JPH04168749A - Semiconductor package - Google Patents

Abstract

PURPOSE:To realize accurate positioning of I/O pins only through connection of a positioning member with a connecting pad by bonding the positioning member to an IC chip in predetermined positional relation with respect to the I/O pins. CONSTITUTION:A semiconductor package comprises a heat spreader 2 having leg parts at four corners and an IC chip 3 bonded to the heat spreader 2. The IC chip 3 is previously provided with a multiplicity of electrodes 5 bonded with a plurality of I/O pins, i.e. micro pins 6, in grid. When (a) and (b) are aligned reliably and a circuit is arranged in same positional relationship on the side of the printed board at the time of bonding of the IC chip 3 and the heat spreader 2, all micro pins can be aligned by simply mounting the IC chip 3 with each leg part being aligned.

Description

Detailed Description of the Invention Technical Field The present invention relates to a conductor package, particularly for high power ICs.
This invention relates to a 7-conductor package that includes a chip and is used for fine pitch surface mounting.

Prior Art Conventionally, some semiconductor packages of this type are integrated with a heat sink.

For example, the third image shows the mounting state of a conventional semiconductor package.
Referring to the figure, ICl3 having multiple boards]2
is attached to the heat sink 14. The legs 15 of the heat sink 14 are connected to the conductor circuit 11 on the printed circuit board 9 by soldering or the like, and the leads 12 are connected to the conductor circuit (
It is connected to the connection pad (connection pad) 10 by soldering, thermocompression bonding, or the like.

When mounting such a conventional semiconductor package on the printed circuit board 9, a process is adopted in which the legs 15 of the heat sink 14 are first connected to the conductor circuit 11, and then each lead 12 is connected to the corresponding conductor circuit 10. It is being

That is, the purpose of the heat sink 14 in the conventional semiconductor package described above is to efficiently dissipate the heat of the ICl3, and no special measures are taken to align the IC leads 12 and the conductive circuit 10 on the substrate. do not have. This is because the lead 12 has a certain degree of freedom and can be easily aligned with the conductor circuit 10. Another reason is that the pitch of each lead is relatively large, and so strict alignment is not required.

However, in semiconductor packages, as the number of connection terminals increases, it is necessary to miniaturize the leads 12.
In conventional semiconductor packages, the lead pitch is 100 [
μm] or less, it becomes difficult to form leads. At the same time, when attaching the legs 15 and connecting the leads 12,
The drawback is that heat can cause deformation of the leads and misalignment with respect to the conductor circuit.

Further, the heat sink 7 of the conventional semiconductor package is L
Because it is fixed to SI, the material has a thermal expansion coefficient of L.
Must match S I material.

Further, since it serves as a heat sink, it is desirable that it has good thermal conductivity, and since it is necessary to form it into a fin shape, it is preferably made of a material that is easy to work with, and of course, it is preferably a material that is inexpensive. However, there are few materials that satisfy all of these conditions, and they also have the disadvantage of sacrificing some of the properties.

OBJECTS OF THE INVENTION The present invention has been made to solve the above-mentioned conventional drawbacks, and its eleventh objective is to provide a semiconductor package that can be easily mounted even if it is minute and has many terminals. It is.

Structure of the Invention A semiconductor package according to the present invention has an IC chip having a plurality of input/output pins on the back surface, and legs for positioning,
A positioning member is attached to and removed from the surface of the IC chip in a predetermined positional relationship, and the leg is connected to a positioning pad provided in advance on a printed circuit board. It is characterized by

Example Next, the present invention will be explained with reference to the drawings.

FIG. 1(a) is a perspective view showing the appearance of the back side of an embodiment of a semiconductor package according to the present invention, and FIG. 1(b) is a
FIG. 3 is a side view showing the appearance when the surface thereof is facing up.

In FIG. 1(a), a semiconductor package according to an embodiment of the present invention includes a heat spreader 2 with leg portions 1 provided at four corners, and an I.
It is composed of a C chip 3. A large number of electrodes 5 are provided in advance on the IC chip 3, and a plurality of micro pins 6, which are human output pins, are bonded to the electrodes 5 in a grid pattern.

In addition, as shown in the same figure (b), each electrode 5 and the micro pin 6 are, for example, A u / S n (80/
20wt%), etc., and the heat spreader 2 and IC chip 3 are
It may be attached using a bonding material 4 such as n/Ag (H, 5/3.5 wt%).

Furthermore, the length of the leg portion is increased by h compared to the length of the IC chip 3 and the micro pin 6 when they are combined.

This h takes into consideration the variation in the length of the micro pin 6,
In order to prevent connection failures during mounting on a printed circuit board, the thickness may be set to several hundreds [μm], for example. Note that the bottom surface of each leg may be square.

Furthermore, referring to FIG. 1(a), among the micro pins provided in the shape of a square, the dimensions of the micro pins provided at the four corners from each leg of the heat spreader 2 are a. , b, the IC chip 3 is attached to the bonding material 4.
is fixed. This dimension adjustment may be carried out using a microscope or the like. In other words, when bonding the IC chip 3 and the heat spreader 2 that make up this semiconductor package, ensure that they are aligned as shown in a and b above, and also conductors with the same positional relationship on the printed circuit board side. Once the circuits are placed, all the micropins can be reliably aligned by simply aligning each leg and mounting it. Note that the larger the conductor circuit is, the easier it is to perform alignment, but if it is too large, short circuits between adjacent circuits are likely to occur, so the size may be set appropriately depending on the number of input/output pins.

The mounting state will be explained using FIG. 2.

2 is a side view showing an example of mounting the semiconductor package of FIG. 1. FIG.

In the figure, the leg 1 is a conductor circuit on a printed circuit board 9 ] 1
At the same time, the micro pin 6 is connected to the conductor circuit 8 on the printed circuit board 9 at '-1'=m16.

In this case, 'Ii III is, for example, S
n/Pb (63/37wt%) may be used. Note that, as mentioned above, this l' III example is sometimes
The length of the leg portion 1 is longer by the IJ dimension than the length of the mating between the IC chip 3 and the micro pin 6.

Furthermore, by making the positional dimensions of the conductive circuit 11 and the conductive circuit 8 the same as the above-mentioned dimensions a and b in advance, the leg portion 1 can be mounted in alignment with the conductive circuit 11 on the printed circuit board 9. , the conductor circuit 8 and the micro pin 6 can be aligned.

In such a chip mounting structure, conventionally the electrodes on the IC and the conductor circuit on the printed circuit board are aligned based on, for example, the outer shape of the IC chip. However, the outer shape of the back surface of the IC chip is likely to be damaged during cutting, making accurate alignment difficult. In contrast,
In the present invention, by accurately aligning the positional relationship between the micro pins on the IC chip and the legs of the heat spreader, that is, the above-mentioned dimensions a and b, in advance, each leg of the heat spreader that acts as a positioning member and the conductor circuit are arranged. 1]
By aligning the printed circuit board with the IC electrode, the printed circuit board and the IC electrode can be automatically aligned.

In addition, the heat spreader 2 spreads and transmits the heat generated from the IC chip 3 to the back surface, and transfers the heat to the back surface of the IC chip 3.
It is cooled by a heat sink (not shown) that can be used for cooling. In addition,
The material of the heat spreader is Cu/W composite material, Af
IN, SiC, etc. have good thermal conductivity, and the thermal expansion coefficient is LSI
A material suitable for the material (silicon in this example) is used. This allows A, l? It is possible to use materials that are inexpensive and have good workability, such as copper or copper.

Furthermore, in addition to an air-cooled heat sink, it is also possible to cool by pressing a liquid-cooled type cold plate or the like, or by immersing it in an insulating liquid. Also, IC
Micro pins can relieve stress due to the difference in thermal expansion between the substrate and the substrate.

DETAILED DESCRIPTION OF THE INVENTION As described above, the present invention provides mounting on a printed circuit board by bonding a positioning member to an IC chip in a predetermined positional relationship with respect to input/output bins provided on the IC chip. In this case, the input/output pins can be easily and accurately aligned simply by connecting the positioning member to the connection pad.

[Brief explanation of drawings]

FIG. 1(a) is a perspective view showing the appearance of the back side of the ``1'' conductor package according to the embodiment of the present invention, and FIG.
) is a side view showing the external appearance when the surface of the semiconductor package is facing up, FIG.
Is the diagram conventional? (It is a perspective view showing the external appearance of the conductor package. Explanation of symbols of main parts 1...Legs 2...Heat spreader 3...IC chip 6... ...Micro pin 8.11...Conductor circuit

Claims (1)

[Claims] (1) An IC chip with multiple input/output pins on the back side,
It has positioning legs and includes a positioning member attached to the surface of the IC chip by adhesion in a predetermined positional relationship, and the legs are attached to positioning pads provided in advance on a printed circuit board. A semiconductor package characterized by being connected.