JP6942211B2 - Measurement sensor package and measurement sensor - Google Patents

Description

The present invention relates to a measurement sensor package and a measurement sensor.

There is a demand for a measurement sensor that can easily and quickly measure biological information such as blood flow. For example, blood flow can be measured using the Doppler effect of light. When blood is irradiated with light, the light is scattered by blood cell cells such as red blood cells. The moving speed of blood cell cells is calculated from the frequency of the irradiation light and the frequency of the scattered light.

A measurement sensor that measures blood flow is described as, for example, a self-luminous measurement sensor in Patent Document 1, and an irradiation unit that irradiates blood with light and a light receiving unit that receives scattered light are arranged on a substrate. , The front plate on which the exit port for passing the irradiation light from the irradiation part and the incident port for passing the scattered light from the blood are formed by the light-shielding adhesive portion surrounding each is adhered to the substrate. There is.

Japanese Patent No. 5031895

In the conventional measurement sensor, since both the irradiation unit and the light receiving unit are arranged on the same surface of the substrate, crosstalk is likely to occur between the irradiation unit side and the light receiving unit side, and high-precision measurement is performed. Was difficult.

The package for a measurement sensor according to one aspect of the present invention is a rectangular plate-shaped substrate in which a plurality of dielectric layers are laminated, and has a first accommodating recess accommodating a light emitting element and a second accommodating a light receiving element. The accommodating recess is provided on one main surface, the first accommodating recess includes a first bottom surface on which the light emitting element is mounted, and the second accommodating recess includes a second bottom surface on which the light receiving element is mounted. It is characterized in that the depth of the first accommodating recess includes a substrate shallower than the depth of the second accommodating recess.

Further, the measurement sensor according to one aspect of the present invention includes the above-mentioned measurement sensor package and the above-mentioned package for the measurement sensor.
The light emitting element accommodated in the first accommodating recess and
It is characterized by including a light receiving element accommodated in the second accommodating recess.

According to the measurement sensor package of one aspect of the present invention, crosstalk between the light emitting element side and the light receiving element side can be reduced.

Further, according to the measurement sensor of one aspect of the present invention, by providing the above-mentioned package for the measurement sensor, highly accurate measurement becomes possible.

It is a top view which shows the package 1 for the measurement sensor which concerns on embodiment of this invention. It is sectional drawing which cut at the cut plane line AA of FIG. It is sectional drawing which cut at the cut plane line BB of FIG. FIG. 5 is a cross-sectional view of a measurement sensor package 1A corresponding to the cross-sectional view shown in FIG. FIG. 3 is a cross-sectional view of a measurement sensor package 1A corresponding to the cross-sectional view shown in FIG. It is sectional drawing which shows the structure of the measurement sensor 100. It is a figure which shows the simulation result of the amount of crosstalk in an Example and a comparative example. It is a figure which shows the evaluation result of an Example and a comparative example.

FIG. 1 is a plan view showing a measurement sensor package 1 according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the cutting plane line AA of FIG. 1, and FIG. 3 is FIG. It is sectional drawing which cut at the cut plane line BB of. In the plan view of FIG. 1, the lid 3, the ground conductor layer 4, and the signal wiring conductor 23 are omitted.

The measurement sensor package 1 includes a base 2 that houses a light emitting element and a light receiving element.

The substrate 2 of the present embodiment has a rectangular plate shape, and is formed by laminating a plurality of dielectric layers. Further, the substrate 2 is provided with at least two recesses, one of the two recesses is a first accommodating recess 20a for accommodating a light emitting element, and the other of the two recesses receives light. A second accommodating recess 20b for accommodating the element. The first accommodating recess 20a and the second accommodating recess 20b are provided so as to open to one main surface 20c of the substrate 2.

The measurement sensor package 1 of the present embodiment is suitably used for a measurement sensor that measures the flow of a fluid such as blood flow by utilizing the Doppler effect of light. In order to utilize the Doppler effect of light, the measurement sensor includes a light emitting element that irradiates the object to be measured with light and a light receiving element that receives the light scattered by the object to be measured. In particular, when measuring blood flow, for example, a part of the body such as a finger is irradiated with light from the outside, and the light scattered by blood cell cells contained in the blood flowing through the blood vessels under the skin is received to receive the frequency. Blood flow is measured from the change in. Therefore, in the measurement sensor package 1, the light emitting element and the light receiving element are arranged at a predetermined interval based on the positional relationship between the irradiation light and the scattered light. The first accommodating recess 20a and the second accommodating recess 20b are provided according to the positional relationship of the elements.

In the present embodiment, the first accommodating recess 20a includes a first bottom surface 20d on which a light emitting element is mounted, and the second accommodating recess 20b includes a second bottom surface 20e on which a light receiving element is mounted. The depth d1 of the first accommodating recess 20a is shallower than the depth d2 of the second accommodating recess 20b. For example, d1 is 0.3 mm to 1.0 mm and d2 is 0.4 mm to 1.5 mm.

By providing such a first accommodating recess 20a and a second accommodating recess 20b, the light emitting element mounted on the first bottom surface 20d and the light receiving element mounted on the second bottom surface 20e are on one main surface of the substrate 2. Not only are they separated in the plane direction of 20c, but they are also separated in the thickness direction of the substrate 2.

In the measurement sensor provided with the measurement sensor package 1 of the present embodiment, a sufficient distance is secured between the light emitting element and the light receiving element in both the surface direction of one main surface 20c of the base 2 and the thickness direction of the base 2. This makes it possible to reduce crosstalk between the light emitting element side and the light receiving element side, and enable highly accurate measurement.

The measurement sensor package 1 of the present embodiment further includes a lid 3 and a ground conductor layer 4.

The lid 3 is joined to one main surface 20c of the substrate 2 to cover the first accommodating recess 20a and the second accommodating recess 20b. The lid 3 is a plate-shaped member made of an insulating material, and light emitted from a light emitting element accommodated in the first accommodating recess 20a is transmitted and received by a light receiving element accommodated in the second accommodating recess 20b. It is configured to allow light to pass through.

In the measurement sensor provided with the measurement sensor package 1 of the present embodiment, the surface of the lid 3 is irradiated with the light emitted from the light emitting element with, for example, a finger as an object to be measured. When the lid 3 is made of a conductive material, when the fingers are brought into contact with the lid 3, unnecessary charges accumulated on the fingertips are released from the fingers and charged to the substrate 2 through the lid 3. Will flow in and noise will be generated. By forming the lid 3 with an insulating material, it is possible to prevent unnecessary charges from flowing through the lid 3.

Further, the lid 3 needs to transmit the irradiation light and the scattered light to the object to be measured. Since the characteristics of the irradiation light and the scattered light are determined by the light emitting element to be mounted, at least the light emitted by the light emitting element to be mounted may be configured to be transmitted. The lid 3 may be made of an insulating material having a transmittance of 70% or more, preferably 90% or more of the light having a wavelength of the light emitted from the light emitting element.

As the insulating material constituting the lid 3, for example, a transparent ceramic material such as sapphire, a glass material, a resin material, or the like can be used. As the glass material, borosilicate glass, crystallized glass, quartz, soda glass and the like can be used. As the resin material, a polycarbonate resin, an unsaturated polyester resin, an epoxy resin, or the like can be used.

The lid 3 requires a predetermined strength because it comes into direct contact with an object to be measured such as a finger. The strength of the lid 3 depends on the strength of the constituent materials and the plate thickness. If it is a transparent ceramic material or a glass material as described above, sufficient strength can be obtained by setting the thickness to a predetermined value or more. When a glass material is used as the constituent material of the lid 3, for example, the thickness may be 0.05 mm to 5 mm.

The ground conductor layer 4 is arranged on the main surface of the lid 3 on the side facing the first accommodating recess 20a and the second accommodating recess 20b, that is, on the main surface opposite to the main surface on the side with which the fingers come into contact. , Connected to the ground potential. The ground conductor layer 4 is provided with a first opening 4a through which the light emitted from the light emitting element passes and a second opening 4b through which the light received by the light receiving element passes.

The ground conductor layer 4 has a first opening 4a and a second opening 4b so that unnecessary light does not emit to the outside from the first accommodating recess 20a and unnecessary light does not enter the second accommodating recess 20b from the outside. It functions as a provided mask member.

Further, the ground conductor layer 4 also functions as an electromagnetic shield for suppressing electromagnetic waves arriving from the outside from entering the first accommodating recess 20a and the second accommodating recess 20b. When an electromagnetic wave enters the first accommodating recess 20a and the second accommodating recess 20b, for example, the bonding wire that electrically connects the measurement sensor package 1 with the light emitting element and the light receiving element acts as an antenna to receive the entering electromagnetic wave. This will cause noise. By providing the ground conductor layer 4 on the main surface of the lid 3 except for the first opening 4a and the second opening 4b for passing light, it is possible to suppress the ingress of electromagnetic waves and reduce the generation of noise. can.

By providing the grounding conductor layer 4 on the lid 3 in this way, the influence of noise can be suppressed and the measurement accuracy can be improved.

The ground conductor layer 4 is formed on the surface of a lid 3 made of a transparent ceramic material or a glass material, for example, Cr, Ti, Al, Cu, Co, Ag, Au, Pd, Pt, Ru, Sn, Ta, Fe, In. , Ni, W and other metals and metal materials such as alloys thereof can be formed as a metal thin film by vapor deposition, sputtering, baking or the like. The layer thickness of the ground conductor layer 4 is, for example, 500 Å to 4000 Å.

According to the measurement sensor provided with the measurement sensor package 1 of the present embodiment, the light emitting element can be arranged close to the first opening 4a, and a sufficient distance is provided between the light receiving element and the second opening 4b. Can be secured. As a result, it is possible to prevent the light emitted from the light emitting element from being excessively shielded by the ground conductor layer 4, and the light receiving element is arranged so as to receive only the scattered light incident in a predetermined angle range. Can be done. Therefore, according to the measurement sensor provided with the measurement sensor package 1 of the present embodiment, highly efficient and highly accurate measurement becomes possible.

The opening shape of the first accommodating recess 20a and the second accommodating recess 20b may be, for example, a circular shape, a square shape, a rectangular shape, or the like, or may have other shapes. The first accommodating recess 20a and the second accommodating recess 20b may have a uniform cross-sectional shape in the depth direction in a cross section parallel to the main surface of the substrate 2, but at a predetermined depth, the cross-sectional shape may be uniform. It may be a recess with a step, which is the same as the opening shape and is uniform, and after a predetermined depth, the cross-sectional shape is small and uniform to the bottom.

The size of the first accommodating recess 20a and the size of the second accommodating recess 20b may be appropriately set according to the sizes of the light emitting element and the light receiving element to be accommodated. When a light emitting laser element (VCSEL) is used, the opening of the first accommodating recess 20a may have a rectangular shape or a square shape, for example. The opening of the first accommodating recess 20a has, for example, a vertical length of 0.3 mm to 1.5 mm and a horizontal length of 0.3 mm to 2.0 mm. When a surface-incident photodiode is used as the light receiving element, the opening of the second accommodating recess 20b may have a rectangular shape or a square shape, for example. The size of the second accommodating recess 20b is, for example, 0.5 mm to 2.0 mm in the vertical direction and 0.5 mm to 2.5 mm in the horizontal direction.

In the present embodiment, as shown in the cross-sectional view of FIG. 3, a first stepped portion 20h having a first stepped surface 20f extending in the surface direction of the main surface 20c is provided on the inner surface of the first accommodating recess 20a. On the inner surface of the second accommodating recess 20b, a second step portion 20i having a second step surface 20g extending in the surface direction of the main surface 20c is provided. A first connection pad 23a that is electrically connected to the light emitting element is arranged on the first step surface 20f, and a second connection pad 23b that is electrically connected to the light receiving element is arranged on the second step surface 20g. Arranged. The first connection pad 23a may be arranged on the entire surface or only a part of the first step surface 20f, and the second connection pad 23b may be arranged on the entire surface of the second step surface 20g. It may be arranged only in a part. In the present embodiment, the first connection pad 23a is arranged on substantially the entire surface of the first step surface 20f, and the second connection pad 23b is arranged on substantially the entire surface of the second step surface 20g.

By providing such a first connection pad 23a and a second connection pad 23b, the measurement sensor package 1 and the light emitting element and the light receiving element can be easily and electrically connected by, for example, a bonding wire.

In order to reduce the size of the measurement sensor package 1, it is desirable to reduce the areas of the first step surface 20f and the second step surface 20g, but the connection that electrically connects the light emitting element and the first connection pad 23a. In order to facilitate processing, the deeper the depth of the first accommodating recess 23a, the deeper the depth of the first stepped surface 20f in the thickness direction of the substrate 2, and the larger the area of the first stepped surface 20f. Is desirable. Similarly, in order to easily perform the connection process for electrically connecting the light receiving element and the second connection pad 23b, the deeper the depth of the second accommodating recess 23b, the second stepped surface in the thickness direction of the substrate 2. It is desirable to increase the depth of 20 g and increase the area of the second stepped surface 20 g. As described above, in order to perform high-precision measurement, it is desirable that the depth of the first accommodating recess 20a is shallower than the depth of the second accommodating recess 20b. Therefore, in the present embodiment, the first stepped surface 20f The area of is smaller than the area of the second stepped surface 20 g.

The shapes of the first stepped surface 20f and the second stepped surface 20g may be, for example, a square shape, a rectangular shape, or any other shape. The size of the first stepped surface 20f is, for example, 0.3 mm to 1.5 mm in the vertical direction and 0.1 mm to 1.0 mm in the horizontal direction. The size of the second stepped surface 20 g is, for example, a vertical length of 0.5 mm to 2.0 mm and a horizontal length of 0.2 mm to 1.5 mm. The shapes of the first connection pad 23a and the second connection pad 23b may be, for example, a square shape, a rectangular shape, or any other shape. The size of the first connection pad 23a is, for example, 0.1 mm to 1.5 mm in the vertical direction and 0.1 mm to 1.0 mm in the horizontal direction. The second connection pad 23b has, for example, a vertical length of 0.2 mm to 2.0 mm and a horizontal length of 0.1 mm to 1.5 mm.

In a measurement sensor used for measuring blood flow or the like, the electric signal transmitted through the signal conductor is relatively weak, and is greatly affected by the parasitic capacitance generated inside the measurement sensor. For example, the difference between the parasitic capacitance generated on the light emitting element side and the parasitic capacitance generated on the light receiving element side causes deterioration of measurement accuracy. In the present embodiment, depending on the surface area of the first connection pad 23a and the surface area of the second connection pad 23b in a plan view, between the first connection pad 23a and the ground conductor layer 4 in the thickness direction of the substrate 2. By setting the distance h1 and the distance h2 between the second connection pad 23b and the ground conductor layer 4, the parasitic capacitance formed between the ground conductor layer 4 and the first connection pad 23a and the ground conductor layer The difference between the parasitic capacitance formed between the 4 and the second connection pad 23b is reduced, and the deterioration of the measurement accuracy is suppressed. For example, h1 is 0.05 mm to 0.7 mm and h2 is 0.1 mm to 1.2 mm.

In a measurement sensor used for measuring blood flow, etc., the amount of light received by the light receiving element is relatively small, and the light receiving signal output from the light receiving element is weak. The mixed electrical crosstalk causes noise. In particular, since the connection pad for electrically connecting the measurement sensor package and the light receiving element usually has a large surface area, electromagnetic waves generated from the drive signal of the light emitting element easily enter. In the present embodiment, as shown in FIG. 1, in a plan view, the first step surface 20f on which the first connection pad 23a is arranged in the direction connecting the center of the first bottom surface 20d and the center of the second bottom surface 20e. Since the second stepped surface 20g on which the second connection pad 23b is arranged is arranged on the outside, the measurement sensor provided with the measurement sensor package 1 of the present embodiment receives electromagnetic waves generated from the drive signal of the light emitting element. It is possible to suppress electrical crosstalk mixed in the light receiving signal of the light receiving element.

Further, in the present embodiment, as shown in FIG. 1, the first bottom surface 20d on which the light emitting element is mounted is the first bottom surface 20d in the direction connecting the center of the first bottom surface 20d and the center of the second bottom surface 20e in a plan view. Since the second bottom surface 20e, which is arranged inward of the one stepped surface 20f and on which the light receiving element is mounted, is arranged inward of the second stepped surface 20g, the measurement sensor package 1 of the present embodiment is provided. According to the measurement sensor, the degree of freedom of the distance between the light emitting element and the first opening 4a and the degree of freedom of the distance between the light receiving element and the second opening 4b can be improved, thereby the measurement. Efficiency and accuracy can be further improved.

Further, in the self-luminous measurement sensor, the light emitted from the light emitting element is scattered by the object to be measured, and the shorter the optical path length to reach the light receiving element, the more the light is scattered from the object to be received by the light receiving element. The amount of light increases. In the measurement sensor including the measurement sensor package 1 of the present embodiment, since the light emitting element and the light receiving element are arranged inward, the optical path length between the light emitting element and the light receiving element is shortened, and the sensitivity of the measurement sensor is shortened. Can be improved.

Further, in the measurement sensor provided with the measurement sensor package 1 of the present embodiment, a light-shielding wall having a sufficient thickness for blocking light is provided between the light-emitting element and the light-receiving element when viewed in a plan view, and the light-emitting element and the light-emitting element. Since the structure is such that the light receiving element is arranged close to the light shielding wall, it is possible to suppress optical crosstalk caused by the light receiving element directly receiving the light of the light emitting element.

In this embodiment, the substrate 2 further includes a ground via conductor 21. The grounding via conductor 21 is arranged outside the first accommodating recess 20a and the second accommodating recess 20b of the substrate 2 in a plan view, and is connected to the earth potential. The grounding via conductor 21 is composed of a plurality of through conductors penetrating each dielectric layer constituting the substrate 2 in the thickness direction in a row in the thickness direction of the substrate 2. In the present embodiment, the grounding via conductor 21 penetrates the entire substrate 2 in the thickness direction, as shown in FIG. 2, for example, and in a plan view, the positions of the penetrating conductors provided in each dielectric layer are the same. .. That is, the grounding via conductor 21 penetrates straight from one main surface 20c of the substrate 2 to the other main surface, and one end surface 21a of the grounding via conductor 21 is exposed on one main surface 20c of the substrate 2. The other end surface 21b is exposed on the other main surface of the substrate 2.

One end surface 21a of the grounding via conductor 21 is connected to the grounding conductor layer 4 arranged on the lid 3 via the annular grounding conductor layer 22 described later. The other end surface 21b of the ground via conductor 21 is connected to an external connection terminal 24 arranged on the other main surface of the substrate 2. By such a grounding via conductor 21, the grounding conductor layer 4, the annular grounding conductor layer 22, and the grounding via conductor 21 arranged on the lid 3 are electrically connected and the same grounding potential is given.

By providing such a grounded via conductor 21, when the blood flow is measured by the measurement sensor provided with the measurement sensor package 1, it is released when a person's finger, which is one of the objects to be measured, comes into contact with the measurement sensor. The electric charge generated flows from one main surface 20c of the substrate 2 to the ground via conductor 21, reaches the lower main surface of the substrate 2, and is discharged to the outside.

In the conventional configuration in which the grounding via conductor 21 is not provided, the electric charge emitted from the person is signal-wired from a connector that electrically connects the light emitting element or the light receiving element and the measurement sensor package 1, for example, a bonding wire. It enters the conductor and causes noise.

In the present embodiment, the grounded via conductor 21 forms a path in the measurement sensor package 1 in which the electric charge released from the person easily flows, so that the electric charge is guided to this path and the electric charge is released to the outside, and the signal is released. Prevents entry into the wiring conductor.

In the present embodiment, the ground via conductor 21 is arranged along the outer shape of the substrate 2. Since the substrate 2 has a rectangular outer shape, the ground via conductor 21 is also arranged along the rectangular shape. That is, each grounding via conductor 21 is arranged so that the distance from each side forming the outline of the substrate 2 to the grounding via conductor 21 is the same. In the plan view of FIG. 1, the arrangement position of the grounding via conductor 21 is indicated by a broken line circle. For example, the three grounding via conductors 21 shown in the cross-sectional view of FIG. 2 are three grounding via conductors 21 arranged laterally at equal intervals on the upper side of the drawing in FIG. 1, and are the centers of the grounding via conductors 21. The virtual straight line connecting the two is arranged so as to be parallel to the long side of the substrate 2. The same applies to the other grounded via conductors 21. For example, in FIG. 1, two grounded via conductors 21 arranged vertically on the left side of the drawing have a virtual straight line connecting the centers parallel to the short side of the base 2. The two grounding via conductors 21 arranged in the horizontal direction on the lower side in the drawing are arranged so that the virtual straight line connecting the centers is parallel to the long side of the base 2.

In the present embodiment, a total of five grounding via conductors 21 surround the first accommodating recess 20a and the second accommodating recess 20b outside the first accommodating recess 20a and the second accommodating recess 20b, and the substrate 2 It is arranged along a rectangle which is the outer shape of. The grounding via conductor 21 is arranged in each of the three corners of the four corners of the rectangle, and is not arranged in the remaining one corner.

The arrangement position of the grounding via conductor 21 is preferably determined based on the distance from the first accommodating recess 20a and the distance from the second accommodating recess 20b. As described above, since unnecessary charge that causes noise flows through the ground via conductor 21 if it enters the signal wiring conductor, the signal wiring formed on the ground via conductor 21 and the measurement sensor package 1 The distance to the conductor 23 (including the inside of the substrate 2 and the bonding wire) is made larger than a predetermined distance to reduce the entry of unnecessary charge from the ground via conductor 21 into the signal wiring conductor 23.

In the present embodiment, of the four corners of the rectangle, the ground via is located at a position where the distance from the first accommodating recess 20a or the second accommodating recess 20b, that is, the distance from the signal wiring conductor 23 is smaller than the predetermined distance. It is preferable not to provide the conductor 21. In the present embodiment, the grounding via conductor 21 is not provided at one corner because the distance between the corner and the signal wiring conductor 23 is smaller than a predetermined distance.

The grounding via conductor 21 preferably has a low electrical resistance in order to induce unnecessary charges to be released to the outside of the package as described above, and in order to reduce the electrical resistance, the diameter may be made larger. preferable. However, if the diameter is made too large, the distance from the signal wiring conductor becomes small, and an unnecessary charge may enter the signal wiring conductor from the ground via conductor 21. Therefore, in consideration of these, for example, the size of the grounding via conductor 21 may be such that the diameter D is 10 μm to 500 μm.

The annular ground conductor layer 22 is a conductor layer provided on one main surface 20c of the substrate 2 in an annular shape so as to surround the opening of the first accommodating recess 20a and the opening of the second accommodating recess 20b. The annular conductor layer electrically connects each one end surface 21a of the ground via conductor 21 exposed on one main surface 20c of the substrate 2. The annular ground conductor layer 22 is a metal molten material-based bonding material such as solder, Au-Sn, or brazing material, or an epoxy-based, silicon-based, or thermoplastic material to bond the lid 3 to the substrate 2. It is bonded by a resin-based bonding material such as a resin, an anisotropic conductive resin, a conductive epoxy resin, or a conductive silicon resin.

The plurality of ground via conductors 21 are arranged along a rectangle that is the outer shape of the base 2, and one end surface 21a of each is also exposed to one main surface 20c of the base 2 along the rectangle that is the outer shape of the base 2. ing. In the present embodiment, as shown in FIG. 1, the annular ground conductor layer 22 for electrically connecting each one end surface 21a is also provided in a rectangular shape according to their arrangement positions. The annular ground conductor layer 22 includes a land portion 22a that connects to one end surface 21a of the ground via conductor 21, and a connection line portion 22b that connects each land portion. The land portion 22a is formed larger than the one end surface 21a in order to connect to the one end surface 21a of the grounding via conductor 21 reliably and with low resistance. For example, the land portion 22a has a width or diameter of 1 × D to 3 × D (1 to 3 times the diameter) with respect to the diameter D of one end surface 21a of the grounding via conductor 21. The connecting line portion 22b is thinner than the land portion 22a and is formed to have a constant line width.

The signal wiring conductor 23 is electrically connected to the light emitting element or the light receiving element, an electric signal input to the light emitting element is transmitted, and an electric signal output from the light receiving element is transmitted. The signal wiring conductor 23 in the present embodiment includes a bonding wire that is a connecting member connected to a light emitting element or a light receiving element, a first connection pad 23a and a second connection pad 23b to which the bonding wire is connected, and a first connection pad 23a. The signal via conductor 23c is electrically connected to the second connection pad 23b and extends linearly from directly below the connection pad to the other main surface of the substrate 2, and is composed of an external connection terminal 24. The external connection terminal 24 is electrically connected to the connection terminal of the external mounting board on which the measurement sensor including the measurement sensor package 1 is mounted by a bonding material such as solder.

The annular ground conductor layer 22 and the external connection terminal 24 have, for example, a nickel layer having a thickness of 0.5 to 10 μm and a thickness of 0 in order to improve the wettability with a bonding material such as solder and improve the corrosion resistance. . A gold layer of 5 to 5 μm may be sequentially adhered by a plating method.

If the substrate 2 can accommodate a light emitting element and a light receiving element and includes a ground via conductor 21, a signal wiring conductor 23, and the like, the dielectric layer of the substrate 2 is made of a ceramic insulating material, and the ground via conductor 21 and the ground via conductor 21 The signal wiring conductor 23 or the like may be a ceramic wiring substrate made of a conductor material, or the dielectric layer may be an organic wiring substrate made of a resin insulating material.

When the substrate 2 is a ceramic wiring board, each conductor is formed in a dielectric layer made of a ceramic material. The ceramic wiring board is formed from a plurality of ceramic dielectric layers.

Examples of the ceramic material used in the ceramic wiring substrate include aluminum oxide sintered body, mulite sintered body, silicon carbide sintered body, aluminum nitride sintered body, silicon nitride sintered body, and glass ceramics fired. Bounds and the like can be mentioned.

When the substrate 2 is an organic wiring board, a wiring conductor is formed in an insulating layer made of an organic material. The organic wiring board is formed from a plurality of organic dielectric layers.

The organic wiring board may be, for example, a printed wiring board, a build-up wiring board, a flexible wiring board, or the like, as long as the dielectric layer is made of an organic material. Examples of the organic material used in the organic wiring substrate include epoxy resin, polyimide resin, polyester resin, acrylic resin, phenol resin, fluororesin and the like.

Next, other embodiments of the present invention will be described. FIG. 4 is a cross-sectional view of the measurement sensor package 1A corresponding to the cross-sectional view shown in FIG. 2, and FIG. 5 is a cross-sectional view of the measurement sensor package 1A corresponding to the cross-sectional view shown in FIG.

The measurement sensor package 1A of the present embodiment is different from the measurement sensor package 1 of the above embodiment in that the base 2 further has an internal grounding conductor layer 25, and the other components have the same configuration. Therefore, the same reference code as that of the measurement sensor package 1 is attached to the same configuration, and detailed description thereof will be omitted.

The internal grounding conductor layer 25 is connected to the grounding potential and is disposed between the bottom of the second accommodating recess 20b and the other main surface of the substrate 2. The internal grounding conductor layer 25 is electrically connected to the grounding via conductor 21 inside the base 2, and a grounding potential is applied.

In a measurement sensor used for measuring blood flow, etc., the amount of light received by the light receiving element is relatively small, so the electric signal output from the light receiving element is weak, and noise is compared to the light emission control electric signal input to the light emitting element. Is greatly affected by.

The measurement sensor is mounted and used on an external mounting board, and electromagnetic waves caused by signals or the like flowing through the wiring of the external mounting board enter the measurement sensor package 1 from the other main surface side of the base 2. Therefore, noise may be mixed in the signal flowing through the signal wiring conductor 23.

As described above, the light receiving element side is particularly affected by noise. Therefore, in order to suppress the influence of noise from the external mounting substrate, the bottom and the other main surface of the second accommodating recess 20b in which the light receiving element is accommodated. By providing the internal grounding conductor layer 25 between the two, the internal grounding conductor layer 25 is located between the second accommodating recess 20b and the external mounting substrate, and functions as an electromagnetic shield.

By having the internal grounding conductor layer 25, the measurement sensor package 1A of the present embodiment can suppress the influence of noise and further improve the measurement accuracy.

The manufacturing method of the measurement sensor package 1 will be described. First, the substrate 2 is manufactured in the same manner as a known method for manufacturing a multilayer wiring board. When the substrate 2 is a ceramic wiring substrate and the ceramic material is alumina, it is first _{suitable for raw material powders such as alumina (Al 2} O ₃ ), silica (SiO ₂ ), calcia (CaO), and magnesia (MgO). An organic solvent and a solvent are added and mixed to form a slurry, which is molded into a sheet by a well-known doctor blade method, calendar roll method, or the like to obtain a ceramic green sheet (hereinafter, also referred to as a green sheet). After that, the green sheet is punched into a predetermined shape, and an organic solvent and a solvent are added and mixed with tungsten (W) and raw material powder such as a glass material to form a metal paste, which is then printed on the surface of the green sheet by a printing method such as screen printing. Print the pattern with. Further, for the via conductor, a through hole is provided in the green sheet, and the through hole is filled with the metal paste by screen printing or the like. A plurality of green sheets thus obtained are laminated and simultaneously fired at a temperature of about 1600 ° C. to produce a substrate 2.

On the other hand, a lid 3 obtained by cutting a glass material into a predetermined shape by cutting, cutting or the like is prepared, and a ground conductor layer 4 made of a metal thin film is formed on the main surface by vapor deposition, sputtering, baking or the like. At this time, the first opening 4a and the second opening 4b can be formed by patterning the metal thin film by a photolithography (wet etching) method, a dry etching method, or the like.

Next, the measurement sensor 100, which is another embodiment of the present invention, will be described. FIG. 6 is a cross-sectional view showing the configuration of the measurement sensor 100. The measurement sensor 100 includes the above-mentioned measurement sensor packages 1, 1A, a light emitting element 30 housed in the first housing recess 20a, and a light receiving element 31 housed in the second housing recess 20b. The light emitting element 30 is mounted on the first bottom surface 20d of the first accommodating recess 20a, and the light receiving element 31 is mounted on the second bottom surface 20e of the second accommodating recess 20b. The measurement sensor 100 is obtained by connecting the light emitting element 30 and the first connection pad 23a with a bonding wire 32, connecting the light receiving element 31 and the second connection pad 23b, and then joining the lid 3 to the substrate 2. Be done.

As the light emitting element 30, a semiconductor laser element such as VCSEL can be used, and as the light receiving element 31, various photodiodes such as a silicon photodiode, a GaAs photodiode, an InGaAs photodiode, and a germanium photodiode can be used. The light emitting element 30 and the light receiving element 31 may be appropriately selected depending on the type of the object to be measured, the type of the parameter to be measured, and the like.

When measuring the blood flow, for example, in order to measure by utilizing the Doppler effect of light, the VCSEL which is the light emitting element 30 may be capable of emitting laser light having a wavelength of 780 nm. When performing other measurements, a light emitting element 30 that emits a laser beam having a wavelength corresponding to the measurement purpose may be selected. The light receiving element 31 may be capable of receiving the emitted light of the light emitting element 30 when the received light does not change in wavelength from the laser light emitted from the light emitting element 30, and when there is a change in wavelength, after the change. Anything that can receive light of the wavelength of

In the present embodiment, for example, the light emitting element 30 and the first connection pad 23a are electrically connected by the bonding wire 32, and the light receiving element 31 and the second connection pad 23b are electrically connected, but the flip chip. Other connection methods such as connection, bump connection, and connection using an anisotropic conductive film may be used.

The measurement sensor 100 is mounted on an external mounting board and used. On the external mounting substrate, for example, a control element that controls the light emission of the light emitting element 30, an arithmetic element that calculates the blood flow velocity and the like from the output signal of the light receiving element 31, and the like are also mounted.

In the case of measurement, the light emitting element control current is input to the measurement sensor 100 from the external mounting substrate via the external connection terminal 24 with the fingertips of the fingers in contact with the surface of the lid 3 as the object to be measured, and a signal is obtained. It is input to the light emitting element 30 through the via conductor 23c and the second connection pad 23b, and the light for measurement is emitted from the light emitting element 30. When the emitted light passes through the first opening 4a, passes through the lid 3 and is irradiated to the fingertip, it is scattered by blood cell cells in the blood. When the scattered light that has passed through the lid 3 and passed through the second opening 4b is received by the light receiving element 31, an electric signal corresponding to the amount of light received is output from the light receiving element 31. The output signal passes through the first connection pad 23a and the signal via conductor 23c, and is output from the measurement sensor 100 to the external mounting board via the external connection terminal 24.

In the external mounting board, the signal output from the measurement sensor 100 is input to the arithmetic element, and for example, the frequency of the irradiation light which is the light emitted from the light emitting element 30 and the scattered light which is the light received by the light receiving element 31. The blood flow velocity can be calculated based on the frequency of.

In the above, the grounding via conductor 21 is formed in a straight line in the vertical direction in the base 2, but is electrically connected from one main surface 20c of the base 2 to the external connection terminal 24 on the other main surface. If it is, it may not be in a straight line, but may be formed in the substrate 2 by being displaced by the inner layer wiring, the internal grounding conductor layer 25, or the like.

Further, in the present embodiment, the annular ground conductor layer 22 is not an essential configuration, but is configured so that the ground conductor layer 4 formed on the lid 3 and the ground via conductor 21 are directly joined and electrically connected. You may.

Further, the internal grounding conductor layer 25 extends further in the surface direction from between the bottom portion of the second accommodating recess 20b and the other main surface of the substrate 2, and is between the bottom portion of the first accommodating recess 20a and the other main surface. It may be arranged.

As an example, in the measurement sensor package 1 shown in FIGS. 1 to 3, the amount of crosstalk between the first connection pad 23a and the second connection pad 23b was calculated by simulation. In this simulation, the configurations other than the base 2, the first connection pad 23a, and the second connection pad 23b are omitted, and the base 2 is a perfect conductor. The shape of the first connection pad 23a has a vertical length of 1.0 mm and a horizontal length of 0.5 mm. The shape of the second connection pad 23b has a vertical length of 1.0 mm and a horizontal length of 0.5 mm. Further, in a plan view, the distance between the center of the first connection pad 23a and the center of the second connection pad 23b was set to 3.0 mm. Further, the depth of the first accommodating recess 20a is set to 1.0 mm, the depth of the second accommodating recess 20b is set to 2.0 mm, and the first stepped surface 20f and the substrate 2 are set in the thickness direction of the substrate 2. The distance between the one main surface 20c was set to 0.25 mm, and the distance between the second stepped surface 20g and the one main surface 20c of the substrate 2 was set to 0.75 mm.

Under the above conditions, the frequency dependence of the amount of crosstalk between the first connection pad 23a and the second connection pad 23b was calculated. The specific calculation method is as follows. A voltage signal output from the second connection pad 23b when a voltage signal is input to the first connection pad 23a is calculated, and a predetermined coefficient is obtained as a logarithm of the ratio of the strength of the output voltage signal to the strength of the input voltage signal. Was multiplied to obtain the amount of crosstalk. Further, the frequency dependence of the amount of crosstalk was calculated by changing the frequency of the input voltage in the range of 1 kHz to 20 kHz. In this simulation, the larger the absolute value of the crosstalk amount, the better the electrical shielding between the first connection pad 23a and the second connection pad 23b, and the more between the first connection pad 23a and the second connection pad 23b. It can be judged that the electrical crosstalk of the is suppressed.

As a comparative example, the depth of the first accommodating recess 20a is equal to the depth of the second accommodating recess 20b, and the distance between the first stepped surface 20f and one main surface 20c of the substrate 2 in the thickness direction of the substrate 2 In the same measurement sensor package as in the measurement sensor package of the embodiment, the same as in the simulation of the embodiment, except that the distance between the second stepped surface 20g and the one main surface 20c of the substrate 2 is equal. , The frequency dependence of the amount of crosstalk between the first connection pad 23a and the second connection pad 23b was calculated. In the comparative example, the depth of the first accommodating recess 20a and the depth of the second accommodating recess 20b are set to 0.5 mm, and one main surface of the first stepped surface 20f and the substrate 2 is set in the thickness direction of the substrate 2. The distance between the first stepped surface 20g and the one main surface 20c of the substrate 2 was set to 0.25 mm.

FIG. 7 shows the results of Examples and Comparative Examples. FIG. 7 (a) shows the results of the comparative example, and FIG. 7 (b) shows the results of the examples. As shown in FIGS. 7 (a) and 7 (b), the results obtained that the amount of crosstalk does not depend on the frequency of the input voltage in both the examples and the comparative examples. This result shows that the amount of crosstalk in this simulation depends substantially only on the length of the electrical path between the first connection pad 23a and the second connection pad 23b formed inside the substrate 2. It is considered that the length of this electric path is substantially the same for the electric signals in the frequency band of 1 kHz to 20 kHz. Further, from FIGS. 7 (a) and 7 (b), it can be seen that the amount of crosstalk in the examples is smaller than the amount of crosstalk in the comparative examples in the entire frequency band of 1 kHz to 20 kHz.

FIG. 8 is a diagram showing the evaluation results of Examples and Comparative Examples. As an evaluation result, the average amount of crosstalk was used. The average amount of crosstalk is the average value of the amount of crosstalk over the frequency band of 1 kHz to 20 kHz. It can be evaluated that the smaller the absolute value of the average crosstalk amount is, the more remarkable the electrical crosstalk is, and the larger the absolute value of the average crosstalk amount is, the more the electrical crosstalk is suppressed. As shown in FIG. 8, it can be evaluated that the electrical crosstalk is suppressed in the examples as compared with the comparative examples.

As described above, in the embodiment, the depth of the first accommodating recess 20a is made shallower than the depth of the second accommodating recess 20b, so that the electrical between the first connecting pad 23a and the second accommodating pad 23b is electrical. It was found that crosstalk was suppressed.

1 Package for measurement sensor 1A Package for measurement sensor 2 Base 3 Cover 4 Ground conductor layer
4a 1st opening 4b 2nd opening 20a 1st accommodating recess 20b 2nd accommodating recess 20c One main surface 20d 1st bottom surface 20e 2nd bottom surface 20f 1st step surface 20g 2nd step surface 20h 1st step portion 20i 2nd step portion 21 Grounding Via Conductor 21a One End Face 21b Another End Face 22 Circular Ground Conductor Layer 22a Land Part 22b Connection Line Part 23 Signal Wiring Conductor 23a First Connection Pad 23b Second Connection Pad 23c Signal Via Conductor 24 External Connection Terminal 25 Internal Ground Conductor Layer 30 Light emitting element 31 Light receiving element 32 Bonding wire 100 Measurement sensor

Claims (5)

A first main surface, a second main surface, a first accommodating recess located on the first main surface including a first bottom surface on which a light emitting element is mounted, and a light receiving element located on the first main surface. Is arranged between a second accommodating recess including a second bottom surface on which the is mounted, the first accommodating recess and the second main surface, and / or between the second accommodating recess and the second main surface. A substrate having an internal grounding conductor layer,
It is provided with a lid that covers the first accommodating recess and the second accommodating recess, transmits the light emitted from the light emitting element, and transmits the light received by the light receiving element.
The first opening through which the light emitted from the light emitting element passes and the light received by the light receiving element pass through the first accommodating recess and the main surface of the lid on the side facing the second accommodating recess. A second opening is provided, and a ground conductor layer electrically connected to the internal ground conductor layer is located .
The width of the second opening is smaller than the opening width of the second accommodating recess when viewed in a cross section orthogonal to the first main surface and passing through the first accommodating recess and the second accommodating recess. Package for measurement sensor. A first main surface, a second main surface, a first accommodating recess located on the first main surface including a first bottom surface on which a light emitting element is mounted, and a light receiving element located on the first main surface. There comprises a substrate having a second accommodation recess including a second bottom surface to be mounted, and a internal grounding conductor layer disposed between the front Stories second accommodation recess and the second main surface,
The inner surface of the front Stories second housing recess, the step portion having a step surface extending in the plane direction of the first main surface is provided, the connection pad the upper step surface, which is pre-Symbol electrically connected to the light receiving element Is arranged, and inside the substrate, a signal via conductor connected to the connection pad and extending to the second main surface is arranged.
The measurement characterized in that the internal grounding conductor layer extends from a position overlapping the second bottom surface of the second accommodating recess to the outside of the second accommodating recess beyond the signal via conductor in a plan view. Sensor package. The substrate further has a grounding via conductor located outside the first accommodating recess and the second accommodating recess and penetrating in the thickness direction of the substrate.
The package for a measurement sensor according to claim 1 or 2, wherein the internal grounding conductor layer is electrically connected to the grounding via conductor. The package for a measurement sensor according to claim 2, wherein the internal ground conductor layer is positioned so as to overlap the connection pad in a plan view. The measurement sensor package according to any one of claims 1 to 4.
The light emitting element accommodated in the first accommodating recess and
A measurement sensor including a light receiving element accommodated in the second accommodating recess.

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