JPH02288245A - Packaging method of electronic component and packaged board device - Google Patents

Abstract

PURPOSE:To make an entire board small and thin and to enable high-density packaging of an electronic component on a circuit board by a method wherein one end part of each of metal leads in a plurality is bonded beforehand to a bonding pad formed on a chip and the other end part of each of the metal leads is bonded sequentially to a land on the board. CONSTITUTION:One end of each of metal leads 3 is inner-bonded beforehand to each of all bonding pads 2 disposed along the inner periphery of an IC chip on the fitting surface side thereof. In a state wherein the IC chip 1 to which the metal leads 3 are bonded is mounted on a COB circuit board for fitting the IC chip, the other end of each of the metal leads connected to the IC chip is outer-bonded to each of bonding lands 7 formed on the COB circuit board 6. A package structure wherein junction is made by outer-bonding each of the metal leads 3 of the IC chip sequentially to each of the lands 7 on the circuit board 6 is attained, and thereby it is realized that the board is made to be small in size and of low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to improvements in circuit boards on which electronic components such as integrated circuit (hereinafter referred to as IC) chips are mounted.

(Prior Art) Conventionally, when mounting an IC chip on a circuit board, the following method has been widely used.

For example, there is a method in which an IC chip is sealed in a package made of ceramic or plastic, and the package is soldered to an electronic circuit board together with other components (L, C, R). Also, so-called tape automated boning is used to form IC components by bonding IC chips to lands formed on a tape-shaped film by thermocompression bonding or the like.
ding IC etc. is also one of the above-mentioned mounting methods.

Also, there is so-called COB (Chip board), in which IC chips are bonded or wire bonded to an electronic circuit board, and other components are soldered later.
There is a board.

FIG. 13 is a side view showing a state in which an IC chip is mounted on a circuit board by the method described above. circuit board 10
0, the IC chip 101 is firmly bonded to the land for mounting, and wires 1 are bonded to the bonding pads 102 to 102 formed on the top surface of the IC chip 101.
One ends of wires 04 to 104 are inner bonded, and the other ends of wires 104 to 104 are outer bonded to bonding lands 103 to 103 on circuit board 100. This connects the circuit of the IC chip 101 to the lands on the circuit board.

(Problems to be Solved by the Invention) However, although the above-mentioned soldering of packaged ICs makes it possible to mount IC chips at low cost, it is difficult to reduce the overall size of the board. There are problems that hinder high-density mounting, and mounting methods using COB circuit boards enable miniaturization, but have contradictory problems, such as being disadvantageous in terms of cost reduction.

To explain COB circuit boards in more detail, one of the major reasons why it is difficult to reduce costs is the I
One example of this is that it is difficult to repair any malfunctions that occur when C is bonded. That is, a COB circuit board on which an IC chip is mounted must be discarded along with the other complete components if there is a malfunction or a mistake in any one of the board, IC, and bonding work.

In addition to the above methods, there is a flip-chip mounting method that is advantageous in terms of mounting space on an electronic circuit board. Since the process for mounting on the board is complicated, it has been impossible to reduce costs, and it has not been possible to solve the problem.

(Means for Solving the Problems) The present invention was made for the purpose of solving the above-mentioned problems, and its feature is that a chip on which a semiconductor integrated circuit or the like is formed is connected to a land on a substrate. When bonding to the chip, one end of a plurality of metal leads is bonded in advance to a bonding pad formed on the chip,
The electronic component mounting method includes sequentially bonding the other end of the metal lead to the land on the substrate.

Other features of the present invention include a chip that constitutes an integrated circuit and has a plurality of bonding pads formed thereon, a circuit board for mounting the chip, and bonding pads of the chip on the circuit board. It consists of a plurality of metal leads for bonding to the land, and the metal leads are a plurality of metal leads arranged in parallel at the pitch where the bonding pads are formed, and are bundled with an insulating film. The circuit board device is comprised of a group of leads.

(Function) This provides a semiconductor component mounting board device that can be downsized to the same level as a COB board and can be realized at a low cost comparable to the soldering method of packaging ICs.

(Example) The electronic component mounting method and mounting board device according to the present invention will be described below with reference to the figures, taking as an example the case where an IC chip is mounted on a circuit board.

Fig. 1 is a plan view showing a circuit board on which an IC chip is mounted using the mounting method of the present invention, and Fig. 2 shows a state in which metal leads are bonded to the IC chip prior to mounting the IC chip on the circuit board. 3 is a side view of the same, FIG. 4 is a side view of the IC chips shown in FIGS. 1 to 3 bonded to lands on a COB circuit board, and FIG. 5 is a side view of FIG. FIG. 3 is a side cross-sectional view showing a state in which an IC chip that has been completely mounted on a COB circuit board is covered with a resin.

In each figure, 1 is an IC chip, and 2 to 2 are bonding pads to which the IC chip 1 is attached, which are arranged along the inner periphery of the surface. As is clear from FIGS. 2 and 3, metal leads 3 to 3 are inner-bonded in advance to all of these bonding pads 2 to 2 at one end. The other end of the metal leads 3 to 3 is connected to the IC chip 1.
The bonding is performed on a bonding land 7 formed on a COB circuit board 6 for mounting, which will be described later.

As shown in each figure, each metal lead is connected to a polyimide film 4 by connecting a plurality of metal leads 3 to 3 arranged in parallel corresponding to the arrangement of the bonding pads 2 to 2 on each side of the IC chip 1. Lead groups 5 to 5, which are fixed by leads 5 to 4, are provided for each of the sides.

Further, as shown in FIG. 4, the IC chip 1 to which the metal leads 3 to 3 are bonded is mounted on a CO
When mounted on the B circuit board, the other ends of the metal leads connected to the IC chip are outer-bonded to bonding lands 7 to 7 formed on the COB circuit board 6, respectively.

Then, as shown in FIG. 5, the ICC chip that has been completely mounted on the COB circuit board 6 is further covered with an overcoat 8 made of resin or the like to be sealed from the outside. Further, on the COB circuit board 6, extended lands are formed for mounting other circuit components.
Other components such as a chip component 9, a printed resistor 10, etc. can also be mounted together.

Then, connect each metal lead 3 to 3 of the IC chip 1 to the circuit board 6.
It has a mounting structure in which it is joined by sequential outer bonding to the upper bonding lands 7 to 7,
This has achieved miniaturization and low cost.

More specifically, as shown in FIG.
3 to the bonding pads 2 to 2 on the ICC chip, gold bumps 11 are used and placed at each inner bonding part, thereby achieving almost the same bonding conditions as wire bonding on the IC chip 1 side. The metal leads 3 to 3 can be connected under certain conditions.

Inner bonding of the metal leads 3 to 3 to the bonding pads 2 to 2 on the ICC chip is performed one by one in sequence.

In the above manner, as shown in FIG.
are mounted on the bonding lands 7-7 on the circuit board 6 via the metal leads 3-3.

Here, to give an example of actual numerical data for each part, as shown in Fig. 6, bonding pads 2 to 1, which serve as electrode contacts, are formed on the mounting surface of the ICC chip, 1°4m square.
2 are made of rectangular aluminum and have a square shape of 100 μm, and are arranged at a pitch of 200 μm along the upper periphery of the ICC chip.

FIG. 7 is a plan view showing metal leads 3 to 3 for wiring on the circuit board 6 mounted on the ICC chip. In the figure, the metal leads 3 to 3 have a thickness of, for example, 35 μm.
This is a copper lead with a m9 width of 80 μm and is plated with gold to a thickness of 5 μm.

Further, as described above, each lead is fixed with a film 4 made of polyimide or the like in a state in which a plurality of leads are arranged in parallel. Gold bumps 11 to 11 formed by gold balls of Φ80 g, m, for example, are placed at the tips of each of the leads 3 to 3 and heated to a predetermined temperature (350'C) by a temporary bonding head 12. , pressure (50g)
It is temporarily fixed by applying for a predetermined period of time (for example, 0.2 seconds). Further, if projections are formed at the tips of these bumps 11 to 11, when bonding to the aluminum bonding pads 2 of the IC chip 1, misalignment is less likely to occur and the bonding yield is improved.

FIG. 8 is a side view for explaining the process of temporarily fixing the gold bump 11 to the metal lead 3 described above, using a positioning tool that has a recess 13a formed at the position where it will be bonded to the bonding pad 2 on the IC chip 1. Using the tool 13, with the gold bump 11 positioned in each recess 13a, the above-mentioned heat and pressure are applied using the bonding head 12 for temporary fixing,
A gold bump 11 is temporarily fixed to the metal lead 3.

Next, when fixing the metal lead 3 to which the gold bump 11 shown in FIG. 8 is temporarily fixed to the bonding pad 2 of the IC chip 1, as shown in FIG. With the gold bump 11 of the lead 3 aligned, the bonding head 14 is applied from above the metal lead 3, and the metal lead 3 is bonded to the inner layer by applying ultrasonic waves at a predetermined temperature, pressure, and predetermined frequency. Bonding.

Next, the IC chip 1 with the metal leads 3 attached is mounted on the COB circuit board 6.
The circuit board 6 is made of A1□0396% ceramic with a thickness of 20μ.
IC is plated with Cu of m and later etched.
A pattern of bonding lands 7 to 7 for bonding the chip 1 is formed. Further, the bonding lands 7 to 7 are plated with gold (Au) with a thickness of 3 μm.

When the IC chip is mounted on a COB circuit board, as shown in FIG.
The outer bonding land 7 is aligned, and heat, pressure, and ultrasonic waves of, for example, 300'C, 50g, and 60KHz are applied for 0.2 seconds by the outer bonding head 15, and the metal leads 3 are sequentially bonded on the COB circuit board 6. Do outer bonding to land 7.

At this time, each lead is bonded sequentially (therefore, it can be mounted without causing bonding defects due to irregularities on the substrate surface or variations in the thickness of the outer bonding, etc.).

In this way, since the structure is such that bonding can be performed sequentially using heat, pressure, and ultrasonic waves, variations in height during bonding can also be absorbed. Compared to the conventional TAB method in which all leads are bonded at the same time in one go, this method reduces the precision in the height direction relative to the board surface during the mounting process, improving both workability and yield. do.

Furthermore, since the bonding work is performed sequentially, when performing inner bonding of the metal lead 3 to the IC chip 1, as shown in FIG.
The mounting work can be carried out by preparing a total of four lead groups in which the metal leads corresponding to the bonding pads 2 to 2 are bundled in parallel with polyimide films 4 to 4 for each side.

In other words, unlike the TAB method, there is no need to create a metal lead group corresponding to the entire bonding pad arrangement for each IC chip (it is highly versatile. In other words, if the pad pitch is the same on an IC chip, Simply prepare metal lead groups in which multiple identical metal leads are arranged in parallel for the number of sides on which the bonding pads of the IC chip are formed. Compared to bonding wire, the amount of gold used can be reduced, and the cost of metal leads can be lowered.

In the above-described bonding work, as shown in FIG. 12, the bonding position between the bonding point 3a of the metal lead 3 and the bonding land 7 on the circuit board is set to the innermost side of the bonding land 7. . As shown in FIG. 11, this is so that when a defect occurs in the operation of the mounted IC chip 1, the mounted IC chip 1 can be removed and other IC chips 1 can be outer bonded after being removed. This is to do so.

An operation test is conducted in this state, and if the function and operation are satisfactory, the module is coated with resin and completed as an electronic circuit module, as shown in FIG.

In the above description, an example of a semiconductor component mounting apparatus according to the present invention has been described, but the present invention can also be applied to a so-called Faceup COB circuit board.

It can also be used in combination with conventionally used wire bonding.

Further, as the COB circuit board, as shown in FIG. 5, in addition to the %IC chip, it is also possible to use a COB circuit board on which a printed resistor or the like is formed.

Furthermore, the material is not limited to A 1 *Os, and other ceramics, PCB, etc. can also be used.

Also, regarding the surface treatment of the bonding land, gold (A
By using other materials such as tin (Sn), the cost can be further reduced.

Further, conductors such as metal leads are not limited to Cu, and may be formed by baking gold or silver.

Furthermore, although the metal leads 3 shown in FIG. 7 are arranged in parallel on both the inner and outer sides at the same pitch, there is no need to be limited to this pattern; for example, as shown in FIG. Alternatively, the outer layer may be formed in a radial pattern with a wide pitch.

Further, in FIG. 10, for convenience of explanation, the case where there is only one bonded IC chip on the COB circuit board has been described, but the present invention is more applicable to the case where a large number of IC chips are mounted on the circuit board. The effect of doing so is huge.

Further, in the above-described embodiment, the present invention was applied to a single-sided mounting type COB circuit board, but the present invention can be similarly applied to a double-sided mounting type.

(Effects of the Invention) As described above, according to the present invention, when mounting a chip such as a semiconductor IC on a COB circuit board, the entire board can be made smaller and thinner, and the circuit board of an electronic device can be made more compact. This enables high-density packaging.

Furthermore, even if a defect occurs in the semiconductor chip, it can be easily repaired, yields are improved, reliability is improved, and costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment in which the electronic component mounting method and mounting board device of the present invention are applied to a circuit board device on which an IC chip is mounted, and FIGS. 2 and 3 show an IC chip and connection leads. Fig. 4 is a side view to explain the structure of mounting the IC chip onto the land on the circuit board, and Fig. 5 shows the mounting structure of the IC chip on the land on the circuit board. 6 is a plan view for explaining the bonding pad of the IC chip, and FIG. 7 is a plan view showing the configuration of the metal lead for connection.
Figures 8, 9, and 10 are side views for explaining the bonding operation of metal leads for connection, Figure 11 is a side view for explaining the IC chip replacement work, and Figure 12 is for connection. FIG. 13 is a plan view showing another embodiment of the metal lead, and a side view for explaining a conventional mounting structure of an IC chip on a circuit board. ×-P +7 outer box (26 ring area outer cover) Ryoin

Claims (5)

[Claims] (1) When bonding a chip on which a semiconductor integrated circuit or the like is formed to a land on a substrate, one end of a plurality of metal leads is bonded in advance to the bonding pad formed on the chip, and other ends of the metal leads are bonded to the bonding pad formed on the chip. A method for mounting an electronic component, characterized in that end portions are sequentially bonded to the lands on the substrate. (2) The electronic component mounting method according to claim (1), wherein the metal leads are bundled in a predetermined number with an insulating film. (3) A chip forming an integrated circuit and having a plurality of bonding pads formed thereon, a circuit board for mounting the chip, and a circuit board for bonding the bonding pads of the chip to bonding lands on the circuit board. The metal lead is made up of a group of leads that are bundled together by an insulating film and are arranged in parallel at a pitch where the bonding pads are formed. A circuit board device characterized by: (4) The circuit board device according to claim (3), wherein the metal leads are bundled with the insulating film for each arrangement of bonding pads on each side of the chip. (5) In claim (3), the bonding land formed on the circuit board has a plurality of bonding portions formed with respect to the metal lead, and the bonding land formed on the circuit board is connected to the metal lead a plurality of times. A circuit board device configured to enable bonding.