JPS5827350A - Mounting method for ic - Google Patents

Abstract

PURPOSE:To omit the process of bonding in advance a circuit substrate to a backing plate and to reduce the size and thickness of an IC by bonding the substrate to the plate when sealing resin hardens. CONSTITUTION:A backing plate 2 which is formed of a sheet made of metal or resin is contained in the recess 1a of a carrier 1. A circuit pattern 3c is arranged on a circuit substrate 3, a device hole 3b passed to bury an IC is opened, a plurality of positioning holes 3a are formed, and the pin 1b of the carrier 1 is engaged. A thermosetting resin adhesive 5 is dropped to the surface of the plate 2 in the hole 3b, and the IC 4 is carried and bonded. Then, the connecting electrode and the pattern 3c of the IC are connected with a wire 6, is sealed with sealing resin 7, and is hardened. In this case, the resin 7 is filled in a gap 8, reaching the plate 2 on the bottom of the gap 8, and is flowed also to the gap 9 between the substrate 3, and the plate 3, is hardened and is bonded fixedly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a thin mounting method for semiconductor devices. In order to further reduce the size and thickness of small devices such as wristwatch modules, there is an increasing demand for smaller and thinner mounting structures for semiconductor elements.

After fixing a semiconductor element to a circuit board on which a copper foil is pasted on a heat-resistant resin substrate and circuit turns are formed by photoetching, an external connection electrode on the semiconductor element is connected to the circuit board using an Au wire or an Al wire. In the so-called wire bonding method for connecting the corresponding patterns on the circuit board,
As a method of achieving thinness, a through hole is previously formed by pressing or other means in order to mount a semiconductor element on a circuit board, and a backing plate made of a different thin plate material is fixed to the side opposite to the circuit pattern. A method of fixing the semiconductor element on the backing plate has been put into practical use. By adopting this method, the semiconductor can be fixed while being dropped into the recess provided in the circuit board, so the wires can be fixed. The mounting structure formed by the bonding method is made thinner by the depth of the recess (and as a result, the amount of wire protruding in the plane direction can be reduced, so the mounting area of the semiconductor element can be reduced by that amount). can.

However, the drawbacks of the above-mentioned conventional methods are that special machinery and equipment are required to manufacture the circuit boards, or the number of man-hours required to produce the circuit boards increases. That is, in order to fix the backing plate, expensive mechanical equipment such as a thermocompression bonding machine is required, and the number of steps required for adhesion is also increased, resulting in an increase in the number of processing steps.

SUMMARY OF THE INVENTION An object of the present invention is to provide a mounting method that solves the above drawbacks and achieves the initial objective of making an IC smaller and thinner without increasing equipment costs and man-hours.

The gist of the present invention to achieve the above object is to provide a recess for storing and positioning the backing plate in the carrier used in the mounting process, so that when the sealing resin hardens, the circuit board and the backing plate are By adhering the circuit board and the backing board, the process of adhering the circuit board and the backing board in advance can be eliminated.

Embodiments of the present invention will be described in detail below in the order of processing steps with reference to the drawings.

FIG. 1 shows a sectional view of an IC mounting part in a carrier commonly used in each process of the present invention.

Reference numeral 1 denotes a carrier, which is formed by processing steel material, aluminum material, heat-resistant resin material, etc., and has a recess 1a formed so as to accommodate a backing plate, which will be described later, with a slight gap.
and a plurality of bins 1b for positioning circuit boards to be described later. Note that the carrier 1 may be for a single circuit board or for continuously mounting a plurality of circuit boards.

FIGS. 2(a) to 2(e) are cross-sectional views showing the IC mounting part according to the present invention in the order of steps.

Figure 2 (a) shows a carrier 1, a backing plate 2 and a circuit board 3.
FIG. 3 is a cross-sectional view of the IC mounting section in a state where the IC mounting part is mounted. The backing plate 2 is a sheet made of metal or resin, and is housed in the recess 1a of the carrier 1 with a slight gap.

3 is a circuit board, which has a circuit pattern 6c on its upper surface, a penetrating device hole 6b for embedding an IC, and a plurality of positioning holes 6a. The pin 1b of the carrier 1 fits into the carrier 1, and the carrier 1 is mounted on the carrier 1.

FIG. 2(b) is a sectional view of the IC mounting part with the IC 4 bonded thereto. A thermosetting resin adhesive 5 is dropped into the device hole 6b of the circuit board 6 and on the surface of the backing plate 20, and then the IC 4 is mounted and bonded.

FIG. 2(e) is a sectional view of the IC mounting part in a state where wire bonding has been performed in the first step. The connection electrode provided on the surface of the IC 40 and the circuit pattern 6C provided on the circuit board 6 are connected by a bonding wire 6 made of an Au wire or an Al wire.

FIG. 2(d) is a sectional view of the IC mounting part in a state where the periphery of the IC 4 is sealed with the sealing resin 7. An appropriate amount of sealing resin 7 made of epoxy resin or the like is supplied onto and around the ICJ using a dispensing device, and the carrier 1 is then passed through a curing furnace to harden the sealing resin 7.

The supply amount of the sealing resin 7 is such that it fills at least the gap 8 between the device hole 6b of the circuit board B and the IC4, and further fills the gap 8 between the IC4 and the device hole 6b of the circuit board B.
and the bonding wire 6 are adjusted so as to completely cover them.

At this time, the sealing resin 7 fills the gap 8, reaches the backing plate 2 at the bottom of the gap 8, and also flows into the slight gap 9 between the circuit board 6 and the backing plate 2, so that When the sealing resin 7 hardens, the backing plate 2 and the circuit board 3 can be adhesively fixed at the same time.

FIG. 2(e) is a sectional view of the IC mounting portion with the circuit board 3 removed from the carrier 1 after the sealing resin 7 has hardened. The backing plate 2 has already been bonded to the circuit board 3, and this is the state in which the IC mounting is completed.

FIG. 3, FIG. 4, FIG. 5, and FIG. 6 are sectional views of an IC mounting portion showing other embodiments of the present invention.

In the explanation of FIG. 2(d) above, in order to further increase the adhesion between the backing plate 2 and the circuit board 3, a shallow dredge 6d was pre-machined on the back surface of the circuit board B as shown in FIG. Alternatively, as shown in FIG. The sealing resin 7 may easily flow into the sealing resin 7, or the backing plate 2 may be provided with through holes 2b as shown in FIG. Further, as shown in FIG. 5, the technique of using a frame 10 for preventing the sealing resin from flowing is well known and may be used in combination with any of the embodiments described above.

In addition, in the steps explained in FIGS. 2(b) and 2(C) above, in order to prevent the backing plate 2 from moving slightly in the recess 1a of the carrier, a hole is inserted through the carrier 1 as shown in FIG. The backing plate 2 may be fixed to the carrier 1 by suction by drilling a hole 1C and drawing a vacuum inside the through hole 1c.

The semiconductor element mounting structure constructed through the series of steps described above achieved performance equivalent to that of a conventional mounting structure in which a semiconductor element was mounted in a reliability test.

As mentioned above, by providing the recessed part in the carrier to accommodate the backing plate, it is possible to resin-seal with sealing resin in the gap for resin sealing and to bond the circuit board and the backing plate. , there is no need for the process of adhering the backing plate to the circuit board in advance, and no special equipment is required for manufacturing the circuit board.
In addition, in the entire mounting process including the manufacturing process of the circuit board, the number of processing steps can be reduced compared to conventional methods, and a thinner, smaller, and less expensive IC mounting method can be realized.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of a carrier used in the present invention. Second
Figures (a) to (e) show the IC mounting process in the present invention.
C sectional view of the mounting part. FIG. 3, FIG. 4, FIG. 5, and FIG. 6 are partial sectional views showing other embodiments of the present invention. 1...Carrier, 2...Backing board, 6
......Circuit board, 4...ICl3...
... Resin adhesive, 7... Sealing resin. Figure 1 Figure 2 (Q) (b) Figure 2 (d) (e)

Claims (1)

[Claims] In a mounting method in which a backing plate is fixed to the back side of a device hole provided in a circuit board, an IC is bonded to the backing plate, and the wire board/diag/g is sealed with resin, the carrier used in the mounting process is A recessed portion is provided to accommodate the backing plate, and resin sealing is performed with the device hole of the circuit board and the backing plate positioned and in contact with the carrier, so that when the sealing resin hardens, A method for mounting an IC, characterized in that the circuit board and the backing plate are fixed by adhesive.