JPH0259399A - Semiconductor device for ic card - Google Patents

Abstract

PURPOSE:To alleviate residual stress in an IC chip and enhance yield of production by using a material having a Young's modulus of not more than a specified value as a die-bonding material for an IC chip of a semiconductor device comprising an IC module mounted on a card. CONSTITUTION:As a die-bonding material 11, a resin having a Young's modulus of not more than 100kgf/mm<2> is used, whereby a residual stress in an IC chip 10 upon fabrication of an IC module 3 is markedly alleviated. That is, when the die-bonding material having a low Young's modulus and being comparatively soft is used, the residual stress on the face side of the IC chip arising from heat shrinkage of the die-bonding material 11 is greatly reduced. Also, it is possible to enhance the breaking limit of the IC chip upon exertion of an external force on an IC card fabricated by use of the IC module.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a semiconductor device for an IC card, and more specifically, to a chip-on-board type IC for mounting on a card.
Regarding modules.

[Prior Art] IC cards are rapidly gaining popularity in recent years because they are compact, have a large storage capacity, and can read and write information.

Figures 6 to 10 relate to conventional IC cards, and as shown in Figures 6 and 7, an IC chip for an IC card is placed in a resin storage recess in a card 1 made of plastic such as vinyl chloride. A structure in which an IC module 3 sealed with is built-in and mounted on a tower and fixed with an adhesive 2, and a terminal portion 4 for external connection formed on the IC module 3 is exposed on the surface of the card 1 and the road surface. are taken. When the IC card is installed in the card reader/writer, the terminal section 4
Information is read and written through the .

FIG. 8 shows the IC module 3. As shown in FIG.

In the figure, reference numeral 5 denotes a module substrate, and a conductor pattern 6 for connecting an IC chip and a metal die pad 7 are formed on one surface of the substrate.

Furthermore, a terminal portion 4 connected to the conductive pattern 6 through a through hole 8 is formed on the other surface of the substrate 5.

Reference numeral 10 denotes an IC chip, which is die-bonded onto the die pad 7 by heating and curing a die-bonding material 11 made of a thermosetting epoxy resin with a relatively high Young's modulus. is A
It is electrically connected to the conductor pattern 6 by wire bonding through the U-wire 12. A sealing material 13 is made of, for example, a thermosetting epoxy resin, and is formed by botting or transfer molding to encapsulate and protect the IC chip 10.

FIG. 9 is a block diagram showing the manufacturing process of the IC module 3. As shown in the figure, first, in step S1, a one-oil IC chip 10 is fixed onto the die pad 7 of the substrate 5 using the die bonding material 11 made of an epoxy thermosetting resin. Next, in a wire bonding step S2, the IC chip 10 and the conductive pattern 6 of the substrate 5 are connected. Next, in step S3, the botting step,
After the IC chip 10 is sealed with the sealant 13 and cured, the sealant 13 is polished to a predetermined thickness in a polishing step S4 to complete the IC module 3.

In addition, when forming the said sealing material 13 by transfer molding, a process is complete|finished by forming the sealing material 13 to a predetermined thickness in the transfer molding process of process S5 after the said process S2.

[Problem to be Solved by the Invention] By the way, in the above-described conventional IC module 3 for an IC card, the die-bonding material 11 has a Young's modulus of 300.
A relatively hard (high Young's modulus) material of Kgf/mm2 or more is used, and after the die bonding process, the die bonding material 1
Due to the shrinkage stress of 1, the surface of the IC chip 10 has a first
As shown in Figure 0(a), a large tensile stress is generated. For example, when a thermosetting epoxy die-bonding material with a Young's modulus of 330 Kgf/mm 2 is used, a tensile stress of about (+) 85 MPa is generated, as shown by the symbol * in FIG. 4.

As shown in FIG. 10(b), the tensile stress on the surface of the IC chip 10 after this die bonding step is temporarily relieved to the compressive stress side by the contraction of the sealing material 13 during the next potting step. By the subsequent polishing process of the sealing material 13,
As shown in FIG. 10(c), tensile stress is generated again on the surface of the IC chip IO. That is, using the above die bonding material, the Young's modulus is 550 Kgf/mm as the sealing material 13.
When the thermosetting epoxy resin of No. 2 is used, the surface of the IC chip IO has (+) after the polishing process as shown in Figure 4.
) A tensile stress of over 50 MPa is generated.

Incidentally, the fracture limit value of the IC chip 10 is expressed by the tensile stress (
10) 100MPa, compressive stress (-)500MPa
Therefore, the tensile stress of the IC chip IO caused by the die bonding process described above can cause problems such as the occurrence of IC chip cracks during the assembly process, a decrease in the IC chip breakdown limit after being made into a card, and a decrease in the yield of wire bonding. There is a problem in that the manufacturing yield and the reliability of the product are significantly deteriorated.

In order to solve this problem, it may be possible to reduce the amount of polishing of the sealing material 13 to a very small amount, but the thickness of the IC card is specified to be 0.78 mm according to the standard, and the thickness of the IC module 3 is the maximum. It is restricted to 0.68 mm or less. Moreover, the thickness of the IC chip 10 is 0.3 mm, and considering the thickness of other elements, the thickness of the sealing material 13 is inevitably 0.3 mm.
．． The residual tensile stress on the surface side of the IC chip 10 was limited to about 18 mrn or less, and the residual tensile stress on the surface side of the IC chip 10 could not be alleviated.

Note that even when the encapsulant 13 is formed by a transfer molding method, the thickness of the encapsulant 13 is similarly restricted;
Similarly, tensile stress was generated on the surface side of the IC chip, and a similar interlayer was noted.

Therefore, the technical problem to be solved by the present invention is to solve the above-mentioned problems of the prior art, and its purpose is to reduce the residual stress of IC chips, thereby increasing the manufacturing yield. An object of the present invention is to provide a semiconductor device (IC module) for an IC card that can be improved and has high reliability.

[Means for Solving the Problems] The above-mentioned object of the present invention is to die-bond an IC chip onto a substrate, perform wire bonding between a conductive pattern on the substrate and the IC chip, and further seal the IC chip with a sealing material. In the semiconductor device for an IC card, the IC module is mounted on the card.
The die bonding material for C chip has a Young's modulus of 100Kgf/
This can be achieved by using a material with a diameter of 2 mm or less.

[Function] As a result of various studies, the inventors of the present application found that by using a resin with a Young's modulus of 100 Kgf/mm" or less as the die-bonding material, the residual stress of the IC chip after manufacturing the IC module can be significantly reduced. By using a relatively soft die-bonding material with a smaller Young's modulus than conventional ones, ICs generated due to thermal contraction of the die-bonding material can be reduced.
Residual stress on the chip surface side is significantly reduced. Furthermore, it was confirmed that the destruction limit value of the IC chip when an external force is applied to the IC card after being made into a card can also be improved.

[Example code] The present invention will be explained below with reference to illustrated embodiments.

FIG. 1 is a diagram showing an IC module which is a semiconductor device for an IC card according to a first embodiment of the present invention. In the figure, the same members as those in the conventional configuration shown in FIG. 8 are given the same reference numerals. The explanation will be omitted to avoid duplication.

The IC module 3A of the first embodiment has the same structure as the conventional example shown in FIG. 11A, a thermosetting silicone rubber resin (rubber paste) having a Young's modulus of 0.2 Kgf/mm2 is used.

The thickness of the die bonding material 11A is set to about 30 μm, and the IC chip 10 having a thickness of about 300 μm is fixed onto the substrate 5 via the die pad 7 by heating and curing the die bonding material 11A.

After the Au wire 12 is wire-bonded as described above, the sealing material 13 is filled by botting, and then polished to a predetermined thickness to complete the IC module 3A. In this example, this sealing material 1
3, a thermosetting epoxy resin with a Young's modulus of 550 Kgf/mm is used, and after polishing, the thickness of the sealing material 13 on the surface of the IC chip 10 is at most 18 kgf/mm.
It is set to be approximately 0 μm.

FIG. 2 is a diagram showing an IC module as a semiconductor device for an IC card according to a second embodiment of the present invention, and an IC module 3B in this embodiment is formed by transfer molding a sealing material.

The conductor pattern 6 and die pad 7 are formed on one surface of the substrate 5A shown in the same figure, and the substrate 5A is
A conductive pattern 6 is formed on the other surface through the through hole 8.
The terminal portion 4 connected to the terminal portion 4 is formed. and,
The IC chip 10 is made of die bonding material lI of the first embodiment.
Die bond material 11A with the same material, Young's modulus, and thickness as A
After die bonding, the IC chip 10 and the conductor pattern 6 are wire-bonded using the Au wire 12, and then a sealing material 13 of the same material and Young's modulus as the sealing material 13 of the first embodiment is used. ' by the transfer molding method, the IC module 3B is completed.

The thickness of the sealing material 13' on the surface of the IC chip 10 is set to the same thickness as in the first embodiment.

FIG. 4 shows the IC chip 1 of the first embodiment of the present invention described above.
0 surface residual stress and IC chip 10 in conventional configuration
The residual stress characteristic diagram is shown for each process (after die bonding, after sealing by botting, and after polishing) in comparison with the residual stress on the surface. The dotted line indicates the conventional example, and the conventional structure is the same as the first example except that the Young's modulus of the die bonding material 11 is 330 K g f / m m 2. Under the same conditions. Note that the (+) side of the residual stress value in the figure indicates tensile stress, and the (-) side indicates compressive stress, and the stress measurements were performed on the surface of the IC chip 10.

As is clear from the figure, in the first embodiment of the present invention, the residual stress is approximately (+)1 after die bonding.
4 MPa, and the residual stress after polishing (after completing the module) is approximately () 14 MPa, and the effect of reducing residual stress is remarkable compared to the conventional example.

Therefore, it has been confirmed that the manufacturing yield and product reliability can be significantly improved without causing damage to the IC chip 10 during the assembly process or lowering the destruction threshold of the IC chip 10 after it is made into a card. Ta.

In addition, the above-mentioned No. 1. In the second embodiment, the Young's modulus of the die-bonding material 11A is set to 0.2 Kgf/mm'', but according to experiments, although there is some variation, if the Young's modulus of the die-bonding material 11A is approximately 100 Kgf/m rn 2 or less. It was confirmed that the residual stress on the surface of the IC chip 10 after being made into an IC module can be reduced to about 1/3 or less in absolute value compared to the conventional one, and the Young's modulus can be reduced to 100 kgf/
If rnm2 is used, it will greatly contribute to improving yield and reliability in actual use. Furthermore, in order to reduce the residual stress of the IC chip 10 as much as possible, there is a need to balance the Young's modulus of the sealing material, and the Young's modulus of the die bonding material 11A is 50 K.
It is desirable to set it to K f /mm'' or less.

FIG. 5 is a load-stress characteristic diagram showing the relationship between the applied load and the stress on the surface of the IC chip 10 after it is made into an IC module, and the characteristic line A in the figure shows the Young's modulus of the die bonding material of 0.2.
Kgf/mm", characteristic line B in the same figure represents the case where the Young's modulus of the die-bonding material is 20 Kgf/mrn2, and characteristic line C in the same figure represents the Young's modulus of the die-bonding material at 100 K.
The experimental examples of the present invention when Hf /+nm2 are shown, and the characteristic line in the same figure shows that the Young's modulus of the die bonding material is 330.
Kgf/m m'' (conventional example), and the Young's modulus of the sealing material is 550 Kgf/rnm2 in both cases.
It's Toshide. The measurement method is L=12 as shown in Figure 3.
rnm, W=l Ornm's IC module 3 (3A or 3B) is supported by two bar-shaped supports 14, and a three-point bending test is performed in which a load F is applied to the opposite surface, and the surface stress of the IC chip 10 is measured. did.

As is clear from Fig. 5, if the Young's modulus of the die-bonding material is 100 Kgf/mm2 or less, even if an external force of over 2 Kgf is applied, only a stress of (+)100 MPa or less will be generated in the IC chip, which is not practical. It has been confirmed that the IC chip is not damaged even if the IC card is handled fairly roughly.

In addition, the above-mentioned 1. In the second embodiment, silicone rubber is used as the die bonding material, but it goes without saying that any other material such as epoxy resin or acrylic resin may be selected. Furthermore, various materials can be selected for the sealing material; for example, a photo-curable acrylic resin is potted, and this is pressed with a glass plate and irradiated with light while controlling the knob shape. The resin may be cured and sealed.

[Effects of the Invention] As described above, according to the present invention, the residual stress of the IC chip can be reduced, the FFD manufacturing yield can be improved, and a highly reliable semiconductor device (IC module) for an IC card can be provided. , its industrial value is enormous.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an IC module according to a first embodiment of the present invention, FIG. 2 is a sectional view of an IC module according to a second embodiment of the present invention, and FIG. 3 is an explanatory diagram of a three-point bending test. Figure 4 shows ICs for each manufacturing process of the first embodiment of the present invention and the conventional example.
A residual stress characteristic diagram showing the residual stress of the chip. Figure 5 is a load diagram showing the relationship between the applied load and the stress of the IC chip in each IC module with different Young's modulus of the die-bonding material.
Stress characteristic diagrams, Figures 6 to 10 relate to conventional examples, Figure 6 is a plan view of the IC card, Figure 7 is a sectional view of the main parts of the IC card, Figure 8 is a sectional view of the IC module, and Figure 8 is a sectional view of the IC module. Figure 9 is a block diagram showing the manufacturing process of the IC module, and Figure 10 is the IC module.
FIG. 3 is a modeled explanatory diagram for explaining the generation of residual stress in a chip. l...Card, 2...Adhesive, 3.3
A, 3B...IC module, 4...
Terminal part, 5,5A... Board for module, 6
...Conductor pattern, 7...Die pad, 8...Through hole, 10...IC
Chip, 11. IIA・・・Die bond material, 12
...Au wire, 13.13'... Sealing material. Figure 5Figure 4

Claims (1)

[Claims] Along with die bonding the IC chip onto the substrate,
In a semiconductor device for an IC card, in which an IC module is mounted on a card by wire bonding a conductor pattern on a substrate and an IC chip, and further sealing the IC chip with a sealing material, A semiconductor device for an IC card, characterized in that the die-bonding material is a material having a Young's modulus of 100 Kgf/mm^2 or less.