Airflow measuring apparatus including a ventilation hole between a connector part and a circuit chamber

Patent metadata

Field	Value
Publication number	US-9587970-B2
Application number	US-201114363235-A
Country	US
Kind code	B2
Filing date	Dec 7, 2011
Priority date	Dec 7, 2011
Publication date	Mar 7, 2017
Grant date	Mar 7, 2017

Abstract

An airflow measuring apparatus includes a sub-passage that takes in part of flow of fluid flowing through an intake pipe, a sensor element disposed in the sub-passage to measure the flow of fluid, a circuit part converting the flow of fluid detected by the sensor element into an electric signal, a connector part connected to the circuit part to output a signal externally, and a casing supporting the sensor element and the circuit part. The sensor element is disposed in the intake pipe, and includes a cavity disposed at a semiconductor substrate and a diaphragm including a thin film part that covers the cavity. The sensor element on a lead frame has surfaces that are mold-packaged with resin so that the diaphragm and part of the lead frame are exposed. One hole is disposed at the lead frame for communication between the cavity and exterior.

First claim

The invention claimed is:

1. An airflow measuring apparatus comprising: a sub-passage that takes in a part of a flow of fluid flowing through an intake pipe; a sensor element that is disposed in the sub-passage to measure the flow of fluid; a circuit part that converts the flow of fluid detected by the sensor element into an electric signal; a connector part having a connector that is electrically connected to the circuit part to output a signal externally; and a casing that supports the sensor element and the circuit part, the sensor element being disposed in the intake pipe, wherein
the sensor element includes a cavity that is disposed at a semiconductor substrate, and a diaphragm including a thin film part that covers the cavity,
the sensor element is mounted at a lead frame,
the sensor element and the lead frame have surfaces that are mold-packaged with resin so that a diaphragm part of the sensor element and a part of the lead frame are exposed to the sub-passage, and
a hole is disposed at the lead frame to facilitate communication between the cavity and exterior of the mold package, and
wherein the airflow measuring apparatus further includes a passage to communicate from the hole disposed at the lead frame to interior of the connector part or an engine room of a vehicle through a flange part via an interior of the lead frame.

2. The airflow measuring apparatus according to claim 1 , wherein
the lead frame and a metal terminal of the connector are made of different members,
at least one space is disposed between a part of the casing that is exposed to the intake pipe and the flange, the space being to join the lead frame that is exposed from the mold package to the metal terminal,
a second hole is disposed to join the space to the connector part or the flange part, and
communication to the space is established from the hole disposed at the lead frame through the interior of the lead frame.

3. The airflow measuring apparatus according to claim 1 , wherein
the lead frame at least includes two members including a first lead frame, at which the sensor element is to be mounted, and a second lead frame that is to be bonded to the first lead frame for adhesion.

4. The airflow measuring apparatus according to claim 3 , wherein
the first lead frame includes a through hole at a position facing an enclosed space that is defined with the first lead frame and the cavity of the sensor element mounted thereon,
a groove is disposed at any one of or both of the bonding face of the first lead frame and the bonding face of the second lead frame, the groove being along a longitudinal direction of the lead frame, and
a passage is defined by bonding the first and the second lead frames.

5. The airflow measuring apparatus according to claim 4 , wherein
the first lead frame includes a groove on the side of the bonding face with the second lead frame and a second through hole at a part of the groove that is away from the through hole, and
the second through hole communicates with exterior of the mold package.

6. The airflow measuring apparatus according to claim 5 , wherein
the second through hole is bored so as to penetrate through a mold part of the mold package toward a direction perpendicular to the sensor-element mounting face or toward a side face direction thereof.

7. The airflow measuring apparatus according to claim 4 , wherein a section of the bonded faces of the first and the second lead frames defines an aperture of the passage to exterior of the mold package.

8. The airflow measuring apparatus according claim 3 , wherein
the first lead frame and the second lead frame of the lead frame are prepared by bending one lead frame.

9. The airflow measuring apparatus according to claim 3 , wherein
the first lead frame comprises glass or silicon.

10. The airflow measuring apparatus according to claim 9 , wherein
the through hole at the rear face of the diaphragm, which is disposed at the first lead frame, is formed by dry etching, wet etching or blasting.

11. The airflow measuring apparatus according to claim 1 , further comprising: a pipe-formed member having one end face that is connected to the hole disposed at the lead frame, wherein
the other end face of the pipe-formed member is open to exterior of the mold package.

12. The airflow measuring apparatus according to claim 1 , wherein
the hole includes a through hole that is disposed at the lead frame at a position facing an enclosed space that is defined with the lead frame and the cavity of the sensor element mounted at the lead frame, and a connection hole to connect to exterior of the mold package, and
the through hole and the communication hole are disposed at a same member and mutually intersect.

13. The airflow measuring apparatus according to claim 1 , wherein
the lead frame includes a dam structure at a periphery of the hole disposed at the lead frame, the dam-structure having a shape along an etching opening shape at the rear face of the diaphragm.

14. A method for manufacturing an airflow measuring apparatus including: a sub-passage that takes in a part of a flow of fluid flowing through an intake pipe; a sensor element that is disposed in the sub-passage to measure the flow of fluid; a circuit part that converts the flow of fluid detected by the sensor element into an electric signal; a connector part having a connector that is electrically connected to the circuit part to output a signal externally; and a casing that supports the sensor element and the circuit part, the sensor element being disposed in the intake pipe, the sensor element including a cavity that is disposed at a semiconductor substrate, and a diaphragm including a thin film part that covers the cavity, the sensor element being mounted at a lead frame, the method comprising:
a first step of mounting the sensor element at the lead frame; and
a second step of performing mold-package of surfaces of the sensor element and the lead frame with resin so that a diaphragm part of the sensor element and a part of the lead frame are exposed,
wherein prior the second step, the method further comprises:
a hole forming step of forming a through hole that is to be disposed at the lead frame at a position facing an enclosed space that is defined with the lead frame and the cavity of the sensor element, and a connection hole to connect to exterior of the mold package,
wherein the hole forming step includes a processing step of forming a groove to form the through hole and the connection hole by etching or pressing, and
wherein the method further comprises:
bending one lead frame to form a first lead frame and a second lead frame as the lead frame;
a passage forming step of, following the hole forming step, bonding the first and the second lead frames to form a passage inside the lead frame; and
following the second step, cutting the passage partially to form an aperture leading to exterior of the mold package.

15. The method for manufacturing an airflow measuring apparatus according to claim 14 , wherein
the hole forming step further includes forming a second through hole at a part of the groove that is away from the through hole, a part of the second through hole being formed with a mold of the mold package.

Assignees

• Morino Takeshi
• Tashiro Shinobu
• Tokuyasu Noboru
• Doi Ryosuke
• Hanzawa Keiji
• Hitachi Automotive Systems Ltd

Inventors

• Morino Takeshi
• Tashiro Shinobu
• Tokuyasu Noboru
• Doi Ryosuke
• Hanzawa Keiji

Classifications

• G01F1/692 Primary

  Thin-film arrangements · CPC title

• F02D41/187

  using a hot wire flow sensor · CPC title

• G01F1/6842 Primary

  with means for influencing the fluid flow · CPC title

• G01F5/00

  Measuring a proportion of the volume flow · CPC title

• G01F1/6845

  Micromachined devices · CPC title