JPH04234157A - High-density memory package - Google Patents

Abstract

PURPOSE: To provide an ultra-compact electronic package that is suited for a high memory capacity and a high memory density, and to use a double-sided surface-mount technology assembly additionally. CONSTITUTION: A package 1 contains a plurality of IC memory chips 11 that are adhered to a circuited flexible tape substrate 21, and the circuited flexible tape substrate 21 is adhered to a printed circuit board 31 later. The circuited flexible tape substrate 21 is extended outward from the printed circuit board 31 and has a plurality of IC memory chips 11 mounted to an I/O pad on it. Each IC memory chip 11 is in contact with a heat sink means 41 on a surface that is opposite to the flexible tape substrate 21. The flexible tape substrate 21 and the heat sink means 41 are joined to the printed circuit board 31.

Description

[Detailed description of the invention]

0001

TECHNICAL FIELD This invention relates to microelectronic circuit packages and, more particularly, to multichip memory packages. The circuit package features efficient utilization of input/output circuitry, high memory density, and efficient thermal management.

0002

BACKGROUND OF THE INVENTION The general structure and manufacturing process of electronic packages are described, for example, by Donald P. Serafin.
ald P. Principles of Electronic Packaging (Principles of Electronic Packaging) by Seraphim, Ronald Lasky, and Che-Yo Li.
Rinciples of Electronic Pa
McGraw-Hill Book Company
), New York, NY (1988), and Rao R. Tummal.
a) and Eugene J. Rimacewski
J. Rymaszewski's Microelectronic Packaging Handbook (Microelectron Packaging Handbook)
ic Packaging Handbook)” Van Nostrand Reinhold (Van Nost
Rand Reinhold), New York, NY (1988).

As stated by Serafin et al. and Tumara et al., electronic circuits consist of a large number of independent electronic circuit components,
For example, it may contain thousands or even millions of individual resistors, capacitors, inductors, diodes, and transistors. These independent circuit components are interconnected to form circuits, and individual circuits are interconnected to form functional devices. Power and signal distribution takes place through these interconnections. Individual functional devices require mechanical support and structural protection. Electrical circuits require electrical energy to perform their function and the removal of thermal energy to maintain their function. Microelectronic packages such as chips, modules, connectors, cables, circuit cards, and circuit boards are used to protect, house, cool, and interconnect circuit components and circuits.

Within integrated circuits, interconnections between circuit components and between circuits, heat dissipation, and mechanical protection are provided by integrated circuit chips. This chip encapsulated within the module is called a first level package.

There is at least one more level of packaging. The second level package is a circuit card. Circuit cards serve at least four functions. First, circuit cards are used because the total number of circuits or bit counts required to perform the desired function exceed the bit count of the first level package or chip. Second, the second level package or circuit card provides space for components that cannot be easily integrated into the first level package or chip or module. These components include, for example, capacitors, precision resistors, inductors, electromechanical switches, optical couplers, and the like. Third, circuit cards provide signal interconnections to other circuit elements. Fourth, the second level package provides thermal management or heat dissipation.

[0006] For most applications, especially high performance workstations, midsize computers, and main frame computers, there is a third level package. This is a circuit board level package. Circuit boards contain connectors to accept multiple cards, circuitry to provide communication between cards, input/output devices to communicate with the outside world, and often include complex thermal management systems.

With modern application programs, complex operating systems, and multitasking,
Large amounts of random access memory are now available. This continually increases memory size and memory density. Increases in memory density are accompanied by increases in circuit density, wiring density, and input/output density, all of which impose higher thermal loads on electronic packages.

``Thermal Management in Electronic Packages'' on page 127 of ``Principles of Electronic Packages'' by Serafin, Lasky and Lee, incorporated herein by reference.
Electronic Packaging), F.E. Andros and B.G.
Sammakia notes that to improve the performance of data processing equipment, trends in electronic package design include larger circuit chip sizes and higher input/output densities per chip. However, the aim is to increase the circuit density per chip and improve the reliability of the system. These increases in chip size, input/output density, circuit density, and reliability have resulted in performance improvements, particularly by reducing electrical line length and point-to-point flight time. At the same time, these improvements have also resulted in significant increases in power density. For example, Antonetti, Oktay in "Electronic Packages" on page 167 of the Microelectronic Packaging Handbook by Tsumara and Limaszewski, which is hereby incorporated by reference. ) and Simons report that a 5 mm x 5 mm chip dissipates 10 watts for a heat flux of 400 kilowatts per square meter.

Despite the rapid decrease in the power demands of individual devices, there has been a very rapid increase in chip and package level thermal loads. This is because device density and integration are becoming more rapid. When solid state devices were first introduced, solid
It was believed that the lower individual power requirements of state devices compared to vacuum tube or iron core memory would minimize, if not eliminate, thermal management problems. In reality, this has not been the case, as the packing density of integrated circuits and the associated power density have increased rapidly over the years. For example, CMOS devices have lower power demands per device than bipolar devices, but the number of CMOS devices per modern CMOS integrated circuit is many times the number of bipolar devices per older bipolar integrated circuit. ing.

[0010] It should be noted that packaging design, ie, card and substrate design, has to meet the ever-increasing density of the aforementioned logic circuits and memories in smaller areas, and the concomitant increase in interconnections. has been promoted by As Andros and Samakia note, these high density cards and boards have high power densities and therefore require complex thermal management.

Package level thermal management is particularly important because the failure rate of integrated circuits increases by a factor of two for every 10° C. increase in operating temperature. Andros and Samakia point out that reliability at all levels of the package is directly proportional to temperature. For example, high operating temperatures accelerate failure mechanisms such as creep, corrosion, interdiffusion, and electromigration. Similarly, Andros and Samakia point out that temperature differences occurring as a system cycle between powered-on and powered-off states and are primarily responsible for fatigue in composite structures made of materials with different coefficients of thermal expansion. This has a significant impact on the reliability of electronic components.

Antonetti, Oktai, and Simons state that it is a requirement for thermal management of electronic packages to meet some or all of the following performance criteria:

*Integrated circuit device temperature
Operating conditions (ie, worst-case values of device and module power and thermal resistance, coolant flow rates, environmental conditions, etc.) must be maintained below maximum allowable limits.

*The temperatures experienced by integrated circuit devices under normal operating conditions must be such that reliability goals can be achieved.

*The temperature fluctuations of devices belonging to the same signal network must be kept within acceptable limits.

*The reliability of the thermal management method must be acceptable.

*Electronic noise limits must be met.

The objective of any thermal management design is to achieve thermal energy flow by allowing the flow of thermal energy from the heat source, ie, the integrated circuit memory chip, to the heat sink, ie, the external environment, within specified temperature and heat flux constraints. , is to achieve this purpose. Ideally, this would be achieved by a combination of conduction and natural or forced convection, or both.

The goal of memory packages is to combine efficient thermal management with high memory capacity and memory density.

[0020]

[Problem to be Solved by the Invention] The main purpose of the present invention is to
It is an object of the present invention to provide a microelectronic package that is compatible with high memory capacities and densities, and concomitantly allows the use of, for example, double-sided surface mount technology (SMT) assemblies.

Another object of the present invention is to provide a microelectronic package with high input/output capacity, including high address bus capacity and high data bus capacity.

Yet another object of the present invention is to provide a microelectronic package having thermal management capacity that matches the memory capacity and input/output capacity contemplated by the present invention.

Still another object of the present invention is to provide a circuitized flexible tape carrier for memory having individually bonded, assembled and tested memory chips, The goal is to eliminate the rework.

Yet another object of the invention is to reduce the package area occupied by common control and data lines and discrete devices.

[0025]

SUMMARY OF THE INVENTION A high density microelectronic circuit package is disclosed. The circuit package includes a plurality of IC memory chips that are bonded to a circuitized flexible tape and then bonded to a printed circuit board. The circuitized flexible tape extends outwardly from the printed circuit board and has a plurality of IC chips, such as memory chips, mounted on input/output pads.

The input/output pads on the circuitized flexible tape are arranged into at least first and second groups. A first group of input/output pads is connected to a common bus of the first connector. This first common bus terminates in an array of input and output contact pins on the edges of the flexible tape.

The second group of I/O pads is connected to a second group of connectors extending outwardly from the I/O chip toward the I/O contact pin array. An array of circuitized flexible tape input/output contact pins is aligned with and adhered to an array of contact pads on a printed circuit board.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A high density microelectronic circuit package 1 as described herein. Circuit package 1 includes a plurality of IC memory chips 11 adhered to a circuitized flexible tape substrate 21 and thermally bonded to a heat sink 41 . Circuitized flexible tape 21 and heat
Sink 41 is then glued to printed circuit board 31. Circuitized flexible tape 21 and heat sink 4
1 extends generally outwardly from the printed circuit board 31. A plurality of IC chips 11, such as memory chips, are attached to the input/output pads. The memory chips 11 may be arranged in a single row on the circuitized flexible tape 21 or in multiple rows (for example, 11a and 11b in FIGS. 4 and 5). ).

Circuitized flexible tape 21 includes a first input/output contact pad array. This first input/output contact pad array is the input/output contact (first
) can accept and be glued to an input/output terminal array on the surface. Although we are talking about a single contact array,
It may be a multiple contact pad array for data 3i/3o, address input/output, and control. Circuitized flexible tape 21 also includes a second input/output contact pad array. A second input/output contact pad array can receive and be adhered to an array of input/output pads 34 on printed circuit board 31.

The input/output pads of the circuitized flexible tape 21 can be arranged in a plurality of arrays, eg, at least a first group 22a and a second group 22b. The first group of input/output pads 22a are connected to a first conducting common bus 23a. This first common bus 23a
terminates in an array of input/output contact pads 24a at the edges of flexible tape 21. This first contact pad array 2
4a is then adhered to a matched first contact pad array 34 on printed circuit board 31.

The second group of input/output pads 22b are
The second conductor is connected to the common bus 23b of the conductor.
Extending outwardly from the C-chip to a second input/output contact pad array 24b on the edge of the circuitized flexible tape 21. A second input/output contact pad array 24b of circuitized flexible tape 21 is aligned with and adhered to a second array of contact pads 34 on printed circuit board 31. Contact pad arrays 24a and 24b may be at right angle edges of circuitized flexible tape 21.

Another embodiment shown in FIG. 4 provides higher input/output density. In this embodiment, circuitized flexible tape 21 includes a first input/output contact pad array 22a (not shown) on one surface thereof. This first input/output contact pad array 22a is capable of receiving and is adhered to the input/output terminal array of the input/output contact (first) side 15 of the IC chip 11. Circuitized flexible tape 21 may include a second input/output contact pad array on its back side. This second input/output contact pad array is connected to the first input/output contact pad array 22a by vias. A second input/output contact pad array can receive and be connected to an array of input/output pads on printed circuit board 31. In this way, separate buses are provided for data lines and address lines.

Thermal management is provided by a heat sink structure 41, which is mechanically and structurally separate from the circuitized flexible tape 21, but which is isolated from the individual IC chips. 11 is heat transfer bonded. Specifically, the heat sink means 41 extends generally perpendicularly outwardly from the printed circuit board 31 and extends outwardly from the printed circuit board 31 so that the IC chip 1
1 each have an input/output contact first surface 15 and a thermal contact second surface 17.
have. The IC chip 11 is adhered to the circuitized flexible tape 21 via the input/output contact (first) side 15 and to the heat sink means 41 via the IC chip thermal contact (second) side 17. has been done.

This structure is generally shown in FIGS. 1, 4 and 5. As mentioned above, the microelectronic package 1 of the present invention extends generally perpendicularly outward from the printed circuit board 31 and includes an input/output pad array 24 on the flexible tape 21 and an input/output pad array 24 on the printed circuit board 31. It is electrically connected to printed circuit board 31 via an input/output pad array 34 . An important aspect of the invention is the heat sink 41
This is the connection of the IC chip 11 to the IC chip 11. Microelectronic package 1 is thermally connected to printed circuit board 31 via heat transfer (second) surface 17 of IC chip 11 . These IC chip heat transfer surfaces 17 are coupled to heat sink means to enable heat transfer therebetween.

Individual IC chips 11 can be connected to heat sink 41 using a variety of methods. These include soldering, thermal grease, thermal paste, etc., but these are illustrative only and not limiting. Thermal greases and pastes include (1) a liquid polymer thixotropic suspension of a heat transfer agent; and (2)
Oils such as silicone oils (eg, diphenylene siloxane or dimethylene siloxane) or hydrocarbon oils are included mixed with small amounts of thixotropic solids (such as fugitive silica, clays, and soaps). Thermal greases and pastes act as flexible thermal conductors, ensuring that thermal conduction paths are maintained at the extremes of thermal expansion and contraction.

The IC chip 11 and circuitized flexible tape 21 may extend along a single side or surface of the heat sink means 41, as shown in FIGS. As shown in FIGS. 4 and 5, it may extend along both sides of the heat sink means 41. Therefore, in the embodiment shown in FIGS. 4 and 5, each of the IC chips receives heat via the heat transfer (second) surface 17 of the IC chip 11.
It is glued to the sink means 41. at least one I
A C chip 11 is glued to one surface of the heat sink means 41 and at least one other IC chip 11 is glued to the opposite surface of the heat sink means 41. In this configuration, the IC chips 11 are placed back to back.

When the IC chips 11 are bonded to the heat sink means 41 in a back-to-back configuration as shown in FIGS. 4 and 5, they can be combined into a single circuitized flexible It can also be attached to a flexible tape 21 or a plurality of circuitized flexible tapes 21 as shown in FIG.
(21a, 21b) can also be attached.

FIG. 4 shows the individual IC chips 11 (11a, 1
1b) and a printed circuit board 31 are electrically connected to each other via a single circuitized flexible tape 21. This single tape 21 surrounds the heat sink means 41 and the IC chip 11.

FIG. 5 shows the individual IC chips 11 (11a, 1
1b) and a printed circuit board 31 are shown electrically connected to each other via a pair of circuitized flexible tapes 21a, 21b. These plurality of tapes 21a, 21b are arranged on both sides of the heat sink means 41, and therefore the heat sink means 41
and surrounds the IC chip 11 (11a, 11b). In this embodiment, each IC chip 11 (11a
, 11b) and the printed circuit board 31 are electrically connected to each other via a pair of circuitized flexible tapes 21a, 21b. One circuitized flexible tape 21
a is adhered to the IC chip 11b on one side of the heat sink means 41, and the other circuitized flexible tape 21b is attached to the IC chip 11b on the opposite side of the heat sink means 41.
It is bonded to the C chip 11a.

Still another embodiment of the present invention is shown in FIG. In this embodiment, the memory IC chip 11, the circuitized flexible tape 21, and the heat sink 41 are a module unit, and the circuitized flexible tape 21 connects the IC chip 11 and the heat sink. The heat sink means 41 is wrapped around the base of the heat sink means 41 so that the heat sink means 41 is connected to the printed circuit board 31 through the opening in the circuitized flexible tape 21. . This module unit is, for example,
Batch soldering onto the printed circuit board 31 can be achieved by vapor phase soldering of the contact pads 24 on the flexible tape 21 and the contact pads 34 on the printed circuit board 31. In the embodiment shown in FIG. 6, the heat sink means 41 is finned.

Although the structure has been illustrated and described with respect to various mounting techniques, it should be understood that various direct chip attach (DCA) methods can be used to adhere IC chip 11 to circuitized flexible tape 21. . Typically, individual chips 11 are bonded to patterned metal on a tape (such as copper or polyimide), for example by thermocompression bonding, and this structure is then bonded to a flexible circuitized tape 21. , for example, tape automated bonding (TAB) bonded by external lead bonding. One of the advantages of DCA using TAB is that intermediate processing such as testing, encapsulation, and burn-in can be
This can be done before adhering the AB assembly to the circuitized flexible tape 21. Other DCA and thin film chip connection methods may be utilized without departing from the inventive concept.

The apparatus and structure of the present invention provides a high memory capacity and density microelectronic package with minimal area occupied by common control and data lines and discrete devices. Concomitantly, the package of the present invention allows double-sided surface mount technology (SMT) assembly. The disclosed microelectronic package has high input/output capacity, including high address bus capacity and high data bus capacity with thermal management capacity compatible with the disclosed memory capacity and input/output capacity. Digital I
Although described in terms of C-chips, it is noted that passive components such as resistors, capacitors, and inductors are present in the microelectronic package 1 as well as in analog IC chips.

As described herein, microelectronic package 1 includes a circuitized flexible tape carrier 21 for memory chips, to which memory chips 11 are individually adhered. , assembled and tested, which avoids multiple chip rework.

[0044]

The present invention provides a microelectronic package that is compatible with high memory capacities and densities, and may concomitantly enable the use of, for example, double-sided surface mount technology (SMT) assemblies.

[Brief explanation of the drawing]

FIG. 1 is an isometric view of a printed circuit board having a plurality of outwardly extending microelectronic packages.

FIG. 2 is a diagram of a microelectronic package of the present invention including a flexible strip substrate with two aspects of circuitry: data circuitry and address circuitry.

FIG. 3 is a diagram of an area of a microelectronic package where an IC chip is mounted on a flexible strip substrate and from which first and second leads extend.

FIG. 4 is an illustration of an embodiment of the invention in which a piece of flexible circuitized tape is wrapped around a heat sink.

FIG. 5 is an illustration of another embodiment of the invention having a pair of flexible circuitized substrates, one on each side of the heat sink.

FIG. 6 is yet another implementation of the invention in which the memory IC chip, circuitized flexible tape, and heat sink are modular units that can be batch soldered to a printed circuit board, for example by vapor phase soldering. FIG. 2 is an example diagram.

[Explanation of symbols]

1 High-density microelectronic circuit package 11 IC memory chip 21 Flexible tape substrate 22a, 22b First input/output contact pad array 24
, 24a, 24b Second input/output contact pad array 3
1 Printed circuit board 34 Input/output pad 41 Heat sink

Claims (21)

[Claims] Claim 1: (a) Each IC chip has a first input/output contact.
(b) a printed circuit board; (c) a plurality of IC chips extending outwardly from the printed circuit board and having first and second input/output surfaces thereon; a circuitized flexible circuit having a pad, an IC chip attached to a first input/output pad, and a second input/output pad aligned with and adhered to an array of contact pads on a printed circuit board; (d) heat sink means extending outwardly from the printed circuit board, the IC chip being adhered to the circuitized flexible tape by the input/output contact first side thereof; a high density microelectronic circuit package comprising a heat sink means adhered to the heat sink means by a second side of the thermal contact. 2. (a) an IC chip is bonded to a heat sink means on a second heat transfer surface thereof, at least one IC chip is bonded to one side of the heat sink means and at least one other is bonded to the heat sink means; an IC chip is adhered to the other side of the heat sink means, the IC chips in a back-to-back configuration; (b) the IC chip and the printed circuit board surround the heat sink means and the IC chip; electrically bonded to each other via a single circuitized flexible tape,
The high density microelectronic circuit package of claim 1. 3. (a) an IC chip is bonded to the heat sink means on a second heat transfer surface thereof, at least one IC chip is bonded to one side of the heat sink means and at least one other is bonded to the heat sink means; an IC chip is adhered to the other side of the heat sink means, the IC chip being in a back-to-back configuration; (b) the IC chip and the printed circuit board are connected to a pair of circuitized flexible tapes; , wherein one of the tapes is adhered to one side of the heat sink means and the other of the tape is adhered to the other side of the heat sink means. 2. The high-density microelectronic circuit package according to 2. 4. Further, (a) a circuitized flexible tape on one side capable of receiving and adhered to the input/output terminal array on the first side of the input/output contacts of the IC chip; a first input/output contact pad array; (b) connected to the first input/output contact pad array by a via and capable of receiving and adhered to an array of input/output pads on a printed circuit board; , and a second input/output contact pad array on the other side of the circuitized flexible tape. 5. The package extends outwardly from the printed circuit board and includes: (a) a second input/output pad array on the circuitized flexible tape and an input/output pad on the printed circuit board; is electrically connected to the printed circuit board through (
b) thermally connected to the printed circuit board via the heat transfer surface of the IC chip adhered to the heat sink means;
The high density microelectronic circuit package of claim 1. 6. The input/output pad on the circuitized flexible tape is tape-automatically bonded.
Microelectronic circuit package as described. 7. The microelectronic circuit package of claim 1 including a thermal adhesive between at least one of said integrated circuit chips and said heat sink means. 8. The microelectronic circuit package of claim 7, wherein said thermal adhesive comprises solder. 9. The microelectronic circuit package of claim 7, wherein said thermal adhesive comprises thermal grease. 10. A circuitized flexible tape extends beneath the heat sink means, the heat sink means being adhered to the printed circuit board via the circuitized flexible tape. The high density microelectronic circuit package of claim 1. 11. (a) a plurality of IC memory chips;
(b) a printed circuit board; (c) a circuitized flexible tape; (d) a circuitized flexible tape extending outwardly from the printed circuit board; It extends to
and a plurality of IC chips are attached to input/output pads thereon, the input/output pads are arranged in at least first and second groups, (1) the first group of input/output pads is (2) a second group of input/output pads are connected to a common bus of the first connector, the common bus terminating in an array of input/output contact pads on the edge of the flexible tape; (e) a circuitized flexible tape I/O pad array connected to a second group of conductors extending outwardly from the chip toward an I/O pad array on a printed circuit board; aligned with the array of contact pads;
and a high-density microelectronic circuit package bonded to it. 12. Further comprising: (a) heat sink means extending outwardly from the printed circuit board; (b) each having an input/output contact first side and a thermal contact second side; an IC chip adhered to the circuitized flexible tape by the output contact first side and to the heat sink means by the IC chip thermal contact second side. Density microelectronic circuit package. 13. Further, (a) a first input of a circuitized flexible tape capable of receiving and adhered to an input/output terminal array on a first surface of input/output contacts of the IC chip; Output contact pad/
a first input/output contact pad array on one side of the array; (b) connected to the first input/output contact pad array by a via and capable of receiving an array of input/output pads on a printed circuit board; 13. The high density microelectronic circuit package of claim 12, further comprising a second input/output contact pad array on the other side of the circuitized flexible tape connected thereto. 14. A package extending outwardly from the printed circuit board, the package comprising: (a) a second input/output pad array on the circuitized flexible tape and an input/output pad on the printed circuit board; (b) thermally connected to the printed circuit board via a heat transfer surface of the IC chip adhered to the heat sink means;
High-density microelectronic circuit package as described. 15. (a) each IC chip is bonded to a heat sink means on the second thermal side, and includes at least one IC chip;
a C chip is adhered to one side of the heat sink means, and at least one IC chip is adhered to the other side of the heat sink means, the IC chips being in a back-to-back configuration; (b) said 15. The high-density ultra high-density ultrasonic device of claim 14, wherein the IC chip and the printed circuit board are electrically connected to each other via a single circuitized flexible tape surrounding the heat sink means and the IC chip. Small electronic circuit package. 16. (a) each IC chip is bonded to a heat sink means on the second thermal side, and includes at least one IC chip;
a C chip is adhered to one side of the heat sink means, and at least one IC chip is adhered to the other side of the heat sink means, the IC chips being in a back-to-back configuration; (b) said the IC chips are electrically adhered to each other via a pair of circuitized flexible tapes, one of the tapes being adhered to one side of the heat sink means;
15. The high density microelectronic circuit package of claim 14, wherein the other side of the tape is adhered to the other side of the heat sink means. 17. The circuitized flexible tape contact pad array is tape autobonded;
12. The high density microelectronic circuit package of claim 11. 18. A thermal adhesive between at least one of said integrated circuit chips and said heat sink means.
13. The microelectronic circuit package of claim 12. Claim 19: The thermal adhesive is made of solder.
The microelectronic circuit package of claim 18. 20. The microelectronic circuit package of claim 18, wherein said thermal adhesive comprises thermal grease. 21. A circuitized flexible tape extends beneath the heat sink means, the heat sink means being adhered to the printed circuit board via the circuitized flexible tape. 12. The high density microelectronic circuit package of claim 11.