JPS5916122A - Magnetic sensor and its production - Google Patents

Abstract

PURPOSE:To save the labor of connection of lead terminals to prevent the occurrence of connection defects, by molding a chip in a case and grinding the end face on the side of a magnetoresistance element and the end face on the side of a leading-out electrode thereafter and forming a connection terminal by mask vapor-deposition or the like. CONSTITUTION:After a substrate (the chip) where an MR element 11 and electrode parts 12 and 12 are formed is molded in a case 14, and an end face 44 on the side of the MR element and a terminal taking-out face 43 on the opposite side of the case 14 are ground by a both-face grinder or the like to finish these end faces into specular faces. Connection terminal 31 having a C-shaped or channel-shaped pattern are formed by mask vapor-deposition or sputtering so that these terminals 31 are connected to electrode parts 12 on the terminal taking-out face 43, thus obtaining a magnetic sensor. Since connection terminals are connected by vacuum deposition or sputtering, the MR element is prevented from being degraded by heat or the like, and connection defects due to the wire bonding system or the soldering system are not generated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic sensor that utilizes a magnetoresistive effect, and more particularly to a magnetic sensor that has an improved structure in which a magnetoresistive member is attached.

When a constant current is passed through a ferromagnetic material such as a Fe-Ni alloy and a magnetic field is applied to it, the resistance value changes depending on the strength of the magnetic field. In other words, there is a unique relationship between the magnetic field and the resistance value. holds true. This is called the magnetoresistive effect, and magnetic sensors that utilize this effect have come into widespread use in recent years.

Magnetoresistive elements (hereinafter referred to as MR elements) using Fe-Ni etc. have the advantage of high productivity because they can be easily formed using thin film deposition technology similar to the manufacturing of ICs. In the mounting process, there were problems as described below.

FIGS. 1 and 82 show the state in which the MR element is mounted in a conventional magnetic sensor. In FIG. 1, an MR element 11 is thinly deposited on a substrate 13 with electrode parts 12.12 connected to both ends thereof. Furthermore, the electrode part 12.12
Lead terminals (connection terminals) for bonding to other electronic components 15. Zero or more members to which 15 are bonded by wire bonding 16 are attached to at least the board 13 and the lead terminals 15 in the protective case 14. Usually, the molding is done including the bonding part.

The example shown in FIG. 2 has almost the same configuration, but the electrode part 12
．． 12 and lead terminals 15 and 15 are connected by soldering 21.

As mentioned above, in conventional magnetic sensors, lead terminals protruding outside the molding case are provided for connection with other electronic components, so wire bonding is a time-consuming process for connecting the electrodes of the element and the lead terminals. , the number of steps was large because it was done by soldering, etc., and productivity was low. Furthermore, bonding wire breakage and solder defects are likely to occur, resulting in a lack of reliability.

Therefore, the present invention has been made in view of the above problems.
The purpose is to provide a magnetic sensor with simple configuration, high reliability, and high productivity.

In order to achieve the above object, the present invention provides a magnetic sensor in which a chip having a magnetoresistive element and an electrode part coupled thereto is molded into a case, and after the chip is molded into the case, the chip is removed. A method and structure in which the end face on the magnetoresistive element side and the end face on the extraction electrode side are polished, and a connection terminal is formed by bonding to the electrode on the end face of the case substantially perpendicular to the direction in which the electrode portion is extracted, by mask vapor deposition or the like. Adopted.

The present invention will be described in detail below based on embodiments shown in the drawings.

3 and 4 illustrate the method of manufacturing a magnetic sensor according to the present invention, and the same or similar members as in the conventional example are designated by the same reference numerals, and the explanation thereof will be omitted.

First, as shown in Figure $3, the MR element 11 is opened as in the conventional example.
After molding the substrate (hereinafter collectively referred to as a chip) on which the electrode portions 12 and 12 are formed into the case 14, the MR element side end surface 44 of the case 14 and the terminal extraction surface 43 on the opposite side are polished on both sides. Polished with a machine to a mirror finish. However, since the positional accuracy of the MR element 11 affects its performance, this polishing accuracy must be performed extremely precisely.
In the polishing step 3, the dimensions are determined using the MR element side end surface 44 as a reference.

In addition, as will be described later, since a connection terminal is formed by electrically coupling the electrode portion 12.12 to this terminal extraction surface 43, the cross section of the electrode portion 12.12 becomes a mirror surface on the same plane as the terminal extraction surface 43. Of course, you can finish it like this.

Next, as shown in FIG. 4, connection terminals 31, 31 are formed in a pattern such as C-shape or U-shape by bonding to the electrode parts 12, 12 facing the terminal extraction surface 43 and using mask vapor deposition or sputtering. A completed magnetic sensor is obtained by forming the magnetic sensor.

At this time, the connection terminals 31 , 31 are formed not only in the above-mentioned manner, but also in the electrode portions 12 facing the terminal extraction surface 43 by wireless bonding using ultrasonic bonding of metal foil.
．． 12 may be provided.

The magnetic sensor constructed by the above method is different from the magnetic sensor constructed by the conventional method, but if the soldering method shown in Fig. 2 is used, the joint will be damaged due to stress strain due to thermal expansion. In contrast, the wire bonding method shown in Figure 1 is prone to breakage of the bonding wire due to vibration, etc., whereas the connection terminals are bonded by vacuum evaporation or sputtering.
Since the MR element does not deteriorate due to heat or the like, and connection failures as described above do not occur, reliability as a magnetic sensor can be significantly improved.

As is clear from the above description, according to the present invention, in a magnetic sensor formed by molding a chip having a magnetoresistive element and an electrode part coupled thereto in a case,
After the chip is molded in a case, the end face of the chip on the magnetoresistive element side and the end face on the lead-out electrode side are polished and bonded to the electrode on the end face of the case that is substantially perpendicular to the lead-out direction of the electrode section to form a mask. Since the method and structure of forming the connection terminals by vapor deposition or the like are adopted, there is an excellent effect that a magnetic sensor with high reliability and productivity can be easily provided.

[Brief explanation of the drawing]

1 and 2 are perspective views for explaining the structure of a conventional magnetic sensor, and FIGS. 3 and 4 are perspective views for explaining the structure and manufacturing method of the magnetic sensor of the present invention. 11... MR element 12... Electrode section 13...
Board 14...Case Figure 2

Claims (3)

[Claims] (1) In a magnetic sensor in which a chip having a magnetoresistive element and an electrode part coupled thereto is molded into a case, the chip is connected to the end face of the case substantially perpendicular to the direction in which the electrode part is pulled out by mask deposition or the like. A magnetic sensor characterized by forming a terminal. (2) The magnetic sensor according to claim 1, wherein the connection terminal is a metal foil bonded to the end surface by ultrasonic bonding. (3) After molding a chip having a magnetoresistive element and an electrode part coupled thereto in a case, polishing the end face of the chip on the magnetoresistive element side and the end face on the extraction electrode side; and this polishing step. A method for manufacturing a magnetic sensor, comprising the step of forming a connection terminal by bonding to the electrode facing the end surface on the electrode side.