fitting with the LED 14 , z. B. by means of a so-called. "The attach" are the contact surfaces 13 a placement place 16 from the LED 14 held together mechanically.

Next is the substrate 23 removed (not shown), z. B. by UV irradiation. As a result, punching residues are removed.

After that, the contact rails 19 attached (not shown).

7 shows in plan view the finished leadframe 11 how it is pulled apart by means of a tool W in the width extension B. To do this, hook the tool W into the holes 20 one. In a purely plastic deformation of the tracks 12 remains the shape of the leadframe 11 essentially unchanged.

8th shows in view obliquely above a quarter of a trace 12 in the area of a contact surface 13 with a part of a connection section 15 , The connecting section 15 has a plan view, that is horizontal, in the direction of the contact surface 13 Rejuvenating rejuvenation section 24 on. The taper thus occurs with respect to a longitudinal extent of the connecting portion 15 on. A width at the transition between the connecting section 15 and the contact surface 13 , which is the smallest width of the rejuvenation area 24 corresponds to at least 20% of a width of the remaining connection section 15 ,

This allows the connection section 15 against the contact surface 13 when stretching the leadframe 11 be swiveled non-destructively in a horizontal plane H, because the material in the rejuvenation area 24 plastically deformed, as well as enlarged in 9 and 10 shown. Since the rejuvenation area 24 does not change in thickness d, pivoting out of the horizontal plane H is far more difficult to practically impossible, allowing for deformation of the leadframe 11 in a vertical direction V is suppressed.

11 shows in plan view a section of a leadframe 11 in one area of a placement space 16 with differently shaped contact surfaces 26 , The contact surfaces 26 now each have a curved recess at one corner 27 on, making them a group of a placement place 16 form an inner round or oval neckline.

12 shows in plan view a section of a leadframe 11 in one area of a placement space 16 with still differently shaped contact surfaces 28 , The contact surfaces of the placement place 16 are here twice at obliquely opposite positions as contact surfaces 26 formed and twice at obliquely opposite positions than the contact surfaces 28 , The contact surfaces 28 are similar to the contact surfaces 16 with a recess 27 but extended to provide a larger area for heat dissipation.

13 shows a plan view of a section of a leadframe in the area of a Bestückplatzes 16 with differently shaped connecting sections. The two links on the left 13 have a connection section 15 with constant width (eg, from 0.5 to 5 times its thickness d) between on, the contact surface shown above right 13 a comparatively longer connecting section 29 and the contact surface shown at the bottom right 13 a comparatively broadened connecting section 30 ,

The leadframe can be subsequently applied to a support of a lighting device. 14 shows a section in side view of a section of the leadframe 11 in the area of a placement place 16 , The leadframe 11 is on a carrier 31 a lighting device 32 been set up. The lighting device 32 may be, for example, an LED module, an LED lamp or an LED light.

The, in particular stretched, leadframe 11 is in this case via an optionally electrically insulating, adhesive layer 33 with the carrier 31 connected.

Although the invention has been further illustrated and described in detail by the illustrated embodiments, the invention is not so limited and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

LIST OF REFERENCE NUMBERS

11

leadframe

12

conductor path

13

contact area

14

LED

15

connecting portion

16

fitting station

17

conductor path

18

free end

19

contact bar

20

hole

21

bonding wire

22

metal foil

23

substratum

24

tapered section

26

contact area

27

curved recess

28

contact area

29

connecting portion

30

connecting portion

31

carrier

32

lighting device

33

adhesive layer

B

width extension

d

thickness

e

unit cell

H

horizontal plane

V

vertical direction

W

Tool

Claims (10)

Lead frame ( 11 ) for a lighting device ( 32 ), comprising - a plurality of printed conductors ( 15 . 17 ), which end a contact surface ( 13 ; 26 . 28 ) for a semiconductor light source ( 14 ), which contact surface ( 13 ; 26 . 28 ) with a connecting section ( 15 ; 29 . 30 ) of this track ( 15 . 17 ), wherein - a placement space ( 16 ) for a semiconductor light source ( 14 ) by adjacently arranged contact surfaces ( 13 ; 26 . 28 ) of at least two tracks ( 15 . 17 ) and - the contact surfaces ( 13 ; 26 . 28 ) of the tracks ( 15 . 17 ) against their connecting sections ( 15 ; 29 . 30 ) are non-destructively pivotable. Lead frame ( 11 ) according to claim 1, wherein the placement places ( 16 ) with semiconductor light sources ( 14 ) are equipped. Lead frame ( 11 ) according to one of the preceding claims, wherein - the placement places ( 16 ) each by adjacently arranged contact surfaces ( 13 ; 26 . 28 ) of four tracks ( 15 . 17 ) and - the tracks ( 15 . 17 ) form diamond-shaped arrangements, at the corners of which the placement places ( 16 ) are located. Lead frame ( 11 ) according to one of the preceding claims, wherein the leadframe ( 11 ) on opposite longitudinal sides, each with a contact rail ( 119 ) connected is. Lead frame ( 11 ) according to one of the preceding claims, wherein a width of the connecting portion ( 15 ; 29 . 30 ) at its transition ( 24 ) to a contact surface ( 13 ; 26 . 28 ) is reduced to at least 20%. Lighting device ( 32 ), comprising at least one stretched leadframe ( 11 ) according to any one of the preceding claims. Method for producing a leadframe ( 11 ) according to one of the preceding claims, wherein the method comprises at least the following steps: - applying a layer ( 22 ) of electrically conductive material on a substrate ( 23 ); - Working out of the tracks ( 15 . 17 ) from the layer; - equipping the placement locations ( 16 ) with semiconductor light sources ( 14 ); Removing the substrate ( 23 ); - Stretching the leadframe ( 11 ) by a certain value. The method of claim 7, wherein the trimming comprises punching. Method according to one of claims 7 or 8, wherein the step of loading a step of electrically contacting the semiconductor light source ( 14 ) with at least one of the tracks ( 15 . 17 ). Method according to one of claims 7 or 8 for producing a leadframe ( 11 ) according to claim 4, wherein for stretching the leadframe ( 11 ) its contact rails ( 19 ) are moved.

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