Breakable temperature sensor comprising rohs-compatible fixing drop

Abstract

The present invention relates to glass compositions, in particular fixing drops, a passive component, a method for producing leaded passive components, a passive component obtainable by the method, and the use of such glass compositions for strain relief of lead wires on passive components.

Description

[0001] DESCRIPTION

[0002] Breakable temperature sensor with RoHs compliant fixative drop

[0003] The present invention relates to glass compositions, in particular fixing drops, a passive component, a process for producing a passive component, a passive component obtainable by this process, and the use of such glass compositions for strain relief of connecting wires on passive components.

[0004] Passive components are generally understood to be those components that, unlike active components, do not exhibit an amplifying effect or have a control function. Examples of passive components include resistors, capacitors, sensors, and heaters.

[0005] According to the invention, a passive component preferably comprises a substrate, a multilayer structure located on the substrate, at least one connecting wire, and a glass composition for strain relief of the at least one connecting wire. The multilayer structure, in turn, preferably comprises at least one connecting pad to which the at least one connecting wire is fixed, at least one electrical conductor track, and at least one dielectric layer, for example a screen-printed glass layer, arranged between the glass composition and the substrate and covering the conductor track but leaving the connecting pad substantially exposed.

[0006] The glass composition, in particular the fixing drops, primarily serves to provide strain relief for the at least one connecting wire. This ensures that the at least one connecting wire is securely fixed, while also protecting the areas covered by it from potential external influences such as condensed air humidity. Furthermore, the glass composition also has a protective function; for example, the glass composition can protect the connecting wires from electrical short circuits caused by contact with a conductive housing.

[0007] Custom-made passive components are generally too costly for mass production. Consequently, for mass production of passive components, multiple structures are arranged on a common substrate, with at least one connecting wire mechanically fixed to each structure. By applying a continuous glass composition, which runs as a continuous layer over several structures and at least partially covers them, the connecting wires are relieved of strain. The subsequent separation of the components then involves cutting through the substrate and the glass compositions.

[0008] There are various options for separating passive components, with the passive components typically being separated by sawing. While this approach involves additional effort, particularly when the passive components comprise a hard substrate, e.g., based on Al2O3, it is applicable regardless of the glass composition and is associated with low failure rates. Alternatively, separation by breaking is significantly less labor-intensive and therefore more cost-effective. However, this method faces the challenge that breaking glass is often associated with higher failure rates.

[0009] Since most glass compositions do not fracture in a defined manner, glasses that have not been optimized for this type of separation exhibit oblique fracture surfaces or fracture at the wrong location, i.e., not through the predetermined breaking point in the substrate. A glass composition that can withstand the tensile stresses acting on the fixation during fracture is advantageous for such a long time that the predetermined breaking point in the substrate breaks first, thus determining the fracture position in the glass composition. A glass composition with high elasticity, i.e., a Young's modulus of approximately 45 GPa or less, is particularly advantageous in order to exhibit this fracture toughness.

[0010] Preferably, the glass composition according to the invention has a modulus of elasticity of 45 GPa or less.

[0011] The fracture surface is understood to be the newly created surface of a passive component due to singulation. In this context, microcracks or spalling at the fracture surface are examples. Furthermore, the microcracks can also propagate into the interior of the glass composition, although these are difficult to detect. Passive components with such poorly fractured glass compositions are often not suitable for further use. Even more serious are damages (probable microcracks) within the glass composition, which arise from the mechanical stress during fracture above the wires, where the glass composition is at its thinnest. These are not visually detectable and only propagate through the glass volume when the component is subjected to thermal stress. Fine hairline cracks then appear above the connecting wires.

[0012] Lead-containing glass compositions known from the prior art exhibit advantageous mechanical stability, good electrical properties, and good breaking properties. This results in a particularly advantageous manufacturing process: the glass composition can be applied as a continuous strand over the connecting wires, and the passive components can then be separated without high failure rates due to defective glass or glass broken in the wrong place.

[0013] However, lead-free glass compositions are required to protect the environment. As a result, the EU has restricted the use of certain hazardous substances in electrical and electronic equipment through the RoHS directive. In particular, the specified maximum limit for lead of 1000 ppm requires that existing glass compositions be adapted accordingly for use in the aforementioned technical application.

[0014] A fundamental problem that arises in the provision of lead-free glass compositions is therefore to replace the lead-containing components while maintaining the advantageous properties, in particular the good breaking properties.

[0015] One way to at least circumvent the breakability requirement would be to attach the glass composite to the connecting wires only at specific points, thus eliminating the need to break the glass composite. While this approach would be possible in principle, it would also involve additional effort and would therefore offset the additional effort saved by avoiding sawing through the glass.

[0016] Lead-free glasses that contain alkali display good refractive properties but are not suitable as glass compositions for passive components. A problem that is increasingly evident with such glasses is the occurrence of polarization effects, also known as capacitor effects, which are described, for example, in US 2021 / 0396590 A1, which is hereby fully incorporated. In the context of the application, polarization effects are understood in particular to mean that a charge separation occurs at the connecting wires in the glass composition. When an electric current is applied, the measured electrical voltage consequently deviates from the stationary value. In the following, this voltage difference is referred to as the voltage offset. Since the polarization effect, and thus the voltage offset, does not change linearly as a function of temperature, it is not possible to take this effect into account using a factor.

[0017] The size of the measured polarization effect depends on the exact measurement method or the measurement time used and can be determined according to the following measurement method:

[0018] The resistance of passive components, especially temperature sensors, is measured in two ways. a) Measurement by reversing the voltage polarity.

[0019] A voltage of +250 mV is applied, any capacitor present is charged and the resistance is measured after one minute.

[0020] The voltage was then reversed, and measurements were taken again one minute later. A first average was calculated from both measurements. Any thermoelectric voltage present was then mathematically compensated. Temperature 1 of the sensor was determined from the average of both measurements. b) Fast measurement with voltage source disconnection.

[0021] In this process, the sensor in the measuring device is internally disconnected from the voltage source every 0.2 seconds, the input voltage then present is measured, and mathematically subtracted from the measured voltage. Any thermoelectric voltage present is also compensated for in this way. Here, too, the resistance is measured after approximately one minute, the voltage is reversed, and measured again after another minute, and a second average value is calculated. A temperature of 2 was determined from this second average value.

[0022] Consequently, in the context of the present disclosure, the polarization effect is specified as the difference between temperature 1 and temperature 2.

[0023] If the difference exceeds 0.5°C, the polarization effect is considered strong. The voltage offset can become so large, especially at high temperatures, that the required tolerance classes for passive components cannot be maintained across the entire temperature range. This applies particularly to wired sensor elements with resistances greater than 500 ohms. During the development work for this application, it was surprisingly discovered that the lithium and sodium ion content is primarily responsible for the strength of the voltage offset in lead-free glass compositions.

[0024] For passive components with nominal resistances below 1000 ohms, the polarization effect is more difficult to measure dynamically, but it is less accurate in the measured values ​​determined with the component.

[0025] In this case, the standardized polarization effect is defined as the polarization effect that results from a passive component with the same lead geometry and glass composition, but with a temperature-dependent nominal resistance of 1000 ohms between the lead wires. From now on, the term "capacitor effect" will be used as a synonym for the standardized capacitor effect defined in this way. Thus, the term and measurement specification for the capacitor effect are comprehensibly extended to all passive resistors, and in particular to heaters with resistances below 1000 ohms.

[0026] With this measurement method, as well as with the functionality of the passive component, the substrate quality is also significant, as a short-circuit current can also flow through it. This is especially true for passive components that use substrates with specific resistances above 10 9The insulation resistance of the fixative droplet can influence the measurement error (at 500°C). Therefore, Al2O3 substrates, MgO substrates, many glass substrates, or some doped zirconium oxide substrates, as well as their mixtures or layered structures, are suitable as substrates for the passive components with the glass composition according to the invention.

[0027] This also applies to passive components on more conductive substrates, provided that a sufficiently high insulation effect has been applied between the conductive structure and the substrate by at least one non-conductive layer with sufficiently high dielectric strength. To minimize the component's measurement error, a combination of substrate, any necessary electrical insulation layer, and the glass composition according to the invention is advantageous in such a way that a limit of 17 MΩ at 500°C as the total insulation resistance between the resistance sections is exceeded. A passive component with fixation drops is particularly advantageous for precise measurement if the insulation resistance between the resistance sections exceeds 17 MΩ at 550°C.

[0028] Since the polarization effect leads to a decrease in insulation resistance at high temperatures and, at the same time, the resistance increases in components with electrically conductive structures with a positive temperature coefficient (PTC), the combination of such structures with the glass composition according to the invention is advantageous.

[0029] The object of the present invention is to provide a glass composition that can be broken after application to a substrate, minimizing the aforementioned disadvantages of this type of separation, while simultaneously avoiding environmentally harmful components that impair electrical properties. In particular, the object of the present invention is to provide a glass composition, in particular fixation drops, for strain relief of connecting wires on passive components on an inorganic substrate, wherein the glass composition contains small amounts of Na and Li and comprises less than 1000 ppm of lead.

[0030] This object was surprisingly achieved by a glass composition according to claim 1, in particular by a glass composition, in particular fixing drops, for strain relief of connecting wires on passive components, in particular sensors, preferably temperature sensors, or heaters on an inorganic substrate, in particular metal oxide, semiconductor and / or glass substrate, wherein the glass composition comprises SiO2, Al2O3, B2O3 and ZnO, characterized in that the glass composition comprises less than 1000 ppm of lead, and in that the glass composition comprises less than 2 wt.% Na, less than 0.2 wt.% Li, and / or less than 2 wt.% as the sum of Na and Li, in each case measured by ICP, and based on the total weight of the glass composition. The amounts of Na and Li preferably relate to the amount of the Na ions. + and Li + , so that in the context of this disclosure Na and Na + , or Li or Li +can be used equivalently. This applies analogously to lead, which can also be understood as the corresponding lead ion.

[0031] Numerous specific details are discussed below to provide a thorough understanding of the subject matter. However, it will be apparent to one skilled in the art that the subject matter can be practiced and recreated without these specific details.

[0032] All features of one embodiment may be combined with features of another embodiment if the features of the different embodiments are compatible.

[0033] The terminology used in the description of the present disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the subject matter. As used in this description and the claims, the singular forms "a," "an," and "the" are intended to include the plural forms, unless the context clearly dictates otherwise. The reverse is also true, meaning that the plural forms are intended to include the singular forms. It is also understood that the term "and / or," as used herein, refers to and includes all possible combinations of one or more of the related listed elements.It is further understood that the terms "includes," "including," "comprises," and / or "comprising," when used in the present description and claims, specify the presence of the stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0034] In the present description and claims, the terms "includes", "comprises" and / or "comprising" may also mean "consisting of", that is, the presence or addition of one or more other features, steps, operations, elements, components and / or groups is excluded.

[0035] The concentration of lithium, sodium and lead in the inventive

[0036] Glass composition was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The inductively coupled plasma method relies on the use of a very hot (approx. 10,000 K) argon plasma to excite the optical emission of the elements under analysis. Lead concentrations are preferably measured according to IEC 62321-5: 2013, and lithium and sodium concentrations are measured according to DIN EN ISO 11885.

[0037] The glass composition for strain relief of connecting wires is located on the structure in such a way that the connection pads for the connecting wires are covered.

[0038] Advantageously, the glass composition at least partially covers an underlying screen-printed glass layer. This achieves a particularly high adhesive force between the glass composition and a screen-printed glass layer. This is particularly advantageous because it largely ensures that the glass composition does not detach from the passive component under increased mechanical stress.

[0039] Since passive components are exposed to elevated temperatures during operation or due to their surroundings, water hammer can occur on the hot passive component, for example, in humid atmospheres. Special protective measures are usually necessary to prevent thermal shock on the surface of the passive component.

[0040] Advantageously, these additional protective measures can be dispensed with in the glass composition according to the invention because it has low thermal conductivity. This property is particularly advantageous for its preferred use as a fixative drop on a passive component. It is also advantageous that the glass composition according to the invention has a low coefficient of expansion in the direction transverse to an underlying screen-printed glass layer.

[0041] The glass composition according to the invention is preferably characterized in that the glass composition can be melted or sintered with the at least one screen-printed glass layer for strain relief of the at least one connecting wire.

[0042] The glasses can be similar or identical, at least in terms of their constituents; alternatively, the glasses can be different in their constituents, preferably so that they cannot be fused or sintered together. The glass composition according to the invention is further preferably characterized in that the glass composition comprises from 20 to 55% by weight, preferably from 25 to 50% by weight, of silicon dioxide, from 5 to 15% by weight, preferably from 6 to 14% by weight, of boron oxide, and from 4 to 18% by weight, preferably from 5 to 17% by weight, of aluminum oxide, based on the total weight of the glass composition.

[0043] More preferably, the glass composition according to the invention additionally comprises from 5 to 14 wt.%, preferably from 6 to 13 wt.%, of zinc oxide, based on the total weight of the glass composition.

[0044] Since the glass composition according to the invention may be an inhomogeneous mixture, the stated wt. % refers to the average content in the glass composition or the fixing drop. Local deviations in the wt. % in the glass composition or in the fixing drop are possible, but they balance out to the stated wt. %.

[0045] The glass composition according to the invention is further preferably characterized in that the glass composition comprises from 35 to 55 wt.% silicon dioxide, from 9 to 14 wt.% boron oxide, from 6 to 9 wt.% zinc oxide, from 4 to 7 wt.% strontium oxide, from 2 to 5 wt.% potassium oxide, or from 35 to 55 wt.% silicon dioxide, from 8 to 15 wt.% bismuth oxide, from 6 to 11 wt.% boron oxide, from 6 to 10 wt.% zinc oxide, from 4 to 8 wt.% strontium oxide, from 2 to 6 wt.% potassium oxide, or from 20 to 55 wt.% silicon oxide and lanthanum oxide, from 11 to 14 wt.% boron oxide, from 9 to 13 wt.% zinc oxide, from 3 to 6 wt.% calcium oxide, in each case based on the total weight of the glass composition.

[0046] The glass composition according to the invention is further more preferably characterized in that the glass composition comprises from 35 to 55 wt.% silicon dioxide, from 9 to 14 wt.% boron oxide, from 6 to 9 wt.% zinc oxide, from 4 to 7 wt.% strontium oxide, from 2 to 5 wt.% potassium oxide, or from 35 to 55 wt.% silicon dioxide, from 8 to 15 wt.% bismuth oxide, from 6 to 11 wt.% boron oxide, from 6 to 10 wt.% zinc oxide, from 4 to 8 wt.% strontium oxide, from 2 to 6 wt.% potassium oxide, or from 20 to 55 wt.% silicon oxide and lanthanum oxide, from 11 to 14 wt.% boron oxide, from 9 to 13 wt.% zinc oxide, from 3 to 6 wt.% calcium oxide, in each case based on the total weight of the glass composition.

[0047] Since it is not possible to account for the polarization effect in most cases and measurement environments, it is desirable to use glass compositions that exhibit only a low polarization effect. As explained above, low concentrations of sodium and lithium in the glass composition lead to a low polarization effect, so it is particularly advantageous if the glass compositions contain only small amounts of these elements. Furthermore, lithium acts as a platinum poison and is therefore preferably contained in particularly small amounts in the glass composition according to the invention.

[0048] The glass composition according to the invention is further preferably characterized in that the glass composition contains less than 2.0 wt.% Na or less than 1.9 wt.% Na or less than 1.8 wt.% Na or less than 1.7 wt.% Na or less than 1.6 wt.% Na or less than 1.5 wt.% Na or less than 1.4 wt.% Na or less than 1.3 wt.% Na or less than 1.2 wt.% Na or less than 1.1 wt.% Na or less than 1.0 wt.% Na or less than 0.9 wt.% Na or less than 0.8 wt.% Na or less than 0.7 wt.% Na or less than 0.6 wt.% Na or less than

[0049] 0.5 wt% Na or less than 0.4 wt% Na or less than 0.3 wt% Na or less than 0.2 wt% Na or less than 0.1 wt% Na

[0050] It is particularly preferred that the glass composition according to the invention comprises less than 2.0 wt.% Na or less than 1.5 wt.% Na or less than 1.0 wt.% Na (each determined by ICP-OES, based on the total weight of the glass composition)

[0051] In particular, the glass composition according to the invention is characterized in that the glass composition comprises less than 1.5 wt.% Na (determined by ICP-OES, based on the total weight of the glass composition).

[0052] The glass composition according to the invention is further preferably characterized in that the glass composition comprises less than 0.2 wt% Li or less than 0.15 wt% Li or less than 0.1 wt% Li or less than 0.05 wt% Li (each determined by ICP-OES, based on the total weight of the glass composition).

[0053] Consequently, the glass composition according to the invention is further preferably characterized in that the glass composition comprises less than 1.5 wt% as the sum of Na and Li, preferably less than 1.0 wt% as the sum of Na and Li, in each case determined by means of ICP-OES, based on the total weight of the glass composition.

[0054] Although avoiding lithium and sodium in the glass composition has proven successful in minimizing the polarization effect, the occurrence of the polarization effect can alternatively be determined experimentally. To do this, a current-voltage curve of a passive component containing the glass composition under investigation can be recorded. An initial voltage is applied and gradually increased to a final voltage. The voltage is then reduced to the initial value, starting from the final voltage. If the measured current assumes different values ​​when the voltage is reduced than when the voltage is increased, this becomes visible in the current-voltage curve in the form of hysteresis. Hysteresis in the current-voltage curve therefore indicates a polarization effect in the glass composition.Even if no hysteresis can be detected in the ideal case, certain deviations from the ideal behavior may be tolerable under certain circumstances.

[0055] As a further indication of whether a glass composition favors the polarization effect in a specific temperature range, the insulation resistances between two connecting wires on a passive component without conductive tracks can be measured. For passive components with low resistances, especially those below 500 ohms, and especially for heaters, this is a more useful way to assess the polarization effect.

[0056] The glass composition according to the invention is further preferably characterized in that the glass composition has a polarization effect of absolutely less than 0.5 K at temperatures of 500°C to 550°C, in particular less than 0.1 K at temperatures of 500°C and / or less than 0.3 K at temperatures of 550°C.

[0057] The glass composition is preferably electrically insulating and suitable for insulation at an applied electric field strength of at least 3 V / cm, preferably at least 4 V / cm, in particular at least 5 V / cm, at room temperature.

[0058] The glass composition is preferably electrically insulating at an applied electric field strength of at least 3 V / cm, preferably at least 4 V / cm, in particular at least 5 V / cm, at 550 °C.

[0059] The electrical insulation is also designed in particular for the application of alternating voltage and / or pulsed direct voltage.

[0060] In the preferred embodiment, the glass composition is very fine-pored and homogeneous on small scales of 0.1 mm, so that an insulation value of 17 MQ between two wires with a wire cross-section of less than 0.0625 mm 2The spacing of the wires from one another is maintained at a maximum of 0.4 mm, preferably at most 0.3 mm, particularly preferably at most 0.2 mm, over a length of at least 0.5 mm. In a preferred embodiment of the invention, the wires are round wires.

[0061] In another embodiment of the invention, the wires are flattened at the tips or the wires taper in at least one dimension of the cross-section.

[0062] In a further embodiment of the invention, the wires are flat wires.

[0063] The present invention further relates to a passive component, in particular a sensor, preferably a temperature sensor, or heater.

[0064] The present invention further relates to a passive component, in particular a sensor, preferably a temperature sensor, or heater, comprising connecting wires and an inorganic substrate, in particular a metal oxide, semiconductor and / or glass substrate.

[0065] The present invention further relates to a passive component, in particular a sensor, preferably a temperature sensor, or heater, comprising connecting wires and an inorganic substrate, in particular a metal oxide, semiconductor and / or glass substrate, characterized in that the connecting wires are strain-relieved by the applied glass composition according to the invention.

[0066] Breaking separation has established itself as a particularly cost-effective process for passive components. This separation method has proven advantageous when predetermined breaking points are present in the substrate, thus allowing for easy breaking, especially with hard substrates.

[0067] The passive component according to the invention is further preferably characterized in that the passive component was obtained by singulation, wherein the singulation comprises breaking, in particular at at least one predetermined breaking point.

[0068] Even though, from a process-economic perspective, dicing by breaking is preferable to sawing, providing suitable glass compositions suitable for this method presents several challenges. In particular, the occurrence of critical cracking should preferably be minimized in order to reduce the failure rate during production. The passive component according to the invention is further preferably characterized in that the glass composition exhibits minimal critical cracking during the dicing of the passive components.

[0069] For the purposes of the present invention, crack formation is characterized based on the cutting angles. During the separation of the passive components, at least two passive components are separated from each other by breaking. The resulting fracture surface on one of the passive components is ideally perpendicular to the substrate plane, so that the four cutting angles between the fracture surface and the substrate plane are all 90°. Since secondary angles add up to 180°, it is not necessary to consider all angles; instead, the crack formation can be qualified by specifying the smallest cutting angle. Under real conditions, however, the passive components do not fracture ideally; considerable deviations can occur.These deviations are tolerable, but it is advantageous to avoid critical cracks and microcracks in the glass composition so that the failure rate in the production of passive components is reduced to a minimum.

[0070] Critical crack formation is therefore understood to mean that the smallest intersection angle between the fracture surface and the substrate plane of the passive component is less than 45°.

[0071] It is therefore preferred that the smallest intersection angle between the fracture surface and the substrate plane of the passive component is more than 45°, more preferably 60°, further preferably more than 70°.

[0072] Microcracks are fine cracks in the glass composition that are difficult to detect. These microcracks can occur when the glass composition breaks and are detected, for example, by optical inspection after the passive components have been manufactured.

[0073] The passive component according to the invention is further preferably characterized in that the passive component is a temperature sensor which complies with the validity of the tolerance class F 0.3 (B) at a temperature of -70 °C to 500 °C.

[0074] Further preferred embodiments of the passive component according to the invention meet tolerance class F0.3 (B) at a temperature of -70 °C to 500 °C. In a further embodiment of the invention, at least one end of at least two connecting wires is at least partially encased by a coherent glass element formed by the applied glass composition.

[0075] A coherent glass element is understood to mean, in particular, a glass element that does not have separate sections. Rather, the glass element is formed during the manufacturing process from a glass material that is / is applied coherently.

[0076] In other words, two connecting wire ends are at least partially encased by a continuous glass element formed by the applied glass composition. The two ends of the connecting wires / the two connecting wire ends are the ends that are arranged in structural proximity to one another, so that a continuous glass element encases these two ends at least partially, in particular completely within the scope of the end lengths specified below.

[0077] Within the scope of the invention, a radial connection of the ends of the connecting wires is also present if the end is in contact with another element, at least in part, in a radial and / or longitudinal extension, in particular if it is connected to another element. At a direct connection point with a contact surface, the end may, for example, not be encased by the glass element at this connection point, so that the glass element encloses the end in other radial sections that do not form a connection point, so that the end as a whole is not exposed in any radial section.

[0078] Preferably, the ends of the at least two connecting wires in the glass element are positioned substantially parallel to each other, in particular parallel to each other. A substantially parallel arrangement allows a deviation in parallelism of ± 3°, in particular ± 2°, in particular ± 1°.

[0079] Preferably, the ends of the at least two connecting wires in the glass element are positioned substantially parallel to each other, in particular parallel to each other, and the ends have the same orientation. The ends of the at least two connecting wires have the same orientation, in particular, when they are aligned in the same direction.

[0080] A particular embodiment of the invention is an axial component. The ends of the at least two connecting wires in the glass element are positioned substantially parallel to each other, in particular parallel to each other, and the ends have opposite orientations.

[0081] In a preferred embodiment of the invention, the ends of the at least two connecting wires each have a length of at least 0.3 mm, in particular of at least 0.5 mm, within a / the glass element.

[0082] In a special design, the total length of the connecting wires is no longer than 12 mm.

[0083] Adhesion of the glass material, in particular the glass element, to the passive component, in particular the sensor, preferably does not occur via anodic bonding at a connection point. Preferably, the adhesion of the glass material, in particular the glass element, to the passive component, in particular the sensor, occurs at least partially through sintering or sintered bonding.

[0084] Particularly preferably, adhesion occurs through the formation of a sintered bond with molten glass components in the volume of the glass element and at the interface to the passive component.

[0085] Particularly preferably, the connecting wires, in particular the ends of the connecting wires, are not covered by individual glass elements.

[0086] The smallest distance between the connecting wires is preferably less than 2 mm, in particular 1.0 mm - 0.3 mm, particularly preferably 0.4 mm. This minimum distance relates in particular to the ends of the wires that are embedded in the glass element. The distance between the connecting wires is defined as the distance between the wire surfaces. In other words, the above-mentioned distance is not the distance between the wire centers of the two connecting wires. In a further embodiment of the invention, at least one connecting pad, preferably at least two connecting pads, is formed below at least one glass element, preferably below the glass element, which pad / pads serve to make contact with the at least two ends of the connecting wires.In this embodiment, the two connection pads are further preferably arranged in close proximity to one another and have a distance of less than 0.3 mm, in particular less than 0.2 mm, most preferably less than 0.15 mm, from one another.

[0087] The present invention further relates to a method for producing passive components, in particular for producing the passive component according to the invention. The method comprises the following steps, whereby the order of the individual steps cited below is not mandatory.

[0088] - Providing an inorganic substrate, in particular a metal oxide or semiconductor substrate or a glass substrate, on which several structures are arranged, in particular in a row,

[0089] - Forming predetermined breaking points in the inorganic substrate between the structures, in particular by means of a laser and / or by means of mechanical ablation,

[0090] - Attaching at least one connecting wire to each of the structures,

[0091] - covering the connecting wires by applying a continuous glass element, in particular by applying the glass composition according to the invention, over the plurality of structures,

[0092] - Separation of the passive components by breaking the inorganic substrate and the continuous glass element at the predetermined breaking points.

[0093] The above sequence of steps is not mandatory, but encompasses all technically feasible sequences. For example, it would be possible to create the predetermined breaking points only after a continuous glass element has been applied.

[0094] In a preferred embodiment of the method according to the invention, the method steps are carried out in the order listed. In another preferred embodiment of the method according to the invention, the structure comprises a screen-printed glass layer. The step of covering the connecting wires by applying a continuous glass element would then be configured as follows.

[0095] - Covering the structure-facing ends of the connecting wires and at least partially covering the screen-printed glass layer by applying a continuous glass element, in particular by applying the glass composition according to the invention, over the plurality of structures, wherein the structures are covered by 60%, preferably by 80%, particularly preferably by 100%. Complete coverage of the region of the connecting wires above the substrate is further preferred.

[0096] With this preferred embodiment of the method according to the invention, the interface between the glass element and the screen-printed glass layer transitions into a mixing zone approximately 5 to 20 μm thick. This achieves a particularly high adhesive force between the glass element and the screen-printed glass layer. This is particularly advantageous in the production of passive components, as it minimizes the risk of the glass element being blown off during separation due to breakage of the passive components. Furthermore, the electrical breakdown strength of the passive component can be increased.

[0097] All preferred embodiments and definitions for the passive components according to the invention apply analogously to the method according to the invention.

[0098] The present invention further relates to a passive component obtainable by the method described above.

[0099] The present invention also relates to the use of a glass composition as described above for strain relief of connecting wires on passive components, in particular as described above or obtainable by the method described above.

[0100] In a preferred embodiment of the use according to the invention, the passive components were obtained by singulation, wherein the singulation comprises breaking, particularly at predetermined breaking points. The preferred embodiments listed above for the glass composition according to the invention and the passive component according to the invention also apply to the method according to the invention, the passive component obtained by this method, and the use of the glass composition.

[0101] Description of the characters

[0102] Figure 1 shows a current-voltage curve for measuring the polarization effect of a passive component comprising a lead-free glass composition with a low lithium and sodium content. The current-voltage curve shows no hysteresis, which indicates the absence of a polarization effect.

[0103] Figure 2 shows a current-voltage curve for measuring the polarization effect of a passive component comprising a lead-free glass composition with an increased content of lithium and sodium ions. The current-voltage curve exhibits hysteresis, which indicates the presence of the polarization effect.

[0104] Figure 3 shows a schematic representation of a passive component without a glass element for strain relief of connecting wires. A connection pad is located on the substrate (5).

[0105] (3) and a screen-printed glass layer (4). A connecting wire (2) is attached to the connection pad (3).

[0106] Figure 4 shows a schematic representation of a passive component according to the invention. A connection pad (3) and a screen-printed glass layer are located on the substrate (5).

[0107] (4). A connecting wire (2) is attached to the connecting pad (3), which is strain-relieved by a glass composition (1).

[0108] The invention is explained in more detail below using non-limiting examples. Examples

[0109] Example 1:

[0110] Example 2:

[0111]

[0112] The inventive glass compositions 1 to 3 according to Example 1 are lead-free and have a low lithium and sodium content. They exhibit no critical cracking upon breaking and exhibit only a slight polarization effect.

[0113] Although glass compositions 4 to 8 according to Example 2 are lead-free and do not exhibit critical cracking upon breaking, they do exhibit an undesirably high polarization effect. The results of the polarization measurements and the cracking upon breaking of the respective glass compositions are summarized in the following tables for clarity: The polarization effect of compositions 1 to 8 was determined according to the described measurement method, with the respective compositions being measured in conjunction with a Pt 1000 sensor. The measured mean values ​​of two temperature sensors with the specified glass composition are given.

[0114] Compositions 1 to 3 according to the invention have a lower content of lithium and sodium and a low polarization effect.

[0115] Compositions 4 and 5, on the other hand, exhibit increased lithium and sodium contents and a significant polarization effect. The lithium-free compositions 6 to 8 also exhibit an increased polarization effect, as these compositions exhibit increased sodium contents.

[0116] Example 3

[0117] In addition, the insulation resistances between two

[0118] The glass composition was measured on strain-relieved conductor wires on a temperature sensor without a continuous conductor path. It was found that the insulation resistances of glass compositions 1, 2, and 3 decrease sharply with a temperature change from 500°C to 550°C.

Claims

CLAIMS 1. Glass composition, in particular fixing drops, for strain relief of connecting wires on passive components, in particular sensors, preferably temperature sensors, or heaters on an inorganic substrate, in particular metal oxide, semiconductor and / or glass substrate, wherein the glass composition comprises SiO2, Al2O3, B2O3 and ZnO, characterized in that the glass composition comprises less than 1000 ppm of lead, and in that the glass composition comprises less than 2 wt% Na, less than 0.2 wt% Li, and / or less than 2 wt% as the sum of Na and Li, in each case measured by means of ICP, and based on the total weight of the glass composition.

2. Glass composition according to claim 1, characterized in that the glass composition comprises from 20 to 55 wt.%, preferably from 25 to 50 wt.%, of silicon dioxide, from 5 to 15 wt.%, preferably from 6 to 14 wt.%, of boron oxide, and from 4 to 18 wt.%, preferably 5 to 17 wt.%, of aluminum oxide, based on the total weight of the glass composition.

3. Glass composition according to claim 1 or 2, characterized in that the glass composition contains from 35 to 55 wt% silicon dioxide, from 9 to 14 wt% boron oxide, from 4 to 7 wt% strontium oxide, from 2 to 5 wt% potassium oxide, or from 35 to 55 wt% silicon dioxide, from 8 to 15 wt% bismuth oxide, from 6 to 11 wt% boron oxide, from 4 to 8 wt% strontium oxide, from 2 to 6 wt% potassium oxide, or from 20 to 55 wt.% silicon oxide and lanthanum oxide, from 11 to 14 wt.% boron oxide, from 3 to 6 wt.% calcium oxide, each based on the total weight of the glass composition.

4. Glass composition according to one of the preceding claims, characterized in that the glass composition comprises less than less than 1.5 wt% as the sum of Na and Li, preferably less than 1.0 wt% as the sum of Na and Li, in each case determined by means of ICP, based on the total weight of the glass composition.

5. Glass composition according to one of the preceding claims, characterized in that the glass composition is electrically insulating at an applied electric field strength of at least 3 V / cm, preferably at least 4 V / cm, in particular at least 5 V / cm, at 550 °C.

6. Passive component, in particular sensor, preferably temperature sensor, or heater, comprising connecting wires and an inorganic substrate, in particular metal oxide, semiconductor and / or glass substrate, characterized in that the connecting wires are strain-relieved by an applied glass composition according to one of claims 1 to 5.

7. Passive component according to claim 6, characterized in that the passive component was obtained by singulation, wherein the singulation comprises breaking, in particular at at least one predetermined breaking point.

8. Passive component according to one of claims 6 to 7, characterized in that the passive component is a temperature sensor which complies with the validity of tolerance class F 0.3 (B) at a temperature of -70 °C to 500 °C.

9. Passive component according to one of claims 6 to 8, characterized in that at least one end of at least two connecting wires is at least partially covered by a coherent glass element formed by the applied glass composition.

10. Passive component according to claim 9, characterized in that the ends of the at least two connecting wires in the glass element are positioned substantially parallel to one another, in particular parallel to one another.

11. Passive component according to claim 9 or 10, characterized in that the ends of the at least two connecting wires each have a length of at least 0.3 mm, in particular of at least 0.5 mm.

12. A method for producing passive components, in particular according to one of claims 6 to 11, comprising the steps: - Providing an inorganic substrate, in particular a metal oxide or semiconductor substrate or a glass substrate, on which several structures are arranged, in particular in series, - Forming predetermined breaking points in the inorganic substrate between the structures, in particular by means of a laser and / or by means of mechanical ablation, - Attaching at least one connecting wire to each of the structures, - Covering the connecting wires by applying a continuous glass element, in particular comprising a glass composition according to one of claims 1 to 5, about the multiple structures, - Separation of the passive components by breaking the inorganic substrate and the continuous glass element at the predetermined breaking points.

13. Passive component obtainable by the method according to claim 12.

14. Use of a glass composition according to one of claims 1 to 5 for strain relief of connecting wires on passive components, in particular according to one of claims 6 to 11 or claim 13.

15. Use according to claim 14, characterized in that the passive components were obtained by singulation, wherein the singulation comprises breaking, in particular at predetermined breaking points.

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