JPH069784U - Compound solder - Google Patents

Abstract

(57) [Abstract] [Purpose] In a connecting material for electronic parts using solder, the thickness (height) of the connecting material can be kept constant during heating and melting so that peeling and conduction of semiconductor chips due to temperature changes (EN) Provided is a connection material extremely useful for manufacturing a semiconductor device, which is free from the risk of defects. [Structure] A solder layer 1 having a predetermined thickness is formed using a solder material such as PbSn or PbAgSn. A spacer member 2 made of a material (Cu, Ni, Mo, W, ceramics, alumina, glass, BN, etc.) having a melting point higher than that of the solder is embedded in the solder layer 1. The spacer member 2 has tangent lines 2a, 2a parallel to each other on the upper and lower surfaces thereof. When the solder is melted, the upper and lower tangents 2a, 2a are in contact with the two members to be connected, respectively, so that the thickness (height) of the solder layer 1 during melting is kept constant, and the thermal cycle after the connection is completed. Prevents the strength from decreasing.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a connecting material used for connecting electronic components in a power transistor and the like, and more particularly to improvement of solder used for fixing a semiconductor chip to a substrate.

[0002]

[Prior art]

 BACKGROUND ART Conventionally, as a material used for connecting a semiconductor chip to a substrate, a connecting material is known in which solder is molded into a tape (or ribbon) having a thickness of about 0.1 mm or a pellet. The connection material F is a material cut into chips and placed on the substrate C, and the semiconductor chip B is set on the connection material F and then heated and melted to fix the semiconductor chip B onto the substrate C. (See Figure 3).

[0003]

[Problems to be solved by the device]

 However, since the conventional connecting material F has a single-layer structure composed of only solder, its shape collapses during melting and the thickness (height) after solidification becomes uneven as shown in FIG. In some cases, the predetermined thermal cycle strength cannot be obtained in the thin portion, and there is a possibility that peeling of the semiconductor chip B or conduction failure may occur due to temperature change.

The present invention has been made in view of such conventional circumstances, and an object thereof is to, when connecting electronic components by using solder, when connecting the thickness of the connecting material during heating and melting. (Height) can be kept constant so that a predetermined heat cycle strength can be obtained after connection.

[0005]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the composite solder according to the present invention is a solder layer having a predetermined thickness, which has a spacer member formed by a material having a melting point higher than that of the solder and having parallel parallel upper and lower tangent lines. It is characterized by being put inside.

[0006]

[Action]

 According to the composite solder of the present invention, the solder layer and the spacer member are interposed between the two members to be connected, and when the solder melts, the tangent lines above and below the spacer member contact each member respectively. Since the members are supported in parallel with each other, the thickness (height) of the solder layer at the time of melting can be kept constant, and the thickness after solidification can be made uniform.

[0007]

【Example】

 Hereinafter, an embodiment of the composite solder of the present invention will be described with reference to the drawings, taking as an example a material used as a bonding material for fixing a semiconductor chip B onto a substrate C. The composite solder A shown in FIGS. 1 and 2 shows an example in which a thinner band-shaped spacer member 2 is embedded in a solder layer 1 formed in a thin band shape to produce a substantially tape shape (or ribbon shape). .

The solder layer 1 is made of a well-known solder material such as PbSn, PbAgSn or the like, and is formed in a thin band shape having a width slightly smaller than that of the semiconductor chip B and a thickness of about 0.1 mm. A strip-shaped spacer member 2 extending along the length direction of the solder layer 1 is embedded in the solder layer 1.

The spacer member 2 is made of a material having a melting point (at least 50 ° C. or higher) higher than that of the solder forming the solder layer 1, for example, Cu, Ni, Mo, W, ceramics, alumina, glass, BN, etc. It is formed into a thin strip that can be embedded in the solder layer 1.

The spacer member 2 has tangent lines 2a, 2a which are parallel to each other on the upper and lower surfaces thereof. These tangents 2a and 2a contact the semiconductor chip B and the substrate C when the solder is melted, thereby supporting the chip B and the substrate C in parallel with each other. It is preferable that the spacer member 2 has a metal film made of Ag, Au, Cu, Ni or the like formed on the surface thereof or is surface-treated with a flux to improve the familiarity with the solder.

The method of using the composite solder A of this embodiment will be described. First, the tip of the composite solder A produced in a tape shape as described above is a square piece (chip shape) that is one size smaller than the semiconductor chip B. It is cut into chips, mounted on a substrate C, and a semiconductor chip B is set on it (see FIG. 2 (a)).

When the chip-shaped composite solder A is heated in this state, the solder layer 1 is melted, and the upper and lower tangents 2a and 2a of the spacer member 2 are in contact with the semiconductor chip B and the substrate C, respectively. The chip B is supported in parallel with the substrate C, so that the thickness of the melted solder is kept uniform, and the thickness of the solidified solder layer 1'is kept constant (see FIG. 2 (b)). .

Therefore, in the state where the semiconductor chip B and the substrate C are connected to each other, a thin portion is not partially formed in the connecting portion, that is, the composite solder A ′ after solidification, and the predetermined portion is formed in the entire connecting portion. The thermal cycle strength of can be obtained. Therefore, it is possible to provide a highly reliable semiconductor device D in which there is no risk of peeling of the semiconductor chip B 1 or conduction failure due to temperature change.

The composite solder E shown in FIGS. 3 and 4 shows an embodiment in which a spacer member 3 having an X-shaped cross section is buried in place of the spacer member 2 having a rectangular cross section in the above-described embodiment.

The spacer member 3 of this embodiment is made of Cu, Ni, Mo, W, ceramics, alumina, glass, BN, etc., similarly to the spacer member 2 described above, and has a size that can be embedded in the solder layer 1. Then, it is manufactured in a long shape with an X-shaped cross section, and tangential lines 3b, 3b parallel to each other are formed between the left and right ends 3a, 3a on the upper and lower surfaces thereof. These tangent lines 3b and 3b contact the semiconductor chip B and the substrate C at the time of melting the semiconductor, thereby supporting the chip B and the substrate C in parallel with each other.

Also in this spacer member 3, a metal film of Ag, Au, Cu, Ni or the like may be formed on the surface or may be surface-treated with flux to improve the familiarity with solder. preferable.

The method of using the composite solder E of this embodiment will now be described. First, the tip portion of the composite solder E is cut into a rectangular piece (chip shape) that is slightly smaller than the semiconductor chip B, This is mounted on the substrate C and the semiconductor chip B is set on it (see FIG. 4 (a)).

When the chip-shaped composite solder E is heated in this state, the solder layer 1 is melted and the tangential lines 3b and 3b above and below the spacer member 3 are in contact with the semiconductor chip B and the substrate C, respectively. The chip B is supported in parallel with the substrate C, so that the thickness of the melted solder is kept uniform and the thickness of the solder layer 1'after solidification is kept constant (see FIG. 4 (b)). .

Therefore, similarly to the above-described embodiment, a thin portion is not partially formed in the solidified composite solder E ′, and a predetermined heat cycle strength can be obtained in the entire connection portion. Therefore, there is provided a highly reliable semiconductor device D in which there is no risk of peeling of the semiconductor chip B or defective conduction due to temperature change.

Regarding the cross-sectional shape of the spacer member, other than the above, a substantially W-shape, a substantially M-shape, an inverted concave shape, and the like are conceivable. In short, a cross-sectional shape capable of forming tangent lines parallel to each other in the upper and lower sides is possible. If there is no limitation.

Further, the composite solder of the present invention is not limited to the illustrated long one, and for example, it is used by making it into a sheet shape in which spacer members (2, 3) are arranged in parallel in the solder layer. At times, the external shape is arbitrary, such as cutting it into a chip of a predetermined size or preliminarily molding it into a chip.

Further, in each of the above embodiments, the bonding material for fixing the semiconductor chip B onto the substrate C has been described, but the present invention is not limited to this, and can be used for connecting various electronic parts. It goes without saying that the size and shape of the solder layer and the spacer member are appropriately changed according to the size of the two members to be connected.

[0023]

[Effect of device]

 Since the composite solder according to the present invention is configured as described above, the spacer member in the solder layer keeps the thickness (height) after melting the solder uniform, and the thermal cycle strength It can prevent the deterioration. Therefore, it is extremely useful for manufacturing a highly reliable semiconductor device in which there is no possibility of peeling of a semiconductor chip or defective conduction due to temperature change.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a composite solder according to the present invention, with a part cut away.

FIG. 2 is a cross-sectional view of a state in which a semiconductor chip is connected to a substrate by using the composite solder of the present invention, (a) before melting of solder, (b)
Indicates after the solder is melted.

FIG. 3 is a perspective view showing another embodiment of the composite solder according to the present invention, with a part cut away.

FIG. 4 is a cross-sectional view of a state in which a semiconductor chip is connected to a substrate using the composite solder according to FIG. 3, (a) shows before melting of the solder,
(b) shows after the solder is melted.

FIG. 5 is a cross-sectional view of a state in which a semiconductor chip is connected to a substrate using a conventional connecting material, in which a phantom line indicates before solder melting and a solid line indicates after melting.

[Explanation of symbols]

A, E: Composite solder 1: Solder layer 2,
3: Spacer members 2a, 3b: Tangent line B: Semiconductor chip C:
substrate

Claims (1)

[Scope of utility model registration request] 1. A composite solder, characterized in that spacer members having upper and lower parallel tangent lines and formed of a material having a melting point higher than that of solder are put in a solder layer having a predetermined thickness.