JP2013183094A - Mounting method for electronic component, and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mounting method for an electronic component that has high reliability of joining while making a joining temperature low.SOLUTION: A mounting method for an electronic component includes a dispersion procedure for dispersing and arranging Bi particles on a table, a press-contacting procedure for bringing the Bi particles into press contact with a solder ball by pressing the solder ball containing much tin against the table, a pressing procedure for pressing the solder ball having the Bi particles in press contact against a terminal, and a joining procedure for performing a heat treatment for joining the terminal and solder ball together at a temperature of 160-200°C while the terminal and solder ball are pressed by the pressing procedure.

Description

  The present invention relates to an electronic component mounting method and a semiconductor device.

  As a method for mounting an electronic component on a circuit board such as a printed board, a mounting method by soldering is widely used. At this time, for example, a solder bump is used to solder an electronic component having a plurality of terminals and a narrow pitch, such as an LSI (Large Scale Integration), to a circuit board.

  Soldering processing using solder bumps (hereinafter referred to as bump bonding processing) is performed by pressing a solder bump previously connected to a terminal of an electronic component against a terminal formed on a circuit board and performing a heat treatment while maintaining this state. (Patent Documents 1 to 5). Note that a solder having a Sn (tin) -rich Sn-3.0 mass% Ag-0.5 mass% Cu composition is often used for the bump bonding process.

  As a related technique related to bump bonding processing, Patent Document 1 discloses that a solder ball is pressed against a thin film of flux containing metal powder with good solder wettability, and breaks through an oxide film formed on the surface of the solder ball. Thus, a technique for biting metal powder is disclosed.

  Patent Document 2 discloses a solder paste flux containing one or more of tin, copper, zinc, silver, antimony, lead, indium, bismuth, nickel, aluminum, gold, and germanium.

  Further, Patent Document 3 discloses a technique for polishing a solder ball flatly by mechanical polishing or chemical polishing. Patent Document 4 discloses that bump bonding is performed by heat treatment at a predetermined temperature. Patent Document 5 discloses a technique for lowering the bonding temperature using a solder bump having a Sn—Bi—Ag composition.

JP 2006-073976 A JP 2011-121059 A JP 2007-110104 A JP 2011-210819 A JP 2006-128493 A

However, the bump bonding according to the related art has a problem that the reliability of the bump bonding is low as described later.
That is, when the bonding temperature is lowered, the solder bumps are not completely melted and a bismuth-rich structure may be generated. However, since bismuth is a hard and brittle metal, the bismuth rich region is vulnerable to impact. Therefore, when external vibration or the like is applied to the joining portion, a joining failure is likely to occur, and highly reliable bump joining cannot be performed.

  Accordingly, a main object of the present invention is to provide an electronic component mounting method and a semiconductor device with high bump bonding reliability while reducing the bonding temperature.

  In order to solve the above-described problem, a mounting method of an electronic component for connecting terminals to each other includes a dispersing procedure for dispersing and arranging Bi particles on a table, and pressing a solder ball containing a large amount of tin on the table so that a predetermined ratio is applied to the solder ball. The crimping procedure for crimping the Bi particles, the pressing procedure for pressing the solder balls crimped with Bi particles to the terminals, and the terminals and the solder balls are pressed between 160 ° C. and 160 ° C. in a state where the terminals and the solder balls are pressed by the pressing procedure. And a joining procedure for performing a heat treatment for joining at a temperature of 200 ° C.

  Further, in the semiconductor device in which the electronic component having the connection terminal is mounted on the terminal of the circuit board by the solder bump, the terminal of the electronic component and the terminal of the circuit board are joined by the electronic component mounting method described above. It is characterized by that.

  According to the present invention, Bi particles are scattered and pressed against a solder ball, so that Bi particles necessary for bump bonding are unevenly distributed at the bonding portion, and reliability is reduced while reducing the bonding temperature at the time of bonding. High bump bonding is possible.

It is sectional drawing of the solder bump concerning the 1st Embodiment of this invention. It is a flowchart which shows the mounting method of an electronic component. It is a side view of the table which disperse | distributed Bi particle | grains. It is a figure which shows the mode at the time of carrying out dispersion | distribution arrangement | positioning of Bi particle | grains on a table, (a) is a top view of the table which carried out dispersion | distribution arrangement | positioning of Bi particle | grains, (b) is the cross section of the table at the time of carrying out dispersion | distribution arrangement | positioning of Bi particle | grains using a mask. FIG. 4C is a cross-sectional view of the table when the mask is removed. FIG. 2 is a diagram showing a state in which Bi particles are pressure-bonded to a solder ball, where (a) is a cross-sectional view when an electronic component is opposed to a table, (b) is a cross-sectional view when a solder ball is pressed against Bi particles, c) is a cross-sectional view of a solder ball when bonded to Bi particles. It is a figure which shows the mode at the time of joining using a solder bump, (a) Sectional drawing at the time of making an electronic component oppose a circuit board, (b) is sectional drawing at the time of pressing a solder ball on the terminal of a circuit board (C) is sectional drawing which shows a joining state. It is a figure which shows the mounting method of the electronic component concerning the 2nd Embodiment of this invention, (a) is a top view of the table provided with a substantially square recessed part, (b) is the table at the time of embedding Bi paste in a recessed part. Sectional drawing, (c) shows a sectional view of the table after Bi paste is embedded in the recess. It is a top view of a table provided with the rectangular recessed part concerning 2nd Embodiment.

  Next, an embodiment of the present invention will be described. FIG. 1 is a cross-sectional view of a solder bump 2 according to the present embodiment. The solder bump 2 is formed by a solder ball 3 and Bi particles 4 pressed onto the solder ball 3. The solder ball 3 is a solder whose main material is Sn-3.0 mass% Ag-0.5 mass% Cu, and has a truncated crushed shape in which a sphere is roughly crushed. The upper and lower surfaces form a product side surface 3a to which the electronic component 10 is connected, and a substrate side surface 3b to which Bi particles 4 are pressure-bonded in the vicinity region.

  A method of manufacturing such a solder bump 2 will be described with reference to FIGS. FIG. 2 is a flowchart showing a method for manufacturing the solder bump 2. 3 to 5 are side views of the solder bumps 2 and the like showing a state during the production.

  Step S1: First, as shown in FIGS. 3 and 4A, the Bi particles 4 are distributed and arranged on the table 6 such as a work table so as to satisfy the following relationship with respect to the solder balls 3. It is also possible to disperse and arrange Bi paste containing Bi particles 4 on the table 6.

Now, when the average diameter D2 of the Bi particles 4 to be used and the average diameter D1 of the solder balls 3 satisfy the relationship of Formula 1, good bonding can be performed.
D2 = n × D1 (1)
Here, n is a proportional coefficient, and is set so as to satisfy the relationship of the following Expression 2.
0.02 ≦ n ≦ 0.2 (2)
In addition, when the range of the proportional coefficient n is in the range of 0.06 ≦ n ≦ 0.1, better bump bonding can be performed.

  For example, when the diameter D1 of the solder ball 3 is 500 μm and n = 0.06, the average diameter D2 of the Bi particles 4 is D2 = n × D1 = 0.06 * 500 = 30 μm. Therefore, if the Bi particles 4 having an average particle size of 30 μm (20 to 40 μm) are used, good bump bonding can be performed. Of course, it is preferable that the particle size variation of the Bi particles 4 is small.

At this time, the number m of Bi particles 4 to be pressure-bonded to the solder ball 3 is 1 ≦ m ≦ 0.2 / n ² = 0.2 / (0.062) ≈55 when n = 0.06. . If the number of Bi particles 4 to be pressure-bonded is too small, the amount of Bi particles 4 to be melted will be small, making it difficult to achieve good bump bonding. On the other hand, when the amount of Bi particles 4 increases, the amount of Bi particles 4 remaining in the bonding region at the time of completion of bonding increases, and the reliability of bump bonding may be reduced.

  However, by setting the proportionality coefficient n so as to satisfy Equation 2, excess or deficiency in the amount of Bi particles 4 does not occur, and a decrease in the reliability of bump bonding can be prevented.

  For example, a method as shown in FIG. 4 can be used as a method for distributing the amount of Bi particles 4 thus determined in the table 6.

  First, a mask 40 having a plurality of openings 41 formed at a constant pitch is placed on the table 6 (see FIG. 4A). Examples of the mask 40 include a mask having a thickness of 30 μm, an opening diameter of 40 μm, and a pitch of 50 μm.

  Then, a Bi paste 5 containing Bi particles 4 is put on the mask 40, and the Bi paste 5 is squeezed using a squeegee 42 (see FIG. 4B). Thereby, the Bi paste 5 is embedded in the opening 41. Note that only the Bi particles 4 may be used instead of the Bi paste 5.

  Thereafter, when the mask 40 is peeled off, a certain amount of Bi paste 5 is dispersedly arranged on the table 6 as shown in FIG.

  Step S2: The electronic component 10 is aligned with the table 6 so as to face each other (see FIG. 5A).

  Step S3: In this state, the electronic component 10 is brought close to the table 6 and the solder ball 3 is pressed against the Bi particle island 4a. At this time, since an oxide film may be formed on the surface of the solder ball 3, it is pressed while scrubbing. The oxide film is removed by this scrubbing operation.

  As described above, it is possible to form the solder bump 2 in which a predetermined amount of Bi particles 4 are pressure-bonded to the solder ball 3 (see FIG. 5C).

  The electronic component 10 on which the solder bumps 2 are thus formed is aligned with the terminals 32 formed on the circuit board 31 (see FIG. 6A) and pressed (see FIG. 6B). ).

  And the heat processing for joining is performed in this state (refer FIG.6 (c)). The heat treatment for bonding is performed in a range of 160 ° C. to 200 ° C., for example, 180 ° C. Since the Bi particles 4 are unevenly distributed in the vicinity of the substrate side surface 3b with the circuit board 31, even if they are bonded at a low temperature, almost all of the Bi particles 4 contribute to the bonding. That is, since the generation of residual Bi particles that do not contribute to the bonding can be suppressed, a reduction in impact resistance due to the residual Bi particles can be prevented. Therefore, it is possible to increase the reliability of the bonding while reducing the bonding temperature.

<Second Embodiment>
Next, a second embodiment of the present invention will be described. In addition, about the same structure as 1st Embodiment, description is abbreviate | omitted suitably using the same code | symbol.

  In the first embodiment, a predetermined amount of Bi particles is pressed onto a solder ball by embedding Bi particles in the opening of the mask.

  On the other hand, in this embodiment, Bi particles of a predetermined amount are dispersed and arranged by embedding Bi particles in a table having concave portions formed at a predetermined pitch.

  FIG. 7 shows the table 6 having a substantially square recess 33, and FIG. 8 shows the table 6 having a rectangular recess 33. A plurality of such rectangular recesses 33 are provided. In addition, the shape of the recessed part 33 is not limited to these, For example, circular shape may be sufficient.

  Then, the Bi paste 5 is put into the recess 33 and is stirred by the squeegee 42 or the like. Thereby, a predetermined amount of Bi paste 5 can be embedded in each recess 33, and a predetermined amount of Bi particles 4 can be embedded in the solder balls 3.

2 Solder bump 3 Solder ball 4 Bi particle 5 Bi paste 6 Table 10 Electronic component 31 Circuit board 32 Terminal 33 Recess 40 Mask 41 Opening 42 Squeegee

Claims (8)

An electronic component mounting method for mounting an electronic component by bonding with solder bumps connecting terminals,
A dispersion procedure for dispersing and arranging Bi particles on the table;
A pressing procedure in which a solder ball containing a large amount of tin is pressed against the table, and a predetermined proportion of the Bi particles are pressed onto the solder ball;
A pressing procedure for pressing the solder balls to which the Bi particles are pressed against the terminals;
A joining procedure for performing a heat treatment for joining the terminal and the solder ball at a temperature of 160 ° C. to 200 ° C. in a state where the terminal and the solder ball are pressed by the pressing procedure;
A method for mounting an electronic component, comprising: The electronic component mounting method according to claim 1,
The dispersion procedure includes a procedure of placing a mask having an opening of a predetermined shape on the table and embedding the Bi particles or Bi paste containing Bi particles in the openings. . The electronic component mounting method according to claim 1,
The electronic component mounting method, wherein the dispersing step includes a step of embedding the Bi particles or Bi paste containing Bi particles in a recessed portion having a predetermined shape formed on the table. The electronic component mounting method according to claim 1,
According to the pressing procedure, the solder ball on the side to which the Bi particles are pressed is formed into a flat surface. The electronic component mounting method according to any one of claims 1 to 4,
An electronic component mounting method comprising: a step of pressing the solder ball while scrubbing the solder ball when pressing the solder ball against the table. An electronic component mounting method according to any one of claims 1 to 5,
When the diameter of the solder ball is D1 and the average diameter of Bi particles is D2, the average diameter D2 of the Bi particles is obtained by multiplying the diameter D1 of the solder ball by a proportional coefficient n, and the proportional coefficient n Satisfies 0.02 ≦ n ≦ 0.2. A method for mounting an electronic component, wherein: The electronic component mounting method according to claim 6,
An electronic component mounting method characterized in that the number of Bi particles satisfies a range of 1 ≦ m ≦ 0.2 / n ² where m is the number of Bi particles pushed into the solder ball. A semiconductor device in which an electronic component including a connection terminal is mounted on a terminal of a circuit board by a solder bump,
8. A semiconductor device, wherein a terminal of the electronic component and a terminal of the circuit board are joined by the electronic component mounting method according to claim 1.

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