JPS5824014B2 - Manufacturing method of mounting body - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a package, particularly an IC.

The present invention relates to a method of manufacturing a portion that connects an electrode terminal of an LSI element to an electrode terminal of an external circuit, and provides a method of forming a lead terminal with simple steps and low cost.

Several methods have been developed to electrically lead out electrode terminals formed on elements such as ICs and LSIs to electrode terminals of external circuits, but the most well-known method is 2.
There is a so-called wire bonding technique in which the electrode terminals are connected to each other by a thermocompression bonding method or an ultrasonic method using ultrafine wires of Au, AI, etc. having a diameter of 5 to 37 φμm.

In this method, the reliability of the connection is high when the number of electrode terminals is small, but as the number of functions in one element increases as in recent LSIs, the number of electrode terminals increases to 40 to 70 terminals. Two bondings are required for each terminal to make this connection.

That is, when the number of electrode terminals of an element is 70, the number of connections reaches 140, which is extremely large.

This lowers the reliability of the connection and makes it difficult to reduce the cost of this connection process.

Also, when connecting to external circuits, the above-mentioned IC, LSI
It is extremely difficult to realize a thinner and smaller package because the element must be fixed to the circuit board and the ultra-thin wire is lifted up in a curved manner.

In order to eliminate such drawbacks, a wireless technology that does not use so-called ultra-fine wires has been put into practical use, which connects, for example, 70 electrode terminals at once.

For example, in the beam lead method in this wireless technology, a rectangular electrode lead is formed on the electrode terminal of the element at the silicon wafer processing stage of the element.

However, in the beam lead method, elements cannot be formed on the silicon surface where electrode leads extending from electrode terminals are formed.

Therefore, the effective area in which elements are formed within one wafer is 55% compared to when elements are formed completely within the entire wafer.
0 to 60%, resulting in extremely poor wafer utilization efficiency.

That is, since the length of the lead is usually 0.7 to 1.2 mm, the silicon region around this length around one element exists solely for the purpose of forming the lead.

Therefore, not only are expensive silicon wafers used in vain, but the manufacturing process for forming electrode leads is complicated, which makes it more expensive and thinner and smaller.
Tanashi was the one who realized the cost reduction.

In addition, in the film carrier method, metal protrusions (usually called bumps) are placed on the electrode terminals of the device during the wafer process stage.
The connection is made by applying pressure and heating to the Sn-plated Cu foil lead formed on the polyimide film on the metal protrusion to form an Au-8n eutectic. Since the metal protrusion and the lead must be connected, the number of connection points is the same as the wire bonding method, which increases the number of steps, and uses expensive film, so although it is suitable for mass production, On the contrary, it became more expensive.

The present invention is based on consideration of such problems, and an electrode terminal for external connection is formed on the surface.

For example, the present invention provides a method that can solve the above problems by easily and accurately forming lead electrodes for external connection using a plating method on elements such as ICs and LSIs.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, an element 1 such as an IC2LSI is connected to a supporting substrate 2.
The element 1 is then divided at the top (FIG. 1a), and the element spacing is further increased (FIG. 1b).

To increase the spacing between the elements 1, you can cut the elements 1 with a dicing die or the like and then arrange them at equal intervals on another substrate, or place the diced elements on a resin sheet (product name: Millimex). , by heating and expanding,
The element spacing can be expanded freely.

Next, a first photosensitive resin 3 is applied to the entire surface, and holes as shown in 4 are made by photoetching only in the vicinity of the electrode terminal 1' of the element 1.

This state is shown in FIG. 1C, and it is necessary that the photosensitive resin 1 also covers a part of the main surface of the element 1.

Further, a recess is provided in the substrate 2, and the element 1 is buried in this recess.
If it is fixed, the film thickness of the first photosensitive resin 3 can be made thinner as a whole.

Next, a metal film 5 consisting of multiple layers is deposited on the entire surface (first
Figure d).

This metal film 5 consisting of multiple layers contains Cr-Cu, Cr
-Cu-Au, Cr-Ni, Cr-Ag
, Cr-Au, Tn-Cu, Tn-Au, etc. are used.

Here, the Cr and Tn films are materials that are in direct contact with the element surface to obtain adhesion strength with the element, and Cu.

Ag, Au, and Nu are materials for increasing conductivity.

A second photosensitive resin film 6 is applied on the metal film 5, and the element 1 is
An elongated rectangular region 1 is opened on the device plane, including the upper opening 4 (FIG. 1e).

Next, using the metal film 5 consisting of multiple layers as one of the plating electrodes, Au, Ag, Cu, or the like is plated on the rectangular region 7 to a thickness of 10 to 50 μm.

In FIG. 1e, rectangular regions 7 are formed in a separated state between the elements due to the presence of the pattern of the resin film 6, as shown in the figure.

Next, the second photosensitive resin 6 is removed, the exposed unplated metal film 5 is etched away, and the first photosensitive resin 3 is also removed to obtain the state shown in FIG. 1(f).

That is, it is possible to obtain an element in which the leads 8 are formed on the electrode terminals 1' of the element 1, parallel to the element surface and facing outward.

FIG. 2 is a perspective view of FIG. 1f.

To mount the element made in this way on a circuit body, the temperature of the board 2 is raised to soften the adhesive bonding the board 2 and the element 1, and the lead 8 is removed using vacuum tweezers or the like. The lead 8 and the pattern of the circuit body are aligned, and then the lead 8 and the pattern of the circuit body are bonded by thermocompression or eutectic/alloyed, thereby mounting can be carried out.

The above method provides the following effects.

■ As mentioned above, the film carrier method is highly suitable for mass production because the element chips are handled by tape transport, but it requires a bonding process (usually called ILB) to connect the electrode leads formed on the wafer. shall be.

This bonding process heats (400-500℃)
, the AI electrode terminal is deformed due to the pressure (30-60 g/pad) applied on the bump and the electrode of the device, and the AI
Cracks occur in the CVD5i02 film covering part of the electrode terminal.

Since the AI electrode terminal is exposed due to this crack, the corrosive solution of the AI electrode terminal enters from this part and dissolves the A1 electrode terminal, reducing the strength of the bump and increasing the contact resistance between the bumps. , which caused a decrease in reliability.

However, in forming electrode leads according to the manufacturing method of the present invention, the electrode leads are formed by a plating method (this is formed by the same method as the bump formation in the film carrier method). As shown in FIG. 2, there is no need for an ILB process, which is a bonding process, and no cracks occur in the CVDSiO2, so it is possible to reduce the number of man-hours and improve reliability.

Furthermore, in forming bumps on electrode terminals in the film carrier method, since the milling process is performed in the wafer state, bumps are formed on the electrode terminals of all chips, including defective chips.

For this reason, bumps formed on defective chips (e.g. Au
Bump) is completely useless.

However, in the present invention, only good chips can be selected in advance and electrode leads can be formed only on good chips.

Therefore, waste of materials can be eliminated and manufacturing costs can be reduced.

■ On the other hand, in the beam lead method, the wafer area must be occupied by the beam lead, so the yield of chips per wafer deteriorates significantly, and beam leads are also formed on defective chips. This wastes material and increases manufacturing costs.

In the manufacturing method of the present invention, since only the web can be sent separately and input into the manufacturing process, manufacturing costs can be reduced.

As described above, the present invention eliminates the drawbacks of the conventional beam lead and film carrier methods and provides a new manufacturing method for semiconductors having thinner and smaller lead terminals that are low cost and highly reliable. It is possible to obtain a packaged body of electronic circuit elements such as devices, which greatly contributes to high-density packaging.

[Brief explanation of the drawing]

FIG. 1a=f is a cross-sectional view of the manufacturing process of a mounting body according to an embodiment of the present invention, and FIG. 2 is a perspective view of the mounting body in the state shown in FIG. 1f. 1... Element, 1'... Electrode terminal, 2...
... Support substrate, 3.6 ... Photosensitive resin film, 4, 7 ... Opening region, 5 ... Metal film, 8 ... ...Lead.

Claims (1)

[Claims] 1. A step of installing the divided elements on a substrate at predetermined intervals, applying a first resin film on the substrate including the surface of the element, and forming an opening in the first resin film near the electrode terminal of the element. a step of depositing a metal film on the resin film and the opening; and a step of applying a second resin film on the metal film, and depositing a second resin film on the first resin film near the electrode terminal of the element. forming an opening in the second resin film that includes the opening and extends toward the peripheral edge of the terminal; and using the metal film as one plating electrode, the opening in the second resin film a step of forming a plating metal layer on the metal layer, and a step of removing the second resin film, using the plating metal layer as a mask, removing the exposed metal film, and further removing the first resin film. A method for manufacturing a mounted body, comprising: forming a lead terminal made of the plated metal layer in contact with an electrode terminal of the element.