Cost-efficient fingerprint sensor component and manufacturing method

A method of manufacturing a fingerprint sensor component having a component outline for integration into an electronic device, the method comprising the steps of: providing a fingerprint sensor package having a sensing surface, a connection surface opposite the sensing surface, and sides connecting the sensing surface and the connection surface, the connection surface having connectors for allowing electrical connection of the fingerprint sensor component to the electronic device; arranging the fingerprint sensor package on a temporary carrier with the connection surface facing the temporary carrier; and adding material at least around the sides of the fingerprint sensor package, while leaving the connection surface of the fingerprint sensor package uncovered.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 371 U.S. National Stage of International Application No. PCT/SE2018/051177, filed Nov. 15, 2018, which claims priority to Swedish Patent Application No. 1751447-2, filed Nov. 24, 2017. The disclosures of each of the above applications are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to a fingerprint sensor component for integration in an electronic device, and to a method of manufacturing such a fingerprint sensor component.

BACKGROUND OF THE INVENTION

Biometric systems are widely used as means for increasing the convenience and security of personal electronic devices, such as mobile phones etc. Fingerprint sensing systems, in particular, are now included in a large proportion of all newly released personal communication devices, such as mobile phones.

Fingerprint sensors are often included in a user-interaction device, such as a button or similar in the housing of the electronic device.

With the recent development of improved fingerprint sensors and biometric algorithms, smaller fingerprint sensors can be integrated in the above-mentioned user-interaction devices.

The use of smaller fingerprint sensors provides for a cost reduction of the fingerprint sensing systems. It would, however, be desirable to provide for a further reduction of the cost.

SUMMARY

In view of above-mentioned and other drawbacks of the prior art, it is an object of the present invention to provide for improved fingerprint sensor components, in particular more cost-efficient fingerprint sensor components.

According to a first aspect of the present invention, it is therefore provided a method of manufacturing a fingerprint sensor component having a component outline for integration into an electronic device, the method comprising the steps of: providing a fingerprint sensor package having a sensing surface, a connection surface opposite the sensing surface, and sides connecting the sensing surface and the connection surface, the connection surface having connectors for allowing electrical connection of the fingerprint sensor component to the electronic device; arranging the fingerprint sensor package on a temporary carrier with the connection surface facing the temporary carrier; and adding material at least around the sides of the fingerprint sensor package, while leaving the connection surface of the fingerprint sensor package uncovered.

It should be understood that the electronic device into which the fingerprint sensor component is intended to be integrated may, for example, be a personal communication device, or a token, such as a so-called smart card etc. Alternatively, the electronic device may be a fingerprint sensor module to be included in another electronic device.

The temporary carrier may be any carrier suitable for the fabrication process, and may include any carrier used in so-called wafer level fan-out processes, or in panel production processes (such as for thin film electronics). The temporary carrier may, for example, include a relatively rigid base covered by a temporary bond film (carrier tape). The relatively rigid base may be made of any material compatible with the particular fabrication process, and may thus, for instance, be made of silicon, glass, polymer or metal. Alternatively, the temporary carrier may be a carrier tape.

It should be noted that the steps of methods according to embodiments of the present invention need not necessarily be carried out in any particular order, unless explicitly or implicitly required.

The present invention is based upon the realization that it may be considerably more cost-efficient to re-package to a desired component outline an already packaged small fingerprint sensor, than to package the small fingerprint sensor to the desired component outline in a single packaging process. In particular, the present inventor has realized that the “re-packaging” according to embodiments of the present invention allows relatively costly process steps (initial packaging of integrated circuit (IC) dies) to be performed on densely arranged small fingerprint sensors, while less costly process steps (post processing of already packaged IC dies) can be performed on less densely arranged fingerprint sensor packages.

According to embodiments of the present invention, the size reduction of the fingerprint sensor ICs can thus be exploited more efficiently to achieve increased cost-reductions for the fingerprint sensor components with (lateral) component outlines suitable for the electronic devices into which the fingerprint sensor components are to be integrated. Such component outlines may typically be specified by the manufacturers of the electronic devices to harmonize with the designs of the electronic devices and/or to provide for advantageous user interaction with the electronic devices.

In embodiments, the step of adding material may comprise the step of applying a dielectric material to cover at least the sides of the fingerprint sensor package.

The dielectric material covering at least the sides of the fingerprint sensor package may, as will be known to one skilled in the art, be any dielectric embedding material suitable for the particular fabrication process. Accordingly, the dielectric material may be a non-conducting adhesive, or a molding material that may, for example be provided in granular or liquid form. Alternatively, the dielectric material may be provided in the form of a film that is laminated on the fingerprint sensor package(s) arranged on the temporary carrier. The dielectric material may be cured following application.

The dielectric material may be applied to cover the sides and the sensing surface of the fingerprint sensor package; and the method may further comprise the step of at least partly removing the dielectric material, at least over the fingerprint sensor package.

The dielectric material may be at least partly removed in such a way that a planar and smooth upper surface of the fingerprint sensor component(s) is formed by the removal process. Various material removal methods that are, per se, well known include grinding, polishing/lapping, and etching.

A sufficient thickness of the dielectric material may advantageously be removed to expose the sensing surface of the fingerprint sensor package.

In embodiments, while the dielectric material is at least partly removed, the fingerprint sensor package may be thinned down in such a way that a new sensing surface is formed. In other words, the fingerprint sensor package comprised in the fingerprint sensor component may be thinned in the same process used for at least partly removing the applied dielectric material.

These embodiments may allow for improved sensitivity of the fingerprint sensor component and/or allow for more cost-efficient manufacturing methods to be used when making the fingerprint sensor package(s), since the important thickness of the protective coating on the fingerprint sensor IC in the fingerprint sensor package/fingerprint sensor component can be defined by the material removal step in embodiments of the method according to the present invention.

According to various embodiments, the step of adding material at least around the sides of the fingerprint sensor package may comprises the step of: arranging at least one spacing member on the temporary carrier to at least partly surround the fingerprint sensor package.

It should be noted that the at least one spacing member may be arranged on the temporary carrier before or after the step of arranging the fingerprint sensor package(s) on the temporary carrier. The at least one spacing member may, for example, be made of plastic or laminate. The at least one spacing member may simultaneously perform the functions of cost-efficiently providing for the desired fingerprint sensor component outline, and aiding in the positioning of the fingerprint sensor package(s) on the temporary carrier.

The at least one spacing member may advantageously comprise a frame surrounding said fingerprint sensor package (or surrounding each fingerprint package in embodiments where a plurality of fingerprint packages are arranged mutually laterally spaced apart on the temporary carrier).

In embodiments where at least one spacing member is arranged on the temporary carrier to surround the fingerprint sensor package(s), a non-conductive adhesive may be dispensed in the space between the fingerprint sensor package(s) and the spacing member(s).

In embodiments without the provision of at least one spacing member on the temporary carrier, the fingerprint sensor package(s) may be overmolded using, per se, known molding processes, such as transfer molding or compression molding. Also in embodiments including the provision of at least one spacing member on the temporary carrier, the fingerprint sensor package(s) and the spacing member(s) may be overmolded.

The method according embodiments of the present invention may further comprise the step of removing material around the fingerprint sensor package in such a way that the component outline is achieved.

Such material removal may, for example, be achieved using mechanical sawing or scribing, laser cutting, water jet cutting, and etching etc.

Advantageously a large number of fingerprint sensor packages may be arranged on the temporary carrier, material may be added around each fingerprint sensor package using any of the different processes described above or a combination thereof to form a panel or so-called strip, and the panel or strip may be cut (preferably using one of the above-describe methods of removing dielectric material) to separate the panel or strip into fingerprint sensor components having the desired component outline.

As an alternative to removing material to achieve the desired component outline, the material may be added around the fingerprint sensor package(s) in such a way that the component outline is achieved. This may, for example be achieved using a mold with one or several mold cavities shaped in accordance with the desired component outline.

According to various embodiments, furthermore, the fingerprint sensor package may comprise: a package substrate having a die support side and an external connection side opposite the die support side; a fingerprint sensor die electrically and mechanically connected to the die support side of the package substrate; and a protective coating covering the fingerprint sensor die and the package substrate, the connectors of the fingerprint sensor package being arranged on the external connection side of the package substrate.

According to a second aspect of the present invention, there is provided a fingerprint sensor component having a component outline for integration into an electronic device, the fingerprint sensor component comprising: a fingerprint sensor package having a sensing surface, a connection surface opposite the sensing surface, and sides connecting the sensing surface and the connection surface, the connection surface having connectors for allowing electrical connection of the fingerprint sensor component to the electronic device, the fingerprint sensor package having a fingerprint sensor package outline, different from the component outline; and material added at least around the sides of the fingerprint sensor package, while leaving the connection surface of the fingerprint sensor package uncovered, the material defining the component outline of the fingerprint sensor component.

Moreover, the fingerprint sensor component according to various embodiments of the present invention may advantageously be included in an electronic device, further comprising processing circuitry electrically coupled to the fingerprint sensor component through the connectors on the connection surface of the fingerprint sensor package comprised in the fingerprint sensor component.

Further embodiments of, and effects obtained through this second aspect of the present invention are largely analogous to those described above for the first aspect of the invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

In the present detailed description, various embodiments of the fingerprint sensor component according to the present invention are mainly described with reference to a fingerprint sensor component including a semiconductor-based capacitive fingerprint sensor integrated circuit (IC). It should be noted that fingerprint sensor components comprising other types or configurations of fingerprint sensors also fall within the scope defined by the claims. For instance, the fingerprint sensor comprised in the fingerprint sensor component may sense the fingerprint of a finger placed on the sensor using one or several other measurement principles, such as ultrasonic, thermal, or optical measurement.

FIG. 1schematically shows an electronic device, here in the form of a mobile phone1, comprising a fingerprint sensor module3, including fingerprint sensor component according to embodiments of the present invention. The fingerprint sensor component may be included in the fingerprint sensor module3that is integrated into the mobile phone1, or may be directly integrated into the mobile phone1. In either case, the sensing side of the fingerprint sensor component may be on the back face of the mobile phone1as in the example ofFIG. 1, or on the front face, or on a side face of the mobile phone1.

FIG. 2schematically illustrates an example fingerprint sensor module3that may be comprised in the mobile phone1inFIG. 1. Referring toFIG. 2, the fingerprint sensor module3comprises the above-mentioned fingerprint sensor component5, which includes a fingerprint sensor IC7(schematically indicated by the dashed line box inFIG. 2), a power supply modulation IC9, and a flex film connector11for allowing electrical connection between the fingerprint sensor component5and the electronic device (mobile phone1) in which the fingerprint sensor component5is included.

The power supply modulation IC9may modulate the reference potential(s) of the fingerprint sensor IC7in relation to the reference potential(s) of the electronic device1as is described in, for example, U.S. Pat. No. 9,383,876.

FIG. 3Aschematically shows the fingerprint sensor component5inFIG. 2from the fingerprint sensing side13of the fingerprint sensor component5(top), and from the connector side15of the fingerprint sensor component (bottom).

Referring toFIG. 3A, the fingerprint sensor component5comprises a fingerprint sensor package17having a sensing surface19, a connection surface21opposite the sensing surface19, and sides23connecting the sensing surface19and the connection surface21. The connection surface21has connectors25for allowing electrical connection of the fingerprint sensor component5to the rest of the electronic device (mobile phone1). In addition to the fingerprint sensor package17, the fingerprint sensor component5comprises material27added at least around the sides23of the fingerprint sensor package17, and an optional dielectric top coating29covering both the above-mentioned material27and the sensing surface19of the fingerprint sensor package17. As can be understood by studyingFIG. 3A, the component outline suitable for the electronic device1(here a round shape) has been achieved using the material27added at least around the sides of the fingerprint sensor package17.

As will be described in greater detail below with reference toFIG. 3BandFIG. 3C, the fingerprint sensor package17includes the above-mentioned fingerprint sensor IC7, which is covered by a protective coating31, as is schematically indicated inFIG. 3A.

FIG. 3Bis a schematic view of the cross-section along the line A-A′ inFIG. 3Aof a first embodiment of the fingerprint sensor component5inFIG. 3A, in which the material27added at least around the sides23of the fingerprint sensor package17is provided in the form of a cured molding compound. For simplicity, the cross-section inFIG. 3Bis shown without the optional dielectric top coating29inFIG. 3A.

As is schematically shown inFIG. 3B, the fingerprint sensor package17included in the fingerprint sensor component5comprises a package substrate33having a die support side35and an external connection side37opposite the die support side35. The package substrate includes die connection pads39on the die support side35, and vias41for electrical connection between the die connection pads39and the connectors25on the external connection side37of the package substrate33.

Referring toFIG. 3B, the fingerprint sensor die7is attached to the die support side35of the package substrate33, and connection pads43on the fingerprint sensor die7are electrically connected to the die connection pads39, here through bond wires46.

FIG. 3Cis a schematic view of the cross-section along the line A-A′ inFIG. 3Aof a second embodiment of the fingerprint sensor component5inFIG. 3A, in which the material27added at least around the sides23of the fingerprint sensor package17is provided in the form of a plastic frame45surrounding the fingerprint sensor package17, and adhesive47in the gap between the fingerprint sensor package17and the plastic frame45.

Although it is indicated inFIGS. 3A-Cthat the fingerprint sensor IC7is electrically connected to the package substrate33using bond wires46, it should be understood that this electrical connection may be made using any other suitable connection technique, such as using conductive vias through the fingerprint sensor IC7and pads or bumps on the backside of the fingerprint sensor IC7etc. Furthermore, the package substrate33need not be a substrate of circuit board type as is schematically indicated here, but may, for example, be a metal substrate, such as a so-called leadframe or similar.

A method according to a first embodiment of the present invention of manufacturing the fingerprint sensor component5inFIG. 3Bwill now be described with reference to the flow-chart inFIG. 4, and the accompanying illustrations inFIGS. 5A-D.

In a first step401, a plurality of fingerprint sensor packages17are arranged on a carrier tape49with an adhesive layer for keeping the fingerprint sensor packages17in place during the subsequent processing. This is schematically illustrated inFIG. 5A.

Thereafter, in step402, the fingerprint sensor packages17arranged on the carrier tape49are covered by a dielectric material27.

The dielectric material27may, as will be known to one skilled in the art, be any dielectric embedding material suitable for the particular fabrication process. Accordingly, the dielectric material may be a molding material that may, for example be provided in granular or liquid form. Alternatively, the dielectric material may be provided in the form of a film that is laminated on the fingerprint sensor packages17arranged on the carrier tape49.

In the subsequent step403, some of the dielectric material27added in step402is removed by thinning the fingerprint sensor package panel51from the top side thereof, as is schematically indicated inFIG. 5C. Advantageously, the fingerprint sensor package panel51may be thinned sufficiently far to at least expose the sensing surface of each fingerprint sensor package17. In embodiments, it may be advantageous to continue the thinning process so that the fingerprint sensor package17is thinned down in such a way that a new sensing surface is formed. Various thinning methods that are, per se, well known include grinding, polishing/lapping, and etching.

After this step, a panel or so-called strip53has been formed, which may include hundreds of re-packaged fingerprint sensor packages17. In embodiments, the manufacturing method may end here, and the strip53may be delivered for further processing at another facility.

Optionally, the strip may be divided, in step404, by cutting through the dielectric material27between adjacent fingerprint sensor packages17to form a plurality of separated fingerprint sensor components5. This is schematically shown inFIG. 5D. It should be understood that the strip may be divided while arranged on the carrier tape49, or following debonding from the carrier tape49.

A method according to a second embodiment of the present invention of manufacturing the fingerprint sensor component5inFIG. 3Cwill now be described with reference to the flow-chart inFIG. 6, and the accompanying illustrations inFIGS. 7A-D.

In a first step601, a plurality of fingerprint sensor packages17are arranged, together with at least one frame45surrounding the fingerprint sensor packages17, on a carrier tape49with an adhesive layer for keeping the fingerprint sensor packages17in place during the subsequent processing. This is schematically illustrated inFIG. 7A. It should be understood that a plurality of frames may be provided, such as one frame for each fingerprint sensor package17. Advantageously, however, one frame45may have openings for a plurality of fingerprint sensor packages17. Either of the frame(s)45and the fingerprint sensor packages17may first be arranged on the carrier49. It may be advantageous to first arrange a frame45with openings for a plurality of fingerprint sensor packages17, and then place the fingerprint sensor packages17in the openings.

Thereafter, in step602, a suitable dielectric material, such as an adhesive47is dispensed to fill the gaps between the frame45and the fingerprint sensor packages17.

In the subsequent step403, some of the frame45and adhesive47is removed by thinning the fingerprint sensor package panel51from the top side thereof, as is schematically indicated inFIG. 7C. Advantageously, the fingerprint sensor package panel51may be thinned sufficiently far to at least expose the sensing surface of each fingerprint sensor package17. In embodiments, it may be advantageous to continue the thinning process so that the fingerprint sensor package17is thinned down in such a way that a new sensing surface is formed. Various thinning methods that are, per se, well known include grinding, polishing/lapping, and etching.

After this step, a panel or so-called strip53has been formed, which may include hundreds of re-packaged fingerprint sensor packages17. In embodiments, the manufacturing method may end here, and the strip53may be delivered for further processing at another facility.

Optionally, the strip may be divided, in step604, by cutting through the frame45between adjacent fingerprint sensor packages17to form a plurality of separated fingerprint sensor components5. This is schematically shown inFIG. 7D. It should be understood that the strip may be divided while arranged on the carrier tape49, or following debonding from the carrier tape49.