EP3167224B1 - Semiconductor lamp - Google Patents

Description

The invention relates to a semiconductor lamp, comprising at least one semiconductor light source arranged on one side of a substrate and a driver circuit for driving the at least one semiconductor light source. The invention is particularly applicable to retrofit lamps, in particular incandescent or halogen lamp retrofit lamps.

There are retrofit lamps are known in which a driver board is housed in a front open driver cavity of a housing. The front is closed by means of serving as a heat sink metallic lid. A carrier ("LED carrier") equipped with light-emitting diodes ("LEDs") is mounted on an outside of the heat sink. The driver board and the LED carrier are thus designed as two separate components, which are electrically connected by means of various contacts (plug, solder, cable, etc.) through the heat sink. For current connection methods, there are hardly any simple or inexpensive methods for mechanically passing the electrical connection lines through the heat sink. Rather, this production step happens mostly by hand.

Another disadvantage is that the heat transfer from the LEDs to the heat sink is not effective by the intervening carrier. In order to improve the heat transfer, metal core boards are sometimes used as LED carrier, which are expensive. Alternatively, thin (e.g., 0.5 mm thick) FR4 boards can be used which also add cost and reduce thermal resistance from the LEDs to the heat sink only to a limited extent.

From the document WO 2010/032169 A1 is a semiconductor lamp with a printed circuit board with a thermally conductive portion and with a heat sink, which communicates with this section is known.

It is the object of the present invention to at least partially overcome the disadvantages of the prior art. It In particular, it is an object to provide a possibility for simplified electrical contacting of a driver circuit with associated semiconductor light sources, in particular LEDs, of a semiconductor lamp. It is still a specific object to provide a possibility for inexpensive heat dissipation of semiconductor light sources, in particular LEDs, a semiconductor lamp in a structurally simple and cost-effective manner.

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

The object is achieved by a semiconductor lamp comprising at least one semiconductor light source arranged on a first side (hereinafter referred to as "front side" without limitation of generality) of a substrate and a driver circuit for driving the at least one semiconductor light source, wherein at least a part of the driver circuit is connected to a semiconductor light source the second side facing away from the at least one semiconductor light source (hereinafter referred to as the "backside" without limitation of generality) of the substrate, a heat sink rests flat on the front side of the substrate, wherein the heat sink is followed by at least one optical element, which rearwardly projecting legs which extend through a respective recess in the bottom of the heat sink to the substrate. The fact that the driver circuit is no longer mounted on a separate from the substrate of the semiconductor light sources printed circuit board, the need for electrical connection of two carriers is eliminated, which significantly facilitates production. In addition, a reduction of components for the contacting (plug, cable, etc.) and thus a saving in the component costs can be achieved. In addition, a carrier is saved. The manufacturing process (eg a combination of wave soldering and SMD soldering) for such a populated substrate is comparable to manufacturing processes for all common two-sided boards and thus known, available and inexpensive. This in turn enables a saving of investment costs in special machines for eg laser soldering and / or a saving of manual workstations. In addition, the previous contacting of the driver board and the LED carrier is often a mechanical and manufacturing technical weakness and thus often a problem for quality assurance and achieving a long life. Since this contacting is no longer necessary in the present invention, the quality and the service life can be increased or a risk of failure can be minimized.

The driver circuit may comprise a plurality of electrical and / or electronic components in order to convert electrical signals fed into the socket into electrical signals suitable for the operation of the at least one semiconductor light source. Not all components of the driver circuit need be present on the back side, but some of the components may also be present on the front side, in particular small and / or flat components such as resistors, e.g. Thick film resistors. Large components such as integrated circuits, capacitors, coils, electronic switches, etc. are preferably attached only to the back of the substrate.

However, it is an advantageous embodiment for a low-lying and flat design of the front side that all components of the driver circuit are present on the rear side.

In particular, the at least one semiconductor light source comprises at least one light-emitting diode ("LED"). 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; eg a white mixed light. The at least one light-emitting diode can at least contain a wavelength-converting phosphor (conversion LED). The phosphor may alternatively or additionally be arranged remotely from the light-emitting diode ("remote phosphor"). The at least one light-emitting diode can be in the form of at least one individually housed light-emitting diode or in the form of at least one LED chip. Several LED chips can be mounted on a common substrate ("submount"). The at least one light emitting diode may be equipped with at least one own and / or common optics for beam guidance, for example at least one Fresnel lens, collimator, and so on. Instead of or in addition to inorganic light-emitting diodes, for example based on InGaN or AlInGaP, it is generally also possible to use organic LEDs (OLEDs, for example polymer OLEDs). Alternatively, the at least one semiconductor light source may, for example, comprise at least one diode laser.

The semiconductor lamp has, in particular at its rear end, a socket for the mechanical and electrical connection to a socket. The socket may be, for example, an Edison socket or a bipin socket. In particular, the back side of the substrate may face toward the socket (face back) and the front face away from the socket (face forwards).

Generally, "backward" or "backward" may refer to a direction or orientation toward the socket. By "front" or "forward" may analogously be understood a direction or orientation away from the pedestal. Also, "front" or "forward" may mean a direction or orientation to a light emitting area. It is a development that the semiconductor lamp has a longitudinal axis, which extends from a rear base area to a front Lichtabstrahlbereich. Then under "front" or "forward" an arrangement or orientation in the direction of the longitudinal axis and under "backwards" or "to the rear a Arrangement or orientation against the direction of the longitudinal axis to be understood.

The substrate may comprise any suitable electrically insulating base material, e.g. conventional base material for circuit boards such as FR4, other plastic or ceramic. Also, a metal core board may be used. The substrate may have a conductive structure (e.g., comprising at least one conductive trace and / or at least one contact patch) at its front side and / or at its back surface. Alternatively or additionally, components attached to the substrate may be attached by means of a bonding wire or the like. be electrically connected. However, other connection methods can be used. According to the invention, a heat sink lies flat on the front side of the substrate. This is now possible because the heat sink no longer needs to be provided as a partition between the driver board and the LED carrier. This refinement affords the advantage that the substrate on the side on which the semiconductor light sources are located is cooled by the heat sink, eliminates a thermal resistance through the substrate and binds the heat sink to the semiconductor light sources in a particularly effective manner. The improved cooling connection also allows for reduction of material (e.g., aluminum) in the lamp thereby optimizing costs. In addition, the improved cooling connection may increase the service life, enable the use of less expensive components and / or make dispensing with a potting material (see below) easier. However, in particular with only a low power of the at least one semiconductor light source, the heat sink may also be dispensed with.

The heat sink may for example consist of ceramic or metal, for example aluminum.

It is yet an embodiment that the heat sink has at least one recess for the at least one semiconductor light source, so that the light of the semiconductor light source (s) can pass through virtually unhindered. Also, the heat sink may have further recesses, e.g. for other components, solder points and / or for the implementation of structural components such as legs etc. The recesses generally allow a direct or with a very small gap connected support of the heat sink and thus a particularly low thermal resistance.

It is a further embodiment that the heat sink is a shell-like heat sink with a plate-shaped bottom and an edge thereof angled outgoing edge, wherein the at least one recess for the at least one semiconductor light source is introduced into the ground. Such a heat sink can be easily produced.

It is yet another embodiment that the heat sink is attached to the substrate by means of an adhesive heat-conducting layer, in particular adhered thereto. This allows a firm connection with only a very low thermal resistance. The adhesive thermal conductive layer may e.g. a TIM (Thermal Interface Material) film. The heat conducting layer may also consist of a thermal compound.

It is a development that the heat sink rests on a thermally good conductive gap filler on the front of the substrate. This may eliminate the need for recesses in the bottom (e.g., solder points) because the gap filler allows for a greater clearance between the heat sink and the front of the substrate. The gap filler has a significantly higher thermal conductivity than conventional substrate materials. He likes e.g. consist of thermal grease.

It is also an embodiment that the substrate is housed in a housing. This allows a Touch resistance and protection against mechanical and chemical stress.

The substrate may be non-positively fixed (e.g., by means of a press fit or interference fit) in the housing, positively and / or cohesively (e.g., by adhesive). It may be e.g. rest on the inside of the housing existing retaining tabs or on a stage of the housing.

The housing consists in particular of an electrically insulating material, in particular plastic. The housing may be formed in one or more parts.

The housing may in particular have a rearward base region, which together with at least one electrical contact element can form a base of the semiconductor lamp. The socket may be, for example, an Edison socket or a bipin socket.

It is also an embodiment that the housing is open on the front side. This allows use of components of the semiconductor lamp. In addition, a joining direction is determined, which keeps manufacturing complexity at a low level.

It is also an embodiment that the side edge of the heat sink rests flat against an inner side of the housing. This enables effective heat dissipation on and through the housing as well as a secure fit in the housing, for example in a tight fit. For this purpose, the side edge may be inserted in particular between retaining tabs and a rigid housing wall, for example, be trapped. The retaining tabs may wear the substrate on the upper side. The side edge extends in particular to the rear. It may have one or more interruptions to provide elastic deformability.

It is also an embodiment that the driver circuit is surrounded in the housing by potting material. This improves heat dissipation to the housing since potting material has lower thermal resistance than air. In addition, the driver circuit (and any lines therefrom, e.g., to the socket) is so specially protected, e.g. against mechanical stress. The potting material may be filled, for example, after the insertion of the loaded substrate into the housing. It is preferably filled to a maximum height of the substrate in order not to damage or cover the LED chips.

It is yet an embodiment that the substrate has a line structuring on only one side and components attached to the other side of the substrate are electrically connected to the line structuring via electrically conductive feedthroughs through the substrate. Such a substrate is particularly inexpensive. Alternatively, a substrate provided with a conductive structure on both sides may be used.

The electrically conductive passage may be an independent implementation, for example in the form of at least one via or at least one vias (Vertical Interconnect Access). A conductive feedthrough may additionally or alternatively be a pin of a through-hole technology (THT, or pin-in-hole technology, PIH) component, eg, an electrical or electronic device Driver circuit, be formed. The components of the driver circuit may therefore be in particular THT components whose pins or connecting pins are passed through the substrate, for example, and are electrically connected to the front, for example soldered there. Alternatively or additionally, for example, at least one component may be electrically connected to a via at the rear, for example an SMD component may be soldered to a via. According to the invention, the heat sink is followed by at least one optical element having rearwardly projecting legs or feet extending through a respective recess in the bottom of the heat sink to the substrate. The legs easily enable accurate positioning of the optical element with respect to the at least one semiconductor light source. They may serve as spacers, for example. The recesses may serve as alignment aids and as lateral guides.

It is also an embodiment that the semiconductor lamp is a retrofit lamp. Such may be used instead of a conventional lamp without semiconductor light sources and therefore has in particular a base for connection to a conventional socket. The retrofit lamp may e.g. an incandescent retrofit lamp, e.g. with an Edison base, e.g. Type E14 or E27. It may also be a halogen lamp retrofit lamp, e.g. with a bipin socket, e.g. of the type GU, e.g. GU10 or GU5.3.

Fig.1

zeigt als Explosionsdarstellung in Schrägansicht eine Halbleiterlampe gemäß einem ersten Ausführungsbeispiel;

Fig.2

zeigt als Explosionsdarstellung in Schrägansicht ausgewählte Teile der Halbleiterlampe gemäß dem ersten Ausführungsbeispiel;

Fig.3

zeigt als teilweise Schnittdarstellung in Schrägansicht die zusammengebaute Halbleiterlampe gemäß dem ersten Ausführungsbeispiel; und

Fig.4

zeigt als teilweise Schnittdarstellung in Schrägansicht einen Ausschnitt aus der Halbleiterlampe gemäß dem ersten Ausführungsbeispiel.

The above-described characteristics, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more clearly understood in connection with the following schematic description of an embodiment 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.

Fig.1

shows an exploded view in an oblique view of a semiconductor lamp according to a first embodiment;

Fig.2

shows an exploded view in an oblique view selected parts of the semiconductor lamp according to the first embodiment;

Figure 3

shows as a partial sectional view in an oblique view of the assembled semiconductor lamp according to the first embodiment; and

Figure 4

shows as a partial sectional view in an oblique view a section of the semiconductor lamp according to the first embodiment.

Fig.1 shows an exploded view in an oblique view of a semiconductor lamp 1 in the form of a halogen retrofit lamp. The semiconductor lamp 1 has a housing 2 with a cup-like basic shape, which has a base region 3 at its rear end. The housing 2 is shown here partially cut away. The semiconductor lamp 1 has a longitudinal axis A extending from the rear (the base region 3) to the front (a light emission region).

The base region 3 is used for mechanical attachment of the semiconductor lamp 1 in a conventional bipin socket (not shown), e.g. for halogen lamps. For further mechanical fastening and for electrical connection of the semiconductor lamp 1, two metallic pins 4 protrude rearward from a rear end face of the base area 3, which together with the base area 3 form a biped base of the semiconductor lamp 1, for example of the "GU" type, e.g. GU10.

The housing 2 is open at the front, wherein a substrate 6 can be inserted through a front opening 5. The substrate 6 is here designed as a circular disk-shaped FR4 or CEM substrate, as also more precisely in FIG Fig.2 shown. At a front side 7 of the substrate 6, a plurality of semiconductor light sources in the form of LED chips 8 are arranged. The LED chips 8 are connected to one another via contact fields 9 present on the front side 7. The contact fields 9 consist of metallic layers, for example of copper, and together form a line structure.

On a rear side 10 of the substrate 6, components 11 of a driver circuit for driving the LED chips 8 are attached. The substrate 6 is therefore a common substrate both for the LED chips 8 and for the components 11 of the driver circuit. The front 6 and the back 10 of the substrate 6 are basically electrically isolated from each other. An electrical connection of the components 11 of the driver circuit and the LED chips 8 is achieved by at least one electrically conductive passage (not shown) between the front 6 and the back 10 of the substrate 6.

It is a variant that the substrate 6 is provided on both sides with a respective line structure, which may each have one or more conductor tracks and / or contact pads. The line structure here has four contact fields 9, which interconnect the spatially annularly arranged LED chips 8 electrically in series. It is a particularly inexpensive variant that the substrate 6 only one-sided, e.g. here at the front 7, is provided with a respective line structure. An electrical connection of the components 11 of the back 10 may then be e.g. be implemented by means of the conductive bushing (s) with the line structure of the front side 7. This may be e.g. be done by the fact that the components 11 are configured as through-mounted components, for example by having guided through the substrate 6 pins (o. Fig.) Have.

On the front side 7 of the substrate 6 is a heat sink 12 with a shell-like basic shape on the surface, in more detail in Fig.2 is shown. The heat sink 12 has a plate-shaped bottom 13 and one of the edge side to the rear outgoing, multi-perforated side edge 14. The bottom 13 has recesses 15 for the LED chips 8 and further recesses 16, for example, for projections produced by conductive bushings on the front side 7 of the substrate 6. In addition, 13 recesses 23 in the bottom for legs 22 available, as will be explained in more detail below.

The heat sink 12 is adhered to the substrate 6 by means of an adhesive heat-conducting layer 17. This allows a strong attachment with low thermal resistance. The heat conducting layer 17 has analogous holes or recesses 15a, 16a and 23a to the recesses 15, 16 and 23 of the bottom 13, as well as in more detail Fig.2 shown. The heat-conducting layer 17 may, for example, be present as a heat-conducting foil. As an alternative to a TIM material, it is also possible to use a so-called "gap filler", for example a so-called "gap pad", so that recesses 16a for projections produced by conductive feedthroughs can be dispensed with without too much heat resistance ,

In order to improve a mechanical and thermal connection of the components 11 to the housing 2, the housing 2 is filled to the substrate 6 with a potting material 20, which thus surrounds the components 11.

The heat sink 12 is covered on the front by an optical element in the form of a lens element 21. The lens element 21 is a common optic for the LED chips 8 and has on the back several (here: three) projecting support areas in the form of pin-shaped feet or legs 22, as well as in more detail Fig.2 shown. The legs 22 pass through recesses 23 in the bottom 13 of the heat sink 12 and analog recesses 23a in the heat conducting layer 17. They contact the front 7 of the substrate 6 and thus act as a positioning aid, in particular as a spacer.

The lens element 21 is pressed by means of a retaining ring 24 in a rearward direction, so that it does not detach from the substrate 6. The retaining ring 24 is arranged in front of the lens element 21 and can be latched to an inner side of the housing 2 via latching hooks 25.

Figure 3 shows the assembled semiconductor lamp 1 with a side cut housing. 2 Figure 4 shows the assembled semiconductor lamp 1 as a sectional view through a front region at the level of the substrate 6. The potting material 20 is not shown in these two figures.

The side edge 14 of the heat sink 12 lies with its outer surface on the housing 2 and thus enables effective heat transfer to the housing 2. In addition, the heat sink 12 may be held so clamped in the housing 2.

The substrate 6 rests with an edge region of its rear side 10 on retaining tabs 26, which protrude from an inner side of the housing 2 to the front.

The retaining ring 24 closes the front practically flush with the housing 2 from.

The lens element 21 has above each LED chip 8 on a rearwardly projecting lens-like light-collecting region 27. The light-collecting region 27 may, for example, have a return with a convex bottom over a respective LED chip 8. As a result, virtually all of the light emitted by an LED chip 8 is collected and guided in the lens element 21 over a wide area to the front. At its fundamentally flat front side, the lens element 21 has a field 28 of microlenses, which further uniforms the light emission. The microlenses may in particular be convex, e.g. spherical, aspherical or pillow-shaped.

This semiconductor lamp 1 has only one joining direction, which keeps the manufacturing complexity of the entire platform at a low level.

During operation of the semiconductor lamp 1, the driver circuit is connected via the electrical connection pins 4 Driver components 11 with an electrical supply signal (eg a mains voltage) supplied. The driver circuit converts the electrical supply signal into an electrical operating signal suitable for operating the series-connected LED chips 8. This may for example be clocked and / or be adjustable in terms of its current level. The operating signal may allow for dimmed operation of the LED chips 8. The at least some of the pins of the driver components 11 of the driver circuit are passed through the substrate 6 and are electrically connected to the local contact pads 9, the operating signal can be easily fed into the LED chips 8. The light then emitted from the LED chips 8 passes through the recesses 15 of the bottom 13 of the heat sink 12 and into respective light collecting regions 27 of the lens element 21. The light injected rearwardly into the lens element 21 is subsequently transmitted through the array 28 of microlenses at the front the semiconductor lamp 1 emitted. Waste heat generated by the LED chips 8 is transferred to the bottom 13 of the heat sink 12 and, in the following, mainly emitted from its side wall 14 onto the housing 2 and through the housing 2 to the outside.

While the invention has been further illustrated and described in detail by the illustrated embodiment, 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.

Generally, "on", "an", etc. may be taken to mean a singular or a plurality, in particular in the sense of "at least one" or "one or more" etc., unless this is explicitly excluded, e.g. by the expression "exactly one", etc.

Also, a number may include exactly the specified number as well as a usual tolerance range, as long as this is not explicitly excluded.

reference numeral

1

Semiconductor lamp

2

casing

3

plinth

4

pin

5

Front opening

6

substratum

7

front

8th

LED chip

9

Contact field

10

back

11

module

12

heatsink

13

ground

14

margin

15

recess

15a

recess

16

recess

16a

recess

17

heat conducting

20

potting

21

lens element

22

foothold

23

recess

23a

recess

24

retaining ring

25

latch hook

26

retaining tab

27

Light collection area

28

Field of microlenses

A

longitudinal axis

Claims (10)

1. A semiconductor lamp (1) comprising

   - at least one semiconductor light source (8) arranged on a front side (7) of a substrate (6) and

   - a driver circuit (11) for driving the at least one semiconductor light source (8),
   whereby

   - at least a part of the driver circuit (11) is mounted on one of the rear sides (10) of the substrate (6) facing away from the at least one semiconductor light source (8),

   wherein a heat sink (12) rests flat on the front (7) of the substrate (6),
   characterized in that at least one optical element (21) is connected downstream of the heat sink (12), which has rearwardly projecting support legs (22) which extend through a respective recess (23) in the base (13) of the heat sink (12) to the substrate (6).
2. Semiconductor lamp (1) according to claim 1, wherein the heat sink (12) has at least one cutout (15) for the at least one semiconductor light source (8).
3. Semiconductor lamp (1) according to one of the preceding claims, wherein the heat sink (12) is a cup-like heat sink (12) having a plate-shaped base (13) and a lateral edge (14) angled therefrom, wherein the at least one cutout (15) for the at least one semiconductor light source (8) is provided in the base (13) .
4. Semiconductor lamp (1) according to any of Claims 1 to 3, wherein the heat sink (12) is attached to the substrate (6) by means of an adhesive heat conducting layer (17) .
5. Semiconductor lamp (1) according to any of the preceding claims, wherein the substrate (6) is located in a housing (2).
6. Semiconductor lamp (1) according to claim 5, the housing (2) having a rear socket region (3) and being open at the front.
7. Semiconductor lamp (1) according to one of claims 3 or 4 in combination with one of claims 5 or 6, the lateral edge (14) of the heat sink (12) resting flat on an inside of the housing (2).
8. Semiconductor lamp (1) according to any of claims 5 to 7, wherein the driver circuit (11) is surrounded in the housing (2) by potting material (20).
9. Semiconductor lamp (1) according to one of the preceding claims, wherein the substrate has a conductor structure (9) only on one side (7) and components (11) fastened to the other side (10) of the substrate (6) are electrically connected to the conductor structure (9) via electrically conductive leadthroughs through the substrate (6).
10. Semiconductor lamp (1) according to any of the preceding claims, wherein the semiconductor lamp (1) is a retrofit lamp.

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