Connection carrier, method for producing a soldered joint, and component

Abstract

The invention describes a connection carrier (1) having a main body (2) with a metallization (3), wherein a solder resist layer (4) is applied to the metallization (3) at least at points, and the solder resist layer (4) has a thickness of at most 5 micrometres. The invention also describes a method for producing a soldered joint (12), and a component, in particular having a micro-LED.

Description

[0001] Description

[0002] Connection carrier, method for producing a solder connection and component

[0003] A connection carrier, a method for producing a solder connection and a component are specified.

[0004] One object is to provide a connection carrier that enables the effective production of a solder connection to an electronic component. Furthermore, a simple and effective method for producing a solder connection and a component are to be described.

[0005] According to at least one embodiment, the connection carrier has a base body with a metallization. The base body serves in particular for the mechanical stabilization of components arranged therein or on it. The base body is, for example, rigid or mechanically flexible. In particular, the base body is opaque to visible light. Alternatively, the base body can be transparent to visible light, IR radiation and / or UV radiation. For example, the base body then has a transparency of at least 90% or at least 95% for visible light, IR radiation and / or UV radiation incident on it. For example, the base body comprises a plastic or is formed from it.

[0006] A transparent base body advantageously makes it possible for the connection carrier, and thus also a component that includes the connection carrier, to appear transparent to a human observer. This allows the connection carrier to be used, for example, for backlighting applications, such as in displays.

[0007] In particular, metallization involves conductor tracks. The metallization is applied, for example, to the base body. The metallization can be used for electrical contacting of components arranged on the connection carrier.

[0008] According to at least one embodiment of the connection carrier, a solder resist layer is applied to the metallization at least in places. In particular, the solder resist layer completely covers the metallization at locations where the metallization is not covered by material of the base body. For example, the solder resist layer is in direct contact with the metallization. In particular, the solder resist layer is electrically insulating.

[0009] The solder resist layer is particularly designed to prevent liquefied solder material from flowing. In other words, the solder resist layer has a de-wetting effect on liquefied solder material. In particular, the liquefied solder material does not spread on the solder resist layer. Spreading, here and in the following, refers to the spreading of a liquid, such as the liquefied solder material, on a surface in the form of a flat film. During spreading, a macroscopic contact angle of 0° can be observed, in particular.

[0010] For example, the solder resist layer is patternable. In other words, the solder resist layer can be applied to the metallization in a patterned manner or, in particular, can be patterned by photostructuring. For example, the solder resist layer comprises an organic material such as a spray paint. Alternatively, the solder resist layer can be formed with an inorganic material, for example, a metal nitride.

[0011] According to at least one embodiment of the connection carrier, the solder resist layer has a thickness of at most 5 micrometers, in particular of at most 3 micrometers. The solder resist layer can have a thickness of at least 0.2 micrometers or of at least one micrometer. The thickness is determined, for example, in a vertical direction that runs perpendicular to a main extension direction of the connection carrier.

[0012] According to at least one embodiment, the connection carrier comprises the base body with the metallization, wherein the solder resist layer is applied to the metallization at least in places, and the solder resist layer has a thickness of at most 5 micrometers. In particular, the connection carrier is a printed circuit board (PCB).

[0013] With other connection carriers, the solder resist layer can, for example, have a thickness in the range of 30 micrometers to 40 micrometers. This can mean that a solder paste that is only intended to be applied to small areas with an extension of a maximum of 100 micrometers, in particular a maximum of 50 micrometers, for example a maximum of 20 micrometers, no longer adheres to the connection carrier. In this case, the solder resist layer is significantly thinner than with the other connection carriers. Therefore, the solder paste adheres to the connection carrier even when applied to the small areas. This advantageously means that even components with an extension in the micrometer range can be effectively connected to the connection carrier.

[0014] As an alternative to using a solder resist layer, a laser resist is also used in other connection carriers. With a laser resist, a well-wettable gold layer is partially removed with the help of a laser and an underlying nickel layer is exposed. The nickel layer oxidizes, for example, due to environmental influences and has a de-wetting effect. The solder material therefore flows less on the nickel layer and the solder connection can be created in small areas. However, using a laser resist can damage the base body and result in aging problems. Using the solder resist layer described here, damage to the base body and the resulting aging problems are advantageously avoided.

[0015] According to at least one embodiment of the connection carrier, the solder resist layer comprises or consists of copper(I) nitride (CuAn). Advantageously, copper(I) nitride makes it possible to form a thin solder resist layer. In addition, copper(I) nitride is characterized in particular by the fact that it has a dewetting effect on liquefied solder material. The copper(I) nitride can also serve as corrosion protection for the underlying metallization. According to at least one embodiment of the connection carrier, the solder resist layer has a thickness of at most 100 nanometers, in particular at most 50 nanometers, for example in the range between 15 nanometers and 30 nanometers inclusive. In particular, such a thickness is achieved using a metal nitride, for example copper(I) nitride, as the material for the solder resist layer.

[0016] According to at least one embodiment of the connection carrier, the metallization comprises or consists of copper. A metallization made of or with copper can advantageously be easily applied to the base body. For example, the metallization comprising or consisting of copper is applied to the base body by printing.

[0017] According to at least one embodiment of the connection carrier, the metallization comprises a nickel layer and / or a gold layer. In particular, the metallization comprises a layer stack of the following materials: copper, nickel, gold. For example, the materials are arranged in the specified order, with the copper being in direct contact with the base body of the connection carrier. Advantageously, a solder connection can be effectively created using a metallization with a nickel layer and / or a gold layer.

[0018] According to at least one embodiment of the connection carrier, the metallization has at least two regions. The two regions are electrically insulated from one another, in particular by a recess. Advantageously, an electrical component can thus be electrically connected via the two regions of the metallization. For example, the two regions of the metallization are two conductor tracks that are electrically insulated from one another.

[0019] According to at least one embodiment of the connection carrier, the solder resist layer in the recess is in direct contact with the base body. In particular, the solder resist layer is applied to the base body between the at least two regions of the metallization. For example, the solder resist layer completely covers one side of the connection carrier. In other words, in this embodiment, both the metallization and regions of the base body that are not covered by the metallization are covered by the solder resist layer.

[0020] According to at least one embodiment of the connection carrier, the metallization on a side facing away from the base body in the region of the recess is free of the solder resist layer. In other words, the solder resist layer does not completely cover the metallization. For example, the metallization is free of the solder resist layer in regions intended for connecting an electrical component. Advantageously, a solder connection of a defined size can be created in the regions of the metallization that are free of the solder resist layer, because the solder resist layer prevents, in particular, the spreading of liquefied solder material.

[0021] Furthermore, a method for producing a soldered connection is described. In particular, the connection carrier described here is suitable for use in the method for producing a soldered connection. Embodiments, features, and advantages described in connection with the connection carrier therefore also apply to the method, and vice versa.

[0022] According to at least one embodiment of the method, a connection carrier comprising a base body with a metallization is provided. A solder resist layer is applied to the metallization at least in places. The solder resist layer has a thickness of at most 5 micrometers.

[0023] According to at least one embodiment of the method, a solder paste is applied next to or on the solder resist layer. In particular, the solder paste is applied to areas of the connection carrier that are subsequently intended to contact and / or attach an electrical component. For example, the solder paste comprises a solder material.

[0024] According to at least one embodiment of the method, the solder paste is at least partially melted. In particular, the solder material in the solder paste is melted. It is also possible for other components of the solder paste to be melted.

[0025] According to at least one embodiment of the method, an electronic component is applied. In particular, the electronic component is applied before or after the at least partial melting of the solder joint. The electronic component is applied, for example, such that it is in direct contact with the solder paste or with the at least partially melted solder paste.

[0026] According to at least one embodiment of the method, the solder connection is formed. In particular, the solder connection between the connection carrier and the electronic component is formed by the solidification of the solder material. The solder connection enables, for example, a material-to-material, electrically conductive connection between the connection carrier and the electronic component.

[0027] According to at least one embodiment, the method for producing a solder connection comprises the following steps:

[0028] - Providing the connection carrier comprising the base body with the metallization, wherein the solder stop layer is applied to the metallization at least in places, and the solder stop layer has a thickness of at most 5 micrometers,

[0029] - Applying the solder paste next to or on the solder resist layer,

[0030] - Application of the electronic component,

[0031] - at least partial melting of the solder paste, and

[0032] - Forming the solder connection.

[0033] In particular, the steps are performed in the specified order. However, it is also possible that the steps of applying the electronic component and at least partially melting the solder paste are swapped.

[0034] Advantageously, the solder resist layer prevents the solder material of the solder paste from flowing or spreading across the connection carrier during the process. This makes it possible to produce a solder connection with a defined size. The solder connection produced can therefore advantageously have a greater thickness than solder connections produced on a different connection carrier. For example, the solder connection produced using the process described here is twice as high as a solder connection on a different connection carrier. A thicker solder connection is, for example, more reliable.

[0035] According to at least one embodiment of the method, a stencil, for example made of a metal, is used to apply the solder paste. In particular, the solder paste is printed with the aid of the stencil. The stencil advantageously enables selective application of the solder paste to predetermined areas. Because the solder resist layer has a maximum thickness of 5 micrometers, it is possible to apply the solder paste even to small areas, i.e., areas with an extension in the micrometer range.

[0036] According to at least one embodiment of the method, the solder paste comprises a solder material formed with at least one element from the group consisting of Sn, Pb, Bi, Sb, Ag, Cu, and Au. In particular, the solder material is selected from the following group: Sn, SnAgCu, SnAu, SnAg, SnSb, SnPb, SnBi, and mixtures thereof.

[0037] According to at least one embodiment of the method, the solder paste comprises a flux. The flux, in particular through its ingredients, cleans and / or activates a surface to be soldered. In this case, the flux can have a reducing effect. In particular, the flux comprises a material selected from the following group: succinic acid, formic acid, hydrochloric acid, adipic acid, phosphoric acid, salts, and mixtures thereof. Zinc chloride and / or ammonium chloride, for example, are used as salts.

[0038] According to at least one embodiment of the method, the solder resist layer comprises or consists of copper(I) nitride. The solder paste further comprises a flux. During melting of the solder paste, the copper(I) nitride is reduced. In particular, elemental copper is formed in the process. Advantageously, it is thus possible to apply the solder resist layer over the entire area of ​​the metallization. Structuring of the solder resist layer is therefore not necessary. The reduction of the copper(I) nitride is made possible, for example, by the presence of the flux in the solder paste. In particular, succinic acid enables the reduction of copper(I) nitride to elemental copper.

[0039] According to at least one embodiment of the method, the metallization has at least two regions separated from one another by a recess. In particular, the solder paste is applied in the region of the recess. The solder paste can at least partially fill the recess. Alternatively, the solder paste can be applied such that the recess remains at least partially free of the solder paste, and the solder paste is applied only to the regions of the two metallization regions that border the recess.

[0040] According to at least one embodiment of the method, the solder paste comprises an epoxy resin and / or a silicone resin. The epoxy resin and / or the silicone resin remain in particular in the solder connection. This advantageously makes it possible to achieve a better mechanical connection of the electronic component, which is to be coupled to the connection carrier with the aid of the solder connection, to the connection carrier. In other words, the epoxy resin and / or the silicone resin serve as an additional adhesive in the solder connection. For example, the epoxy resin and / or the silicone resin are cured in a separate step after the solder connection has been created. Alternatively, it is possible for the epoxy resin and / or the silicone resin to cure during the creation of the solder connection, for example when the molten solder material cools down.

[0041] A component is also described. In particular, the component has the connection carrier described here. Furthermore, a solder connection can be created in the component by the method described here. Embodiments, features, and advantages described in connection with the method and the connection carrier therefore also apply to the component, and vice versa.

[0042] According to at least one embodiment, the component comprises a connection carrier described here, an electronic component, and a solder connection between the connection carrier and the electronic component. In particular, the solder connection is arranged between the metallization of the connection carrier and the electronic component.

[0043] In particular, the electronic component is an optoelectronic semiconductor chip configured to generate or detect electromagnetic radiation. The optoelectronic semiconductor chip is, for example, a sapphire flip chip. Advantageously, the component can be used in backlights, backlights for displays, or in a video wall, particularly due to the transparent base body of the connection carrier.

[0044] According to at least one embodiment of the component, the electronic component comprises or is a micro-LED. LED is the abbreviation for light-emitting diode here and below. In particular, the micro-LED is configured to emit electromagnetic radiation.

[0045] Micro-LEDs can have a width, a length, a thickness and / or a diameter of less than or equal to 100 micrometers, in particular less than or equal to 70 micrometers, for example less than or equal to 50 micrometers. In particular, micro-LEDs, for example rectangular micro-LEDs, have an edge length, in particular in plan view of the layers of the layer stack, of a luminous area of ​​less than or equal to 70 micrometers, for example less than or equal to 50 micrometers. A micro-LED is, for example, a light-emitting diode in which a growth substrate has been removed, so that a thickness of the micro-LED is, for example, in the range from 1.5 micrometers inclusive to 10 micrometers inclusive.

[0046] For example, the micro-LED is provided on a wafer with detachable support structures. The micro-LED can be removed from the wafer without causing any damage.

[0047] In particular, micro-LEDs are primarily used in displays. The micro-LEDs form pixels or subpixels and emit light in a defined color. Due to their small pixel size and high density at close spacing, micro-LEDs are suitable for small monolithic displays for augmented reality applications, especially data glasses. In addition, other applications are being developed, particularly for use in data communications or pixelated lighting applications.

[0048] According to at least one embodiment of the component, a conversion region forms a boundary region between the solder connection and the solder resist layer. In other words, the conversion region is arranged between the solder connection and the solder resist layer. In particular, the conversion region at least partially, for example completely, encloses the solder connection when viewed from above.

[0049] For example, the conversion region forms during the melting of the solder paste.

[0050] According to at least one embodiment of the component, the conversion region comprises a reduction product of a material of the solder resist layer. In particular, the reduction product is formed during the melting of the solder paste. If the solder resist layer comprises copper(I) nitride or is formed therefrom, the reduction product is, for example, elemental copper.

[0051] Further advantageous embodiments, refinements and developments of the connection carrier, the method for producing a solder connection and the component result from the following exemplary embodiments shown in conjunction with the figures. Figures 1 to 3 each show schematic

[0052] Sectional views of a connection support according to an embodiment.

[0053] Figures 4 to 8 show schematic sectional views of steps of a method for producing a solder connection according to an embodiment.

[0054] Figures 9 to 13 show schematic sectional views of steps of a method for producing a solder connection according to a further embodiment.

[0055] Figures 14 and 15 show schematic plan views of steps of a method for producing a solder connection according to an embodiment.

[0056] Identical, similar, or functionally identical elements are provided with the same reference symbols in the figures. The figures and the relative sizes of the elements shown in the figures are not to scale. Rather, individual elements, particularly layer thicknesses, may be exaggerated for clarity and / or clarity.

[0057] The exemplary embodiment of a connection carrier 1 according to FIG. 1 has a base body 2. In the present case, the base body 2 is transparent to visible light, IR radiation and / or UV radiation and comprises a plastic. A metallization 3 is applied to the base body 2. The metallization comprises a copper layer 31. In the present case, the metallization 3 is in direct contact with the base body 2. The metallization 3 has a first region 301 and a second region 302. The first region 301 and the second region 302 are electrically insulated from one another by a recess 5. In other words, in the region of the recess 5, the base body 2 is free of the metallization 3.

[0058] In the present exemplary embodiment, a solder resist layer 4 is arranged on the metallization 3. The solder resist layer 4 completely covers the metallization 3. In the present case, the solder resist layer 4 has a thickness of approximately 30 nanometers and is in direct contact with the metallization 3. The solder resist layer 4 comprises copper (I) nitride or consists thereof. In the recess 5, the base body 2 is free of the solder resist layer 4.

[0059] Compared to the exemplary embodiment of the connection carrier 1 in Figure 1, the connection carrier 1 in Figure 2 has a solder resist layer 4 that does not completely cover the metallization 3. Otherwise, the connection carrier 1 in Figure 2 is constructed analogously to that in Figure 1.

[0060] The solder resist layer 4 of the connection carrier 2, which is shown in Figure 2, does not completely cover the metallization 3. In the present case, the metallization 3 is free of the solder resist layer 4 in the region of the recess 5. The solder resist layer 4 is therefore structured.

[0061] The structured solder resist layer 4 of Figure 2 is produced, for example, by covering the areas of the metallization 3 that are to be free of the solder resist layer 4 with a photoresist. The solder resist layer 4 is then applied. After removing the photoresist, the areas that were covered with the photoresist are then free of the solder resist layer 4.

[0062] Figure 3 shows a further exemplary embodiment of a connection carrier 1. In this case, the connection carrier 1 has a base body 2 on which a metallization 3 is arranged. In this case, the metallization comprises a copper layer 31, a nickel layer 32 and a gold layer 33, which are arranged one above the other in this order. The copper layer 31 is in direct contact with the base body 2. The metallization 3 has a first region 301 and a second region 302, which are separated from one another by a recess 5.

[0063] On a side of the metallization 3 facing away from the base body 2, a solder resist layer 4 is arranged, which in this case is in direct contact with the gold layer 33 of the metallization 3. The solder resist layer 4 has a thickness of at most 5 micrometers and is formed from a non-conductive material. The solder resist layer 4 is also arranged in the recess 5. The solder resist layer 4 covers the base body 2 and is in direct contact with the base body 2.

[0064] Figures 4 to 8 show a method for producing a solder connection 12. First, a connection carrier 1 is provided, as shown in Figure 4. The connection carrier 1 shown in Figure 4 has the same structure as already described in connection with Figure 1.

[0065] Figure 5 shows how a template 6 is positioned such that an opening 61 of the template 6 is arranged in the region of the recess 5. In this case, the template 6 is made of a metal.

[0066] With the aid of the stencil 6, a solder paste 7 is applied in the area of ​​the recess 5. Because the solder resist layer 4 on the metallization 3 has a maximum thickness of 5 micrometers, the distance between the stencil 6 and the connection carrier can be kept as small as possible. Therefore, the solder paste 7 can be applied effectively even to small areas.

[0067] As shown in Figure 6, the solder paste 7 is applied such that the first region 301 and the second region 302 of the metallization 3 are covered by the solder paste 7. The recess 5 between the first region 301 and the second region 302 is also filled with the solder paste. In the present case, the solder paste 7 comprises a solder material 71 and a flux 8. The solder material comprises, for example, SnBi, which is characterized by a low melting point. Therefore, SnBi can be used to connect temperature-sensitive electronic components 11 to the connection carrier 1.

[0068] The solder paste 7 is at least partially melted. In the process, the solder material 71 liquefies. As shown in Figure 7, the applied solder paste 7 then separates such that two separate regions with the solder material 71 are formed on the first region 301 and on the second region 302. In other words, the solder material 71 withdraws from the recess 5. A short circuit between the first region 301 of the metallization 3 and the second region 302 is prevented. The presence of the flux 8 in the solder paste 7 leads to a reduction of the solder resist layer 4, so that a conversion region 9 is formed. The conversion region 9 comprises the reduction product of the solder resist layer 4. Since the solder resist layer 4 is formed with copper(I) nitride, the conversion region 9 comprises elemental copper as a reduction product.The conversion region 9 is arranged here between the solder material 71 and the metallization 3. Due to the different properties of the solder resist layer 4 and the conversion region 9, the solder material 71 can only flow on the conversion region 9, but not on the solder resist layer 4. This limits the expansion of the molten solder material 71.

[0069] The size of the conversion region 9 is determined by the content of the flux 8 in the solder paste 7. Thus, the composition of the solder paste 7 can advantageously be used to precisely define the extent of the molten solder material 71 on the metallization 3. In the present case, viewed from above, an edge is formed by the conversion region 9, at least partially around the solder material 71.

[0070] After the solder paste 7 has melted, an electronic component 11 is applied. The solder material 71 from the solder paste 7 solidifies and forms a solder connection 12 between the electronic component 11 and the connection carrier 1. The solder connection 12 is formed with the solder material 71.

[0071] Alternatively, it is possible that the electronic component

[0072] 11 is first applied to the solder paste 7 and then the solder connection 12 is formed by melting and solidifying the solder material 71.

[0073] The component 10 produced in this way is shown in Figure 8. The component 8 has a connection carrier 1 and an electronic component 11. The connection carrier 1 and the electronic component 11 are connected to one another via a solder connection 12. The solder connection 12 has a solder material 71. In the present case, the solder material 71 comprises SnBi. The electronic component 11 is a micro-LED that emits visible light.

[0074] The connection carrier 1 has a base body 2 which is formed from a transparent plastic. A metallization 3 is arranged on the connection carrier 1. The metallization 3 in this case has a copper layer 31 which is in direct contact with the base body 2. A solder stop layer 4 is arranged in places on the metallization 3. The solder stop layer 4 covers the metallization 3 on the side which is facing away from the base body 2. The solder stop layer 4 is formed from copper (I) nitride and also serves as corrosion protection for the metallization 3.

[0075] The metallization 3 in the present case has a first region 301 and a second region 302. The first region 301 and the second region 302 are electrically insulated from one another by a recess 5. The electronic component 11 is in electrical contact with the first region 301 and the second region 302 via the solder connection 12. A solder connection 12 is arranged on both the first region 301 and the second region 302. A conversion region 9 is arranged between the solder connection 12 and the metallization 3. The conversion region 9 comprises copper. The conversion region 9 is in direct contact with the metallization 3, the solder connection 12 and the solder resist layer 4. In the present case, the conversion region 9 borders on the recess 5. Seen in plan view, the conversion region 9 forms an edge around the solder connection 12 at least in places.The conversion region 9 thus forms a boundary region between the solder connection 12 and the solder resist layer 4 .

[0076] A further exemplary embodiment of the method for producing a solder connection 12 is described in connection with Figures 9 to 13. First, as shown in Figure 9, a connection carrier 1 is provided.

[0077] The connection carrier 1 in this case has a base body 2 on which a metallization 3 is arranged. The metallization comprises a copper layer 31, a nickel layer 32 and a gold layer 33, which are arranged one above the other in this order. The copper layer 31 is in direct contact with the base body 2. The metallization 3 has a first region 301 and a second region 302, which are separated from one another by a recess 5.

[0078] On a side of the metallization 3 facing away from the base body 2, a solder resist layer 4 is arranged, which in this case is in direct contact with the gold layer 33 of the metallization 3. The solder resist layer 4 has a thickness of approximately 30 nanometers and is formed with copper(I) nitride. The solder resist layer 4 is not arranged in the recess 5. With the aid of a stencil 6, which in this case has two openings 61, a solder paste 7 is applied to the connection carrier 1. The arrangement of the stencil is shown in Figure 10. The stencil 6 covers the recess 5 in the metallization 3 of the connection carrier 1. The openings 61 are arranged such that the regions of the metallization 3 that border the recess 5 can be provided with the solder paste 7.

[0079] The arrangement of the solder paste 7 on the connection carrier 1 is shown in Figure 11. The solder paste 7 does not fill the recess 5, but the solder paste 7 borders the recess 5. In this case, the solder paste 7 comprises a solder material 71 and a flux 8. The solder paste 7 is in direct contact with the solder resist layer 4 of the connection carrier 1.

[0080] An electronic component 11, in this case a micro-LED, is applied to the solder paste 7, as shown in Figure 12.

[0081] The solder paste 7 is then melted such that the solder material 71 is at least partially liquefied. In the process, a conversion region 9 is formed, as shown in Figure 13. The conversion region 9 is arranged in the present case between the solder material 71 and the gold layer 33. The conversion region 9 is in direct contact with the solder material 71 and the gold layer 33. In the present case, the conversion region 9 comprises a reduction product of the solder resist layer 4, namely elemental copper. The conversion region 9 is formed during the melting of the solder paste 7 by the presence of the flux 8. The flux 8 comprises, for example, succinic acid or is succinic acid.

[0082] The solder material 71 is solidified again and a solder connection 12 is formed between the electronic component 11 and the connection carrier 1.

[0083] It is also possible for the solder paste 7 to additionally comprise an epoxy resin and / or a silicone resin. The epoxy resin and / or the silicone resin serve to further adhere the electronic component 11 to the connection carrier 1. The epoxy resin and / or the silicone resin are cured together with the solder material 71 or in a separate step. The epoxy resin and / or the silicone resin is part of the solder connection 12.

[0084] The component 10 produced in this way is shown in Figure 13. The component 10 of the embodiment in Figure 13 is constructed analogously to the component 10 shown in Figure 8. However, the metallization 3 in the present case has a metallization 3 which comprises a layer stack of a copper layer 31, a nickel layer 32 and a gold layer 33. Furthermore, the base body 2 of the connection carrier 1 is covered with the solder stop layer 4 in the region of the recess 5. In comparison, the recess 5 of the component 10 in Figure 8 is free of the solder stop layer 4.

[0085] Figure 14 shows a schematic plan view of a step of the method for producing the solder connection 12. Figure 14 shows the process stage after the solder paste 7 has been applied to the connection carrier 1. In the present case, the solder paste 7 has been applied to the connection carrier 1 in an approximately circular shape as seen in plan view. The solder paste 7 comprises a solder material 71, for example AuSn, and a flux 8 such as succinic acid. A solder resist layer 4 is arranged on the connection carrier 1 around the solder paste 7. The solder resist layer 4 in the present case comprises copper(I) nitride. The solder paste 7 was applied in the present case by means of stencil printing.

[0086] Figure 15 shows the process stage after the solder paste 7 has been at least partially melted. The structure shown in Figure 15 results in particular from the arrangement shown in Figure 14. The flux 8 present in the solder paste 7 at least partially reduces the copper(I) nitride in the solder resist layer 4 to elemental copper. In this way, a conversion region 9 with the elemental copper is formed between the liquid solder material 71, later the solder connection 12, and the connection carrier 1.

[0087] Due to the solder resist layer 4, the liquid solder material 71 does not completely flow onto a surface of the connection carrier 1. This is evident, for example, in the expansion of the solder material 71. The expansion of the solder material 71, viewed from above, is comparable to the expansion of the solder paste 7 shown in Figure 14.

[0088] The melting of the solder material 71 is additionally prevented by the formation of the conversion region 9. In this case, the conversion region 9 forms a boundary region between the solder material 71 and the solder resist layer 4. The solder material 71 is completely enclosed by the conversion region 9 when viewed from above. In other words, the conversion region 9 forms an edge around the solder material 71.

[0089] The features and exemplary embodiments described in conjunction with the figures can be combined with one another according to further exemplary embodiments, even if not all combinations are explicitly described. Furthermore, the exemplary embodiments described in conjunction with the figures can alternatively or additionally comprise further features according to the description in the general part.

[0090] This patent application claims priority from German patent application 10 2023 116 055 . 9 , the disclosure of which is hereby incorporated by reference .

[0091] The invention is not limited to the embodiments described herein. Rather, the invention encompasses any novel feature and any combination of features, including, in particular, any combination of features in the claims, even if this feature or combination itself is not explicitly stated in the claims or embodiments.

[0092] Reference symbol list

[0093] 1 connection carrier

[0094] 2 basic bodies

[0095] 3 Metallization

[0096] 31 copper layer

[0097] 32 nickel layer

[0098] 33 gold layers

[0099] 301 first area

[0100] 302 second area

[0101] 4 Solder mask layer

[0102] 5 Recess

[0103] 6 template

[0104] 61 Opening

[0105] 7 Solder paste

[0106] 71 Solder material

[0107] 8 flux

[0108] 9 Conversion range

[0109] 10 Component

[0110] 11 electronic components

[0111] 12 solder connection

Claims

Patent claims 1. Connection carrier (1) comprising - a base body (2) with a metallization (3), wherein - a solder resist layer (4) is applied to the metallization (3) at least in places, - the solder resist layer (4) has a thickness of at most 5 micrometers, and - the base body (2) is transparent to visible light, IR radiation and / or UV radiation.

2. Connection carrier (1) according to the preceding claim, wherein the solder stop layer (4) comprises or consists of copper (I) nitride.

3. Connection carrier (1) according to one of the preceding claims, wherein the solder stop layer (4) has a thickness of at most 100 nanometers.

4. Connection carrier (1) according to the preceding claim, in which the metallization (3) comprises or consists of copper.

5. Connection carrier (1) according to one of the preceding claims, in which the metallization (3) has a layer with nickel and / or a layer with gold.

6. Connection carrier (1) according to one of the preceding claims, in which the metallization (3) has at least two regions (301, 302) which are electrically insulated from one another by a recess (5).

7. Connection carrier (1) according to claim 6, in which the solder resist layer (4) in the recess (5) is in direct contact with the base body (2).

8. Connection carrier (1) according to one of claims 6 or 7, in which the metallization (3) on a side facing away from the base body (2) in the region of the recess (5) is free of the solder stop layer (4).

9. Connection carrier (1) according to one of the preceding claims, in which the metallization (3) is completely covered by the solder stop layer on a side facing away from the base body (2).

10. Method for producing a solder connection (12) comprising the steps - Providing a connection carrier (1) comprising a base body (2) with a metallization (3), wherein a solder stop layer (4) is applied at least in places to the metallization (3), the solder stop layer (4) has a thickness of at most 5 micrometers, and the base body (2) is transparent to visible light, IR radiation and / or UV radiation, - applying a solder paste (7) next to or on the solder resist layer (4), - applying an electronic component (11), - at least partial melting of the solder paste (7), and - Forming the solder connection (12) .

11. Method according to the preceding claim, wherein a stencil (6) is used in the application of the solder paste (7).

12. Method according to one of the preceding claims, wherein - the solder resist layer (4) comprises or consists of copper (I) nitride, - the solder paste (7) contains a flux (8), and - during melting of the solder paste (7) the copper (I) nitride is reduced.

13. Method according to one of the preceding claims, wherein - the metallization (3) has at least two regions (301, 302) which are separated from one another by a recess (5), and - the solder paste (7) is applied in the area of ​​the recess (5).

14. Method according to one of the preceding claims, wherein the solder paste (7) comprises an epoxy resin and / or a silicone resin.

15. Component (10) comprising - a connection carrier (1) according to one of claims 1 to 9, - an electronic component (11), and - a solder connection (12) between the connection carrier (1) and the electronic component (11).

16. Component (10) according to the preceding claim, wherein the electronic component (11) comprises or is a micro-LED.

17. Component (10) according to one of the preceding claims, in which - a conversion region (9) forms a boundary region between the solder connection (12) and the solder resist layer (4), and - the conversion region (9) comprises a reduction product of a material of the solder resist layer (4).

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