JP2009162695A - Mounting structure of air flow detection chip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mounting structure of an air flow detection chip that suppresses application of stress to an air flow detecting section of the air flow detection chip, accurately detects air flow, secures high reliability, is easily manufactured and managed, and reduces the manufacturing cost. <P>SOLUTION: In this air flow detection chip 20, the air flow detecting section 20b is formed at one end on the main surface side of a semiconductor chip 20a, and a pad section 20c for wire bonding is formed on the other end. A sheet-like member 70 that has an area larger than that of the air flow detection chip 20 and has an adhesive layer 70a partially in a region under the pad section 20c other than the air flow detecting section 20b is interposed between the air flow detection chip 20 and a substrate member 80. In this mounting structure, the air flow detection chip 20 is mounted on the sheet-like member 70, and is joined to the substrate member 80 through an adhesive layer 70a of the sheet-like member 70. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a structure for mounting an air flow rate detection chip on a substrate member.

  A mounting structure of an air flow rate detection chip on a substrate member is disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-12987 (Patent Document 1).

  FIG. 9A is a cross-sectional view showing the thermal air flow sensor 1 disclosed in Patent Document 1. FIG. FIG. 9B is an enlarged view around the semiconductor sensor element 2 in FIG.

  As shown in FIG. 9A, the thermal air flow sensor 1 includes a semiconductor sensor element 2 which is an air flow detection chip, laminated substrates 8a, 8b and 8c as substrate members for supporting the semiconductor sensor element 2, and a semiconductor. It includes a cover 9 that covers the sensor element 2 and forms an air flow path space S.

  At one end of the semiconductor sensor element 2, as shown in FIG. 9B, a cavity 5k formed by anisotropic etching from the lower surface and a diaphragm 5d as a membrane (thin portion) are formed on the diaphragm 5d. An air flow rate detection unit configured to include the generated heating resistor 3 and the temperature measuring resistor 4 for measuring the air temperature is formed. The semiconductor sensor element 2 is bonded to the depressions of the laminated substrates 8a, 8b, and 8c by a sensor adhesive 7 applied to the lower surface of the electrode 6 that is a pad portion.

In the thermal air flow sensor 1 shown in FIG. 9A, the laminated substrates 8a, 8b, and 8c are not only substrate members for mounting the semiconductor sensor element 2, but also a circuit board that forms a control circuit for the semiconductor sensor element 2. Doubles as The cover 9 that covers the semiconductor sensor element 2 has a partition wall 9s that partitions the air flow path space S and the circuit space K on the multilayer substrate 8a. The circuit space K is filled with a sealing material 10 made of gel, and portions of the laminated substrates 8a, 8b, and 8c belonging to the circuit space K are embedded in the sealing material 10.
Japanese Patent Laid-Open No. 2001-12987

  In the semiconductor type air flow rate detection device (air flow meter), a structure made of a membrane is formed on the air flow rate detection chip, like the thermal air flow rate sensor 1 shown in FIG. For this reason, the strength around the membrane is very weak, and it can be said that the membrane is brittle against external stress. In addition, the stress changes the resistance value of the heating resistor 3 and the resistance temperature detector 4 around the membrane shown in FIG. 9B, and the sensor characteristics change, which is fatal for a sensor that requires high accuracy. Flaws. For this reason, it is important that the air flow rate detection chip has a mounting structure that is not easily stressed.

  With respect to the above-described problem, the thermal air flow sensor 1 is liquid only on the lower surface of the electrode 6 at the other end opposite to the air flow rate detection part of the semiconductor sensor element 2 as shown in FIG. The semiconductor sensor element 2 is cantilevered and fixed so that no stress is applied to the air flow rate detection portion of the semiconductor sensor element 2. However, in the mounting structure of the semiconductor sensor element 2 shown in FIG. 9B, the sensor adhesive 7 does not flow into the lower part of the membrane during application and the sensor adhesive 7 does not creep up on the surface of the semiconductor sensor element 2. Therefore, it is necessary to strictly manage the application amount of the sensor adhesive 7, the curing temperature, and the like. This complicates the management of the sensor adhesive 7 and increases the manufacturing cost. In addition, even after manufacture, the sensor adhesive 7 may flow into the lower part of the membrane or creep up to the surface of the semiconductor sensor element 2 due to changes over time.

  Therefore, the present invention is a structure for mounting an air flow rate detection chip on a substrate member, and it is difficult for stress to be applied to the air flow rate detection part of the air flow rate detection chip, and highly accurate air flow rate detection is possible and high reliability is ensured. Another object of the present invention is to provide an air flow rate detection chip mounting structure that can be manufactured easily and can be manufactured at low cost.

  The invention according to claim 1 is a mounting structure of an air flow rate detection chip on a substrate member, wherein the air flow rate detection chip is formed with an air flow rate detection unit at one end on the main surface side of the semiconductor chip. Is an air flow rate detection chip in which a pad portion for wire bonding is formed at the other end, and the area between the air flow rate detection chip and the substrate member is larger than the air flow rate detection chip, A sheet-like member in which an adhesive layer is partially formed is interposed in a region below the pad portion excluding the air flow rate detection unit, and the air flow rate detection chip is placed on the sheet-like member. The sheet-like member is bonded to the substrate member with an adhesive layer.

  In the mounting structure of the air flow rate detection chip, the air flow rate detection chip is joined to the substrate member with an adhesive layer partially formed on the sheet-like member. The adhesive layer of the sheet-like member is partially formed in a region below the pad portion excluding the air flow rate detection portion of the air flow rate detection chip. Therefore, the air flow rate detection chip bonded onto the substrate member via the sheet-like member has a cantilever structure in which one end of the pad portion of the semiconductor chip is fixed. For this reason, the mounting structure is similar to a conventional cantilever structure using an adhesive, and basically has a structure in which external air stress is not easily applied to the air flow rate detection unit.

  On the other hand, in the mounting structure of the air flow rate detection chip, the sheet-like member has a larger area than the air flow rate detection chip, and the air flow rate detection chip is placed on the sheet-like member, and the adhesive layer Is bonded onto the substrate member. Therefore, unlike the conventional cantilever structure using an adhesive, the mounting structure includes a part of the sheet-like member that does not contribute to the bonding also below the air flow rate detection portion of the air flow rate detection chip. For this reason, the mounting structure described above can suppress the vibration with respect to the vibration of one end of the air flow rate detection unit that is not fixed, as compared with a conventional cantilever structure using an adhesive. Also, the external stress applied to the air flow rate detection unit can be suppressed. Therefore, in the mounting structure described above, the air flow rate can be detected with higher accuracy and higher reliability can be ensured as compared with the cantilever structure using the conventional adhesive.

  In the mounting structure of the air flow rate detection chip, the adhesive layer can be accurately patterned in advance on the sheet-like member, so that the application amount and curing temperature are the same as in the case of using a conventional liquid adhesive. There is no need to strictly manage etc. For this reason, the mounting structure described above is easier to manage and can reduce the manufacturing cost compared to a conventional mounting structure using a liquid adhesive.

  As described above, the mounting structure of the air flow rate detection chip is a mounting structure of the air flow rate detection chip on the board member, and the air flow rate detection part of the air flow rate detection chip is hardly subjected to stress, and is highly accurate. The air flow rate can be detected and high reliability can be ensured, and the mounting structure of the air flow rate detection chip that can easily manufacture and reduce the manufacturing cost can be obtained.

  The sheet-like member in the mounting structure is preferably a tape-like sheet-like member in which the adhesive layer is formed on a base film as described in claim 2, for example.

  According to this, the pattern formation of the adhesive layer can be performed accurately and easily. In addition, the thickness of the sheet-like member can be made substantially uniform between the portion with and without the adhesive layer by forming the adhesive layer thin. For this reason, when the sheet-like member is interposed, the gap between the sheet-like member and the substrate member or the air flow rate detection chip can be reduced as much as possible, and the parallelism between the substrate member and the air flow rate detection chip can be easily ensured. become.

  In this case, it is preferable that the adhesive layer is made of an ultraviolet peelable adhesive, for example, as described in claim 3.

  The ultraviolet peelable adhesive has a function of losing the adhesive force when irradiated with ultraviolet rays. Therefore, by using a UV-peelable adhesive, it is possible to remove the adhesive strength of the portion irradiated with ultraviolet rays by simple masking and pattern the portion not irradiated with ultraviolet rays as the adhesive layer. is there. In this case, a layer made of an ultraviolet peeling adhesive is formed on the entire surface of the base film, and a portion not irradiated with ultraviolet rays is defined as the adhesive layer. For this reason, the thickness of a sheet-like member can be made uniform over the whole area.

  On the other hand, without using a base film, as described in claim 4, the entire sheet-like member is made of an ultraviolet peelable adhesive, and the adhesive layer is irradiated with ultraviolet rays of the ultraviolet peelable adhesive. The remaining portion of the sheet-like member excluding the adhesive layer may be a portion irradiated with ultraviolet rays of the ultraviolet peelable adhesive. According to this, a thick adhesive layer can be secured in a state where the thickness of the sheet-like member is uniform over the entire area.

  In this case, as described in claim 5, it is preferable that beads of the same size are contained in the ultraviolet peelable adhesive of the sheet-like member. According to this, ensuring of uniform thickness over the whole area of an above-described sheet-like member becomes easy.

  In the mounting structure of the air flow rate detection chip described above, the air flow rate detection chip has a groove formed on the back surface side of the semiconductor chip, and a membrane is formed on the main surface side by the groove. This is suitable for an air flow rate detection chip in which the air flow rate detection unit is arranged around the membrane.

  An air flow rate detection chip in which a groove is formed on the back surface side of the semiconductor chip, a membrane is formed on the main surface side by the groove, and an air flow rate detection unit is arranged around the membrane has high sensitivity. The strength around is very weak, and the structure is brittle against external stress. Further, due to the stress, a characteristic change is likely to occur due to a change in the resistance value of the heating resistor or the resistance temperature detector of the air flow rate detector disposed around the membrane. Even with a semiconductor chip having such a membrane structure, according to the mounting structure described above, the stress applied to the air flow rate detection part of the air flow rate detection chip can be reduced as much as possible. An air flow rate detection device can be configured.

  For the same reason, the mounting structure of the air flow rate detection chip described above is such that the air flow rate detection chip is formed with a groove from the main surface side of the semiconductor chip, and the groove is formed on the main surface side. It is also suitable for an air flow rate detection chip in which a membrane is formed on the membrane and the air flow rate detection unit is arranged around the membrane.

  In order to measure the air flow rate with high accuracy in the air flow rate detection device, the air flow rate detection device must not have a structure that generates turbulent flow on the air flow rate detection chip. Therefore, as described in claim 8, in the mounting structure of the air flow rate detection chip, the surface on the main surface side of the air flow rate detection chip and the surface of the substrate member surrounding the air flow rate detection chip are: It is preferable that they are set to the same height.

  As described above, in the mounting structure, it is easy to ensure the parallelism between the board member and the air flow rate detection chip. Further, in the above mounting structure, the sheet-like member can be easily deformed by applying pressure from above the air flow rate detection chip and crushing the sheet-like member. Therefore, in the above mounting structure, the surface of the air flow rate detection chip and the surface of the substrate member surrounding the air flow rate detection chip can be easily flattened at the same height, and turbulence is generated on the air flow rate detection chip. It is difficult to form a highly accurate air flow rate detection device.

  Further, according to the mounting structure of the air flow rate detection chip described above, as described in claim 9, a cover that covers the air flow rate detection chip is provided on the air flow rate detection chip or the substrate member. A partition wall that divides the air flow path space to which the circuit board is connected and the circuit space in which the circuit board connected to the pad portion is disposed, the circuit space is filled with a sealing material, and the circuit board is sealed with the seal. It is suitable when it is embedded in a material.

  Usually, gel is used as the sealing material for the circuit space, and serves to protect the circuit board on which the control circuit for the air flow rate detection chip and the like are formed. The sealing material made of the gel exudes from the gap between the partition wall and the air flow rate detection chip or the substrate member even though it is separated from the air flow path space by the partition wall of the cover to detect the air flow rate. The air may flow into the air flow path space to which the part belongs. Even when the sealing material made of gel flows into the air flow path space in this way, as described above, in the mounting structure, the sheet-like member is also interposed below the air flow rate detection unit. The wraparound of the gel below the detection unit can be prevented. Therefore, also in this case, it is possible to detect the air flow rate with high accuracy and to provide a highly reliable mounting structure.

  As described above, the mounting structure of the air flow rate detection chip is a mounting structure of the air flow rate detection chip on the board member, and the air flow rate detection part of the air flow rate detection chip is hardly subjected to stress, and is highly accurate. The air flow rate can be detected and high reliability can be ensured, and the mounting structure of the air flow rate detection chip that can easily manufacture and reduce the manufacturing cost can be obtained.

  Therefore, as described in claim 10, the mounting structure of the air flow rate detection chip described above is used for an in-vehicle air flow rate detection device that is required to be highly accurate, highly reliable and inexpensive. It is preferable.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is an example of a mounting structure of an air flow rate detection chip according to the present invention, and is a schematic cross-sectional view showing a main part of an air flow rate measuring device (air flow meter) 100.

  In the air flow rate measuring device 100 of FIG. 1, the air flow rate detection chip 20 is mounted on a substrate member 80 on which a lead frame 80a is molded. In the air flow rate detection chip 20, an air flow rate detection unit 20b is formed at one end portion on the main surface side of the semiconductor chip 20a, and a pad portion 20c for wire bonding is formed at the other end portion.

  More specifically, the air flow rate detection chip 20 mounted on the air flow rate measuring device 100 of FIG. 1 has a groove 20d formed on the back surface side of the semiconductor chip 20a, and the membrane 20e is formed on the main surface side by the groove 20d. An air flow rate detector 20b is formed around the membrane 20e. The air flow rate detection chip 20 has a high sensitivity, but has a very weak strength around the membrane 20e and is brittle against external stress. In addition, due to the stress, characteristic variation is likely to occur due to a change in the resistance value of the heating resistor or the resistance temperature detector of the air flow rate detection unit 20b disposed around the membrane 20e. In order to cover the weak points of the semiconductor chip 20a having such a membrane structure, the following mounting structure is used in the air flow rate measuring device 100 of FIG.

  That is, in the air flow rate measuring device 100 in FIG. 1, the area between the air flow rate detection chip 20 and the substrate member 80 is larger in area than the air flow rate detection chip 20 and below the pad portion 20 c except for the air flow rate detection unit 20 b. A sheet-like member 70 in which an adhesive layer 70a is partially formed is interposed.

  If it demonstrates in detail, the sheet-like member 70 of FIG. 1 is a tape-like sheet-like member in which the adhesive layer 70a is formed on both surfaces of the base film 70c. The adhesive layer 70a is made of an ultraviolet peelable adhesive having a function of losing the adhesive force when irradiated with ultraviolet rays. Examples of the sheet-like member on which the ultraviolet peelable adhesive is formed on the entire surface of the base film include a dicing die bond film used in semiconductor wafer processing. By using the ultraviolet peelable adhesive, as will be described later, a layer made of the ultraviolet peelable adhesive is formed on the entire surface of the base film 70c, and the adhesive strength of the portion irradiated with ultraviolet rays is eliminated by simple masking, It is possible to pattern-form the part not irradiated with ultraviolet rays as the adhesive layer 70a. In addition, the part shown with the code | symbol 70b in the sheet-like member 70 of FIG. 1 is the non-adhesion layer which lost the adhesive force by ultraviolet irradiation.

  The air flow rate detection chip 20 is placed on the sheet-like member 70 and joined to the substrate member 80 by the adhesive layer 70 a of the sheet-like member 70. In the mounting structure of the air flow rate detection chip 20 shown in FIG. 1, the air flow rate detection chip 20 is joined to the substrate member 80 with an adhesive layer 70 a partially formed on the sheet-like member 70. The adhesive layer 70 a of the sheet-like member 70 is partially formed in a region below the pad portion 20 c excluding the air flow rate detection portion 20 b of the air flow rate detection chip 20. Therefore, the air flow rate detection chip 20 joined onto the substrate member 80 via the sheet-like member 70 has a cantilever structure in which one end of the pad portion 20c of the semiconductor chip 20a is fixed. For this reason, the mounting structure is similar to the conventional cantilever structure using the adhesive 7 shown in FIG. 9 (b), and is basically structured such that external air stress is hardly applied to the air flow rate detector 20b. It has become.

  On the other hand, in the mounting structure of the air flow rate detection chip 20 shown in FIG. 1, the sheet-like member 70 has a larger area than the air flow rate detection chip 20, and the air flow rate detection chip 20 is placed on the sheet-like member 70. It is placed and bonded onto the substrate member 80 by the adhesive layer 70a. Therefore, unlike the conventional cantilever structure using the adhesive 7 shown in FIG. 9B, the mounting structure is a sheet that does not contribute to the bonding even below the air flow rate detection unit 20b of the air flow rate detection chip 20. A part of the shaped member is interposed. For this reason, the mounting structure is more resistant to vibration at one end of the unfixed air flow rate detection unit 20b than the conventional cantilever structure using the adhesive 7 shown in FIG. The vibration can be suppressed, and the stress from the outside applied to the air flow rate detection unit 20b can also be suppressed by this. Therefore, in the mounting structure described above, the air flow rate can be detected with higher accuracy and higher reliability can be ensured as compared with the conventional cantilever structure using the adhesive 7 shown in FIG. 9B. be able to.

  Further, in the mounting structure of the air flow rate detection chip 20 shown in FIG. 1, since the adhesive layer 70a can be accurately patterned in advance on the sheet-like member 70, the conventional liquid state shown in FIG. Unlike the case where the adhesive 7 is used, it is not necessary to strictly manage the coating amount, the curing temperature, and the like. For this reason, the mounting structure described above is easier to manage and can reduce the manufacturing cost compared to the conventional mounting structure using the liquid adhesive 7 shown in FIG.

  In particular, in the case of the tape-like sheet-like member 70 in which the adhesive layer 70a is formed on the base film 70c of FIG. 1, the pattern formation of the adhesive layer 70a can be performed accurately and easily. Further, the adhesive layer 70a can be formed thin, and the thickness of the sheet-like member 70 can be made substantially uniform between the portion with and without the adhesive layer 70a. For this reason, when the sheet-like member 70 is interposed, the gap between the sheet-like member 70 and the substrate member 80 and the air flow rate detection chip 20 can be reduced as much as possible, and the substrate member 80 and the air flow rate detection chip 20 can be reduced. It becomes easy to ensure parallelism. Further, when an ultraviolet peelable adhesive is used as the adhesive layer 70a, as described later, a layer made of an ultraviolet peelable adhesive is formed on the entire surface of the base film 70c, and the portion not irradiated with ultraviolet rays is bonded to the above-mentioned adhesive layer 70a. This is layer 70a. For this reason, the thickness of the sheet-like member 70 can be made uniform over the entire area. In the sheet-like member 70 shown in FIG. 1, the adhesive layer 70a made of an ultraviolet peeling adhesive is formed on both surfaces of the base film 70c. However, the present invention is not limited to this. For example, the adhesive layer 70a is formed only on one surface. The other surface may be a sheet-like member in which a layer made of a normal adhesive is formed on the entire surface.

  9A, the mounting structure of the air flow rate detection chip 20 shown in FIG. 1 is such that the cover 9 of FIG. The circuit shown in FIG. 9A is formed on the chip 20 or the substrate member 80 by arranging the circuit board 30 connected to the air flow path space S shown in FIG. 9A to which the air flow rate detector 20b belongs and the pad 20c. A partition wall 9 s for partitioning the space K is provided, which is suitable when the circuit space K is filled with the sealing material 10 and the circuit board 30 is embedded in the sealing material 10.

  Usually, gel is used for the sealing material 10 in the circuit space K, and the role of protecting the circuit board 30 and the electrical connection portions (bonding wires, pads, etc.) on which the control circuit of the air flow rate detection chip 20 is formed. Fulfill. Although the sealing material 10 made of the gel is separated from the air flow path space S by the partition wall 9 s of the cover 9, the sealing material 10 is formed from the gap between the partition wall 9 s and the air flow rate detection chip 20 or the substrate member 80. It may ooze out and flow into the air flow path space S to which the air flow rate detection unit 20b belongs. Thus, even when the sealing material 10 made of gel flows into the air flow path space S, as described above, in the mounting structure, the sheet-like member 70 is interposed below the air flow rate detection unit 20b to Since it is spread over the entire surface of the flow rate detection chip 20, it is possible to prevent the gel from wrapping around the air flow rate detection unit 20b. Therefore, also in this case, it is possible to detect the air flow rate with high accuracy and to provide a highly reliable mounting structure.

  As described above, the mounting structure of FIG. 1 is a mounting structure of the air flow rate detection chip 20 on the board member 80, and the air flow rate detection unit 20b of the air flow rate detection chip 20 is not easily stressed and is highly accurate. The air flow rate detection chip can be detected and high reliability can be secured, and the mounting structure of the air flow rate detection chip can be easily managed and the manufacturing cost can be reduced.

  FIGS. 2A and 2B are examples of different mounting structures, and are schematic cross-sectional views showing the main parts of the air flow rate measuring devices 101 and 102, respectively. In addition, in each air flow measuring device to which the air flow rate detecting chip mounting structure exemplified below is applied, the same reference numerals are given to the same parts as the air flow measuring device 100 in FIG.

  In the mounting structure of the air flow rate detection chip 20 used in the air flow rate measuring device 101 in FIG. 2A, the base film 70 c as shown in FIG. 1 is not used for the sheet-like member 71. The entire sheet-like member 71 is made of an ultraviolet peelable adhesive, the adhesive layer 71a is a portion of the ultraviolet peelable adhesive that is not irradiated with ultraviolet rays, and the remaining portion of the sheet-like member 71 excluding the adhesive layer 71a (Non-adhesive layer) 71b is a portion irradiated with ultraviolet rays of the ultraviolet peeling adhesive. The sheet-like member 71 in FIG. 2A can secure a thick adhesive layer 71a in a state where the thickness of the sheet-like member 71 is uniform over the entire area.

  In the mounting structure of the air flow rate detection chip 20 used in the air flow rate measuring device 102 in FIG. 2B, the entire sheet-like member 71 similar to the sheet-like member 71 in FIG. The member 72 contains beads 72c of the same size. The beads 72c are distributed over the entire adhesive layer 72a not irradiated with ultraviolet rays and the non-adhesive layer 72b irradiated with ultraviolet rays. In the sheet-like member 72 in FIG. 2B, it is easy to ensure a uniform thickness over the entire area, as compared with the sheet-like member 71 in FIG.

  FIG. 3 is a schematic cross-sectional view showing a main part of the air flow rate measuring device 103 as another example. In the following illustration of the mounting structure, the mounting structure using the sheet-like member 71 of FIG. 2A will be described for the sake of simplicity, but the sheet-like member 70 of FIG. 1 and FIG. The same applies to the sheet-like member 72.

  3 uses the same sheet-like member 71 as the air flow measurement device 101 in FIG. 2A. On the other hand, the mounted air flow rate detection chip 21 is different from the air flow rate detection chip 20 of FIG. 2A in that a groove 21d is formed from the main surface side of the semiconductor chip 21a by surface micromachining, and the groove 21d mainly A membrane 21e is formed on the surface side. An air flow rate detector 21b is disposed around the membrane 21e.

  A membrane 21e is also formed in the air flow rate detection chip 21 of FIG. 3, and an air flow rate detection unit 21b is disposed around the membrane 21e. Therefore, the air flow rate detection chip 21 of FIG. 3 is similar to the air flow rate detection chip 20 described above and has high sensitivity. On the other hand, the membrane structure in the air flow rate detection chip 21 in FIG. 3 is different from the membrane structure in the air flow rate detection chip 20 in FIG. 1, and a thick layer of the semiconductor chip 21a is left below the membrane 21e, and stress is concentrated. It has a difficult structure. For this reason, the air flow rate detection chip 21 of FIG. 3 is easier to handle and easier to handle in the assembly process than the air flow rate detection chip 20 of FIG. However, since the membrane 21e is also formed in the air flow rate detection chip 21 in FIG. 3, the strength around the membrane 21e is still weak and the structure must be weak against external stress, and the characteristic changes due to the stress. It is also a structure that tends to occur. Therefore, even with the air flow rate detection chip 21 of FIG. 3, according to the mounting structure described above, the stress applied to the air flow rate detection part 21b of the air flow rate detection chip 21 can be reduced as much as possible, and the sensitivity is high and the reliability is high. The air flow rate detection device 103 can be configured.

  FIG. 4 is a view showing a preferred mounting example of the air flow rate detection chip 20, and FIG. 4A is a schematic cross-sectional view showing the main part of the air flow rate measuring device 104. FIG. 4B is a diagram illustrating the mounting method of FIG.

  In order to measure the air flow rate with high accuracy in the air flow rate detection device, the air flow rate detection device must not have a structure that generates turbulent flow on the air flow rate detection chip. Therefore, as indicated by a one-dot chain line A in the air flow rate measuring device 104 of FIG. 4A, the surface Sa on the main surface side of the air flow rate detection chip 20 and the surface of the substrate member 80 surrounding the air flow rate detection chip 20 It is preferable that Sb is set at the same height.

  As described above, in the mounting structure, it is easy to ensure the parallelism between the substrate member 80 and the air flow rate detection chip 20. In the mounting structure, as shown in FIG. 4B, the sheet-like member 71 can be easily deformed by applying pressure from above the air flow rate detection chip 20 and crushing the sheet-like member 71. . As a result, as in the mounting structure of FIG. 4A, the surface Sa of the air flow rate detection chip 20 and the surface Sb of the substrate member 80 surrounding the air flow rate detection chip 20 can be easily flattened at the same height. In addition, it is possible to configure a highly accurate air flow rate detection device 104 that hardly generates turbulent flow on the air flow rate detection chip 20.

  Next, a method for forming the mounting structure will be described.

  FIGS. 5A to 5D are examples of the method for forming the mounting structure, and are cross-sectional views for each process of forming the mounting structure in the air flow measuring device 101 in FIG.

  First, as shown in FIG. 5A, a sheet-like member 73 made entirely of an adhesive layer 73 a made of an ultraviolet peelable adhesive is bonded to a predetermined position of the substrate member 80. Next, as shown in FIG. 5B, a predetermined portion of the sheet-like member 73 is masked with a mask M1, and the sheet-like member 73 is selectively irradiated with ultraviolet rays. As a result, as shown in FIG. 5 (c), the sheet-like member 73 of FIG. 5 (a) was irradiated with ultraviolet rays without being irradiated with ultraviolet rays, and the adhesive strength was lost. It changes into the sheet-like member 71 which consists of the non-adhesion layer 71b. Here, the air flow rate detection chip 20 prepared in advance is bonded together. This completes the mounting structure of the air flow rate detection chip 20 in the air flow rate measuring device 101 as shown in FIG.

  FIGS. 6A to 6E are cross-sectional views for each process showing another method for forming a mounting structure in the air flow rate measuring apparatus 101 of FIG.

  First, as shown in FIG. 6A, a semiconductor wafer 40 on which each structure of the air flow rate detection chip 20 is formed is prepared, and the whole is made of an ultraviolet peeling adhesive on the back side of the semiconductor wafer 40. A sheet-like member 74 made of the adhesive layer 74a is bonded. Next, as shown in FIG. 6B, a predetermined portion of the sheet-like member 74 is masked with a mask M2, and the sheet-like member 74 is selectively irradiated with ultraviolet rays. As a result, as shown in FIG. 6 (c), the sheet-like member 74 of FIG. 6 (a) was irradiated with ultraviolet rays and the adhesive layer 71a having adhesive strength without being irradiated with ultraviolet rays, and the adhesive strength was lost. It changes into the sheet-like member 71 which consists of the non-adhesion layer 71b. Next, the semiconductor wafer 40 is cut together with the sheet-like member 71 at a predetermined position indicated by a broken line B in the drawing, and individual air flow rate detection chips 20 are cut out. Next, as shown in FIG. 6 (d), the air flow rate detection chip 20 with the sheet-like member 71 bonded to the back side is bonded to the substrate member 80. Thus, as shown in FIG. 6E, the mounting structure of the air flow rate detection chip 20 in the air flow rate measuring device 101 is completed.

  In the mounting structure forming method shown in FIG. 6, the sheet-like member 71 is shared as a dicing tape for the semiconductor wafer 40, so that the cost can be reduced.

  FIGS. 7A to 7C are cross-sectional views for each process showing another forming method.

  First, as shown in FIG. 7A, a sheet-like member 75 made of an adhesive layer 75a having a function of losing adhesive force by irradiation with X-rays or the like that can pass through a thin semiconductor is placed at a predetermined position on a substrate member 80. Paste to. Next, the air flow rate detection chip 20 prepared in advance is bonded. Next, as shown in FIG. 7B, the entire surface is irradiated with X-rays without a mask. As a result, as shown in FIG. 7C, the sheet-like member 75 of FIG. 7A has an adhesive layer 75a that is not irradiated with X-rays at the thick portion of the semiconductor chip 20a and remains adhesive, and the membrane. The sheet-like member 76 is composed of a non-adhesive layer 75b that has passed through 20e and is irradiated with X-rays and has lost its adhesive strength. Thus, the mounting structure of the air flow rate detection chip 20 in the air flow rate measuring device 105 shown in FIG. 7D is completed.

  FIG. 8 is a cross-sectional view of one process showing another forming method in the case of using the sheet-like member 75 that loses the adhesive force by irradiation with the X-ray or the like.

  7A to 7C, after the air flow rate detection chip 20 is bonded to the sheet-like member 75, X-rays are irradiated. On the other hand, in the forming method shown in FIG. 8, another forming method in the case of using the sheet-like member 75 that loses the adhesive force by irradiation with the X-ray or the like is used as the mask for X-ray irradiation. Used: an adhesive layer 75a that is not irradiated with X-rays at the thick part of the semiconductor chip 20a and has an adhesive force, and a non-adhesive layer 75b that has passed through the membrane 20e and is irradiated with X-rays to lose the adhesive force. The sheet-like member 77 is formed. In this case, it is possible to arbitrarily set the area occupied by the adhesive layer 75a in the sheet-like member 77 by appropriately setting the height of the air flow rate detection chip 20 from the substrate member 80.

  For the sheet-like member in which the adhesive layer is partially formed, for example, a light delayed curable adhesive can be used in addition to the above-described material that loses the adhesive strength by irradiation with ultraviolet rays or X-rays. The light delayed curable adhesive is an adhesive that does not instantaneously cure by ultraviolet irradiation but cures with a delay. In the case of using this adhesive, after the ultraviolet ray is irradiated to the bonded portion, the air flow rate detection chip is mounted and mounted by holding for a certain time. The advantage of using a light curable adhesive is that the height, flatness, and flatness of the air flow detection chip can be adjusted before complete curing occurs.

  As described above, the mounting structure of the air flow rate detection chip is a mounting structure of the air flow rate detection chip on the board member, and the air flow rate detection part of the air flow rate detection chip is hardly subjected to stress, and is highly accurate. The air flow rate can be detected and high reliability can be ensured, and the mounting structure of the air flow rate detection chip that can easily manufacture and reduce the manufacturing cost can be obtained. Therefore, the mounting structure of the air flow rate detection chip described above is suitable for use in a vehicle-mounted air flow rate detection device that is required to be highly accurate and highly reliable and inexpensive.

1 is a schematic cross-sectional view showing a main part of an air flow measuring device (air flow meter) 100 as an example of a mounting structure of an air flow detecting chip according to the present invention. (A), (b) is an example of another mounting structure, and is typical sectional drawing which shows the principal part of the air flow measuring devices 101 and 102, respectively. In another example, it is a schematic cross-sectional view showing a main part of the air flow rate measuring device 103. FIG. 6 is a diagram illustrating a preferred mounting example of the air flow rate detection chip 20, and FIG. 5A is a schematic cross-sectional view illustrating a main part of the air flow rate measurement device 104. Moreover, (b) is a figure which shows the mounting method of (a). (A)-(d) is sectional drawing according to the formation process of the mounting structure in the air flow measuring device 101 of Fig.4 (a). (A)-(e) is sectional drawing according to process which showed another formation method of the mounting structure in the air flow measuring device 101 of Fig.4 (a). (A)-(c) is sectional drawing according to process which showed another formation method. It is sectional drawing of one process which shows another formation method in the case of using the sheet-like member 75 which loses adhesive force by irradiation, such as X-rays. (A) is sectional drawing which shows the thermal type air flow sensor 1 disclosed by patent document 1. FIG. Further, (b) is an enlarged view around the semiconductor sensor element 2 in (a).

Explanation of symbols

1,100-105 Air flow rate measuring device 2,20,21 Air flow rate detection chip 20a, 21a Semiconductor chip 20b, 21b Air flow rate detection unit 20c Pad unit 20d, 21d Groove 20e, 21e Membrane 70-77 Sheet-like member 70a-75a Adhesive layer 70b-72b, 75b Non-adhesive layer 70c Base film 72c Bead 80 Substrate member

Claims (10)

A mounting structure of an air flow rate detection chip on a substrate member,
The air flow rate detection chip is an air flow rate detection chip in which an air flow rate detection part is formed at one end on the main surface side of the semiconductor chip and a pad part for wire bonding is formed at the other end. Yes,
A sheet in which an adhesive layer is partially formed in a region below the pad portion excluding the air flow rate detection unit, and having a larger area than the air flow rate detection chip between the air flow rate detection chip and the substrate member. Interposing a member,
A mounting structure of an air flow rate detection chip, wherein the air flow rate detection chip is placed on the sheet-like member and joined to the substrate member by an adhesive layer of the sheet-like member.   The air flow rate detection chip mounting structure according to claim 1, wherein the sheet-like member is a tape-like sheet-like member in which the adhesive layer is formed on a base film.   The mounting structure for an air flow rate detecting chip according to claim 2, wherein the adhesive layer is made of an ultraviolet peeling adhesive. The entire sheet-like member is made of an ultraviolet peelable adhesive,
The adhesive layer is a portion of the ultraviolet peelable adhesive that is not irradiated with ultraviolet rays,
The air flow rate detection chip mounting structure according to claim 1, wherein the remaining portion of the sheet-like member excluding the adhesive layer is a portion irradiated with ultraviolet rays of the ultraviolet peelable adhesive.   The air flow rate detection chip mounting structure according to claim 4, wherein beads having the same size are contained in the UV-peelable adhesive of the sheet-like member. The air flow rate detection chip is
A groove is formed on the back surface side of the semiconductor chip, a membrane is formed on the main surface side by the groove, and the air flow rate detection chip is formed by arranging the air flow rate detection unit around the membrane. The mounting structure of the air flow rate detection chip according to any one of claims 1 to 5. The air flow rate detection chip is
It is an air flow rate detection chip in which a groove is formed from the main surface side of the semiconductor chip, a membrane is formed on the main surface side by the groove, and the air flow rate detection unit is arranged around the membrane. The mounting structure of the air flow rate detection chip according to any one of claims 1 to 5.   The surface on the main surface side of the air flow rate detection chip and the surface of the substrate member surrounding the air flow rate detection chip are set at the same height. The mounting structure of the air flow rate detection chip according to the item. A cover covering the air flow rate detection chip,
On the air flow rate detection chip or the substrate member, a partition wall is provided that partitions an air flow path space to which the air flow rate detection unit belongs and a circuit space in which a circuit board connected to the pad unit is arranged. ,
9. The air flow rate detection chip mounting structure according to claim 1, wherein the circuit space is filled with a sealing material, and the circuit board is embedded in the sealing material.   The mounting structure of the air flow rate detection chip according to any one of claims 1 to 9, wherein the mounting structure of the air flow rate detection chip is used in an in-vehicle air flow rate detection device.

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