A measuring sensor of a measuring device for detecting a mass flow or a density of a medium flowing through at least one measuring tube of the measuring sensor, comprising: The at least one measuring tube with an inlet and an outlet, said tube being configured to conduct the medium between the inlet and outlet; at least one exciter, which is configured to cause the at least one measuring tube to oscillate; at least two sensors, which are adapted to detect the deflection of the oscillations of at least one measuring tube; wherein at least one exciter and the sensors each have a coil device with at least one coil and a magnetic device, wherein the magnetic devices can be moved relative to the respective coil device, and wherein the magnetic device and the coil device of an exciter or sensor interact with one another by means of magnetic fields, wherein the coil device has a PCB with at least one PCB layer, wherein the coil is arranged on and/or in at least one PCB layer, wherein the PCB has a first coefficient of thermal expansion, wherein the measuring sensor has a support body which is adapted to hold the measuring tube in place, wherein at least one coil device of the sensors and/or the coil device of the exciter is/are in each case attached to the support body or to a measuring tube by means of a fixture, characterized in that the fixture is adapted to clamp the PCB in order to hold the PCB in place by means of a lateral frictional connection, wherein the PCB is mechanically connected to the fixture by means of at least one retaining element of the fixture, wherein the retaining element has a second coefficient of thermal expansion, wherein the first coefficient of thermal expansion and the second coefficient of thermal expansion have less than 3*10 -6 /Kelvin, and in particular less than 2*10 -6 /Kelvin, and preferably less than 1.5*10 -6 /Kelvin difference between them, wherein the PCB is produced by a sintering process, wherein the PCB has, for example, a ceramic material, wherein the ceramic material is in particular a low-temperature co-fired ceramic. The at least one measuring tube with an inlet and an outlet, said tube being configured to conduct the medium between the inlet and outlet; at least one exciter, which is configured to cause the at least one measuring tube to oscillate; at least two sensors, which are adapted to detect the deflection of the oscillations of at least one measuring tube; wherein at least one exciter and the sensors each have a coil device with at least one coil and a magnetic device, wherein the magnetic devices can be moved relative to the respective coil device, and wherein the magnetic device and the coil device of an exciter or sensor interact with one another by means of magnetic fields, wherein the coil device has a PCB with at least one PCB layer, wherein the coil is arranged on and/or in at least one PCB layer, wherein the PCB has a first coefficient of thermal expansion, wherein the measuring sensor has a support body which is adapted to hold the measuring tube in place, wherein at least one coil device of the sensors and/or the coil device of the exciter is/are in each case attached to the support body or to a measuring tube by means of a fixture, characterized in that the fixture is adapted to clamp the PCB in order to hold the PCB in place by means of a lateral frictional connection, wherein the PCB is mechanically connected to the fixture by means of at least one retaining element of the fixture, wherein the retaining element has a second coefficient of thermal expansion, wherein the first coefficient of thermal expansion and the second coefficient of thermal expansion have less than 3*10 -6 /Kelvin, and in particular less than 2*10 -6 /Kelvin, and preferably less than 1.5*10 -6 /Kelvin difference between them, wherein the PCB is produced by a sintering process, wherein the PCB has, for example, a ceramic material, wherein the ceramic material is in particular a low-temperature co-fired ceramic.