Electric device, in particular a microphone having re-adjustable sensitivity, and adjustment method

Abstract

In order to adjust an electric device, it is proposed to integrate a programmable memory unit into the device and to address said programmable memory unit without enlarging the footprint, via contact areas that are obtained by dividing previous contact areas. In this case, an adjustment value in particular for compensating for a fault tolerance is fed into the memory unit, an operating parameter being readjusted with the aid of said adjustment value. In each case two divided contact areas are short-circuited via a common soldering location during the mounting of the device.

Claims

1. An electric device, comprising a carrier comprising a first surface having grid areas arranged in a grid, contact areas arranged in the grid areas, an electromechanical component, arranged in or on a second surface of the carrier, an integrated circuit, a programmable memory unit, wherein the electromechanical component and the integrated circuit are electrically connected to one another and to the contact areas, the number of grid areas corresponds exactly to the number of those contact areas which are required for the proper function of the device, each of the grid areas corresponds to a soldering location that completely fills the grid area, at least one of the grid areas comprises two smaller contact areas that share a grid area, the smaller contact areas are arranged relative to one another in the shared grid area such that they are automatically short-circuited after the soldering of the device via the soldering location thereby rendering further influencing or programming of the programmable memory unit impossible after the smaller contact areas have been short-circuited without disturbing the proper function of the device, one of the smaller contact areas is configured to be used to carry out one-time programming (OTP) of the programmable memory unit, an other of the smaller contact areas is configured to be used to carry out the proper function of the device.

2. The device according to claim 1, wherein the one of the smaller contact areas is connected to the programmable memory unit.

3. The device according to claim 2, embodied as a microphone that supplies an analog output signal, wherein the integrated circuit regulates the operation and the sensitivity of the microphone and also the strength of the output signal, wherein the programmable memory unit makes available an adjustment value that can be set by the one-time programming, which adjustment value is forwarded to the integrated circuit in order to adapt at least one operating parameter in accordance with the adjustment value.

4. The device according to claim 1, embodied as a microphone that supplies an analog output signal, wherein the integrated circuit regulates the operation and the sensitivity of the microphone and also the strength of the output signal, wherein the programmable memory unit makes available an adjustment value that can be set by the programming, which adjustment value is forwarded to the integrated circuit in order to adapt at least one operating parameter in accordance with the adjustment value.

5. The device according to claim 2, wherein exactly three grid areas and thus three soldering locations are provided via which the device can be connected and via which the proper operation of the device is possible, wherein contact areas for ground, supply voltage and for the signal output comprise in three different soldering locations, wherein the contact areas for ground and supply voltage are smaller contact areas and share the grid area with in each case a smaller area contact area for a clock signal and a program signal input, which are connected to the programmable memory unit.

6. The device according to claim 4, wherein exactly three grid areas and thus three soldering locations are provided via which the device can be connected and via which the proper operation of the device is possible, wherein contact areas for ground, supply voltage and for the signal output comprise in three different soldering locations, wherein the contact areas for ground and supply voltage are smaller contact areas and share the grid area with in each case a smaller area contact area for a clock signal and a program signal input, which are connected to the programmable memory unit.

7. The device according to claim 1, wherein the programmable memory unit is a flash memory.

8. The device according to claim 1, wherein all the soldering locations are approximately of identical size.

9. A method for adjusting devices comprising an electromechanical component, a control circuit and a programmable memory unit, comprising the steps of: preparing finished produced devices, determining at least one operating parameter for each of the prepared devices, comparing the determined operating parameters with a predefined setpoint value or setpoint value range for identifying devices deviating therefrom, determining a respective adjustment value for each deviating device, inputting the respective adjustment value into the programmable memory unit via contact areas of the device to be adjusted, wherein the adjustment value can adjust the control circuit of the device such that the deviating operating parameter(s) correspond(s) again to the setpoint value or the setpoint value range, and wherein the devices are soldered after the adjustment value has been input into the programmable memory unit, the soldering locations for each respective one of the devices are arranged in a grid, each of the soldering locations fills a respective grid area, two of the contact areas are smaller contact areas and share one of the soldering locations, the two smaller contact areas are automatically short-circuited during the soldering thereby rendering further influencing or programming of the programmable memory unit impossible without disturbing proper functioning of the respective device, one of the smaller contact areas is configured to be used to carry out one-time programming (OTP) of the electric device during which the respective adjustment value is inputted, an other of the smaller contact areas is configured to be used to carry out the proper functioning of the respective device.

10. The method according to claim 9, wherein all the soldering locations are approximately of identical size.

11. The method according to claim 10, wherein the device is an analog miniaturized microphone with integrated amplifier, said microphone comprising a capacitor having variable capacitance as the electromechanical component, wherein the sensitivity of the microphone is determined as the operating parameter, wherein the adjustment value is provided for varying either the gain of an output signal of the microphone or a BIAS voltage applied to the capacitor of the microphone in order to adjust the sensitivity to the setpoint value or the setpoint value range.

12. The method according to claim 9, wherein the device is an analog miniaturized microphone with integrated amplifier, said microphone comprising a capacitor having variable capacitance as the electromechanical component, wherein the sensitivity of the microphone is determined as the operating parameter, wherein the adjustment value is provided for varying either the gain of an output signal of the microphone or a BIAS voltage applied to the capacitor of the microphone in order to adjust the sensitivity to the setpoint value or the setpoint value range.

Description

(1) The invention is explained in greater detail below on the basis of exemplary embodiments and the associated figures. The figures have been drawn up merely schematically and not in a manner true to scale, and so neither absolute nor relative dimensional indications can be inferred from them. Identical or identically acting parts are designated by identical reference signs.

(2) FIG. 1 shows a plan view of the underside of a microphone comprising the contact areas in the prior art,

(3) FIG. 2 shows the same plan view for a microphone according to the invention,

(4) FIG. 3 shows a schematic cross section through a microphone according to the invention mounted on a circuit carrier.

(5) An analog MEMS microphone is mounted on a carrier TR comprising, on a first surface, designated hereinafter as the underside, three contact areas CA.sub.N of identical size that are arranged in a regular grid. A first contact area VDD serves for supply with a supply voltage, a second contact area GND is provided for the ground connection and a third contact area OUT is intended for the output signal of the microphone.

(6) A sound opening SO toward the electroacoustic transducer, in particular toward an MEMS capacitor microphone, is likewise arranged on the underside of the carrier TR.

(7) At a distance from the contact areas CA.sub.N, a ring-shaped metallization RM is arranged on the underside and is intended for soldering with a likewise ring-shaped connection area on a circuit carrier in order thus to seal the acoustic channel.

(8) As is clearly evident from the figure, the underside of the carrier TR is area-optimized and offers no space for a further contact area CA.sub.N at least in the predefined grid.

(9) On the top side of the carrier TR, which naturally cannot be illustrated in the figure, the abovementioned MEMS capacitor microphone is provided as the electromechanical component, and an ASIC component is provided as the integrated circuit IC, said ASIC component having a region embodied as a programmable memory circuit.

(10) FIG. 2 shows the plan of the underside of a microphone according to the invention. With in principle the same area division and available basic area of the carrier TR, here the first two contact areas CA.sub.S are split, such that here a total of five contact areas are available, four of them having a contact area approximately half the size of that as illustrated before and in FIG. 1. Here in each case two contact areas having a smaller basic area CAS fill the grid area or the space occupied by the larger contact area in the known microphone. However, the divided contact areas are electrically isolated from one another. The newly created smaller contact areas CA.sub.S are provided here for a program signal input W/R, which may also be a write/read access. A further newly created contact area is provided for the clock signal CLK.

(11) A programming of the programmable memory unit, which may be an OTP component, is possible via the two split contact areas, that is to say the four contact areas having a reduced basic area. During the programming, the electrical connection to the now smaller contact areas can be performed by means of point contacts.

(12) It is also possible, however, to clamp the microphone according to the invention, for inputting the adjustment value, into a suitable apparatus with spring contacts. After the contacting of all the contact areas, in the adjustment method according to the invention, operating parameters are determined, in particular the sensitivity of the microphone is determined. The contact areas VDD for supply voltages, GND for ground and OUT for signal output are used for this purpose. The ascertainment of the sensitivity can be carried out for different frequencies and for different signal strengths. Accordingly, the adjustment value can also constitute an extensive set of adjustment values which satisfy the different operating situations of the microphone.

(13) Depending on how the readjustment of the operating parameter is performed with the aid of the adjustment value, the adjustment value is ascertained from the deviations from a setpoint value or from a setpoint value range. After programming the adjustment value into the programmable memory circuit, in which a read-only memory is written to, the microphone is disconnected from the contacts of the measuring and programming station and is now ready for use. The stored adjustment value is stored by the device over a relatively long period of many years and thus over the entire lifetime of the microphone, without an external power supply being required for this purpose.

(14) FIG. 3 shows in schematic cross section a device BE mounted onto a circuit carrier PCB, said device being embodied here as a microphone. The device BE is mounted via soldering connections, for example solder bumps SB. In this case, the contact areas CA on the underside of the carrier TR are connected via soldering connections to corresponding connection areas KF on the top side of the circuit carrier PCB. Furthermore, the ring-shaped metallization MR on the underside of the carrier TR is connected to a likewise ring-shaped metallization on the top side of the circuit carrier PCB by means of a soldering ring SR. The mutual alignment of circuit carrier PCB and device BE is effected such that the sound opening SO in the carrier TR is centered above a corresponding sound hole in the circuit carrier. The sound channel then extends from below through the sound hole in the circuit carrier PCB through the ring-shaped seal SR, the sound opening SO in the carrier TR as far as the microphone EMC, which is illustrated here as an MEMS device with a membrane arranged at the bottom. The MEMS device is fixed on the top side of the carrier TR by means of a flip-chip design.

(15) Between the contact areas on the underside of the carrier TR and the connection areas KF on the top side of the circuit carrier PCB, the electrical contact is produced via three soldering locations SB, which are embodied for example as solder bumps. Each soldering location here completely fills a grid area and here short-circuits in each case two divided or split contact areas CA.sub.S. The device BE is connected via the three soldering locations, wherein a soldering location OUT serves for the signal output. In FIG. 3, the solder contact SB illustrated on the left is led through the small-area or split contact areas for GND and CLK in accordance with the sectional line AA in FIG. 2.

(16) The construction of the microphone as illustrated in FIG. 3 furthermore shows the integrated circuit IC, which is mounted as a semiconductor component on the surface of the carrier, here for example likewise as a flip-chip arrangement. The integrated circuit IC in this case comprises the programmable memory unit, which here constitutes a part of the integrated circuit.

(17) The electromechanical transducer EMC is fabricated from crystalline silicon, for example. Integrated circuit IC and electromechanical transducer EMC are preferably arranged adjacent and sealed with a common cover CV from above in relation to the carrier TR and thus also in relation to harmful environmental influences.

(18) The cover CV may be a cover that bears conformally or is applied as at least one layer, which cover may also be configured in a multilayered fashion. Such a cover may comprise for example a flexible plastic film, which if appropriate is reinforced by means of an inorganic layer, in particular a metal layer. The metal layer can furthermore serve as electromagnetic shielding. However, the cover may also be a preformed rigid cover, for example a metal cap. It is also possible, however, for a trough-shaped depression to be formed on the carrier, the electromechanical transducer EMC being arranged within said depression. The trough may also be formed by a frame structure enclosing the electromechanical transducer EMC on the carrier. The cover may then close the trough like a lid and may be embodied in a planar fashion for this purpose.

(19) Integrated circuit and electromechanical transducer EMC are electrically connected to one another, wherein the connection can be performed via an integrated interconnection within the carrier TR. It is also possible to interconnect integrated circuit and electromechanical transducer EMC via conductor tracks that are led on the surface of the carrier TR. A direct connection of the integrated interconnection and of the electromechanical transducer EMC by means of wires is also possible.

(20) The volumes between electromechanical transducer EMC and carrier and also the volume between the integrated circuit IC and the carrier TR can be connected to one another. The volume above the membrane and the cover CV constitutes the back volume of the electromechanical transducer.

(21) Besides an application of the invention for an MEMS microphone, the invention is suitable for further electromechanical sensors which, on account of their miniaturization, have an optimized footprint that can be reduced only with difficulty. Electromechanical components are affected in particular by manufacturing fluctuations, such that with the invention there is a simple possibility of readjusting fluctuations of the operating parameters that occur within a manufacturing batch, and thus of obtaining devices having uniform operating parameters or having only small manufacturing tolerances. According to the invention, this can be done without increasing the basic area of the devices and without altering the design for the user.

(22) The invention is also not restricted to the embodiments illustrated in the figures. In particular, a device can comprise a larger number of contact areas; likewise, the contact areas can be distributed over a carrier differently than illustrated or have a different form.

(23) It is also possible for exclusively contact areas to be provided on the underside of the carrier, wherein then in the case of a microphone, for example, a sound opening facing upward is provided, which no longer requires an opening in the carrier TR.

LIST OF REFERENCE SIGNS

(24) BE Electric device TR Carrier OF1 First surface Grid having number of grid areas CA.sub.N,S Contact areas EMC Electromechanical component IC Integrated circuit SB Soldering locations CA.sub.S Smaller-area contact areas, share a grid area PCB Circuit carrier SO Sound opening CV Cover RM Ring-shaped metallization for SR Solder frame KF Connection areas on PCB M Membrane