JP2007005477A - Noise removal method by underfill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a utilizing method of underfill which raises device performance by using underfill at least one or more kinds of material characteristics. <P>SOLUTION: In the application method of the underfill: the underfill material is filled in between different substrates, the relative permittivity or the relative magnetic permeability of the underfill material is adjusted, and the gain of frequency band of the noise generated in a joining terminal and a metal conductive pattern of the above board is attenuated. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to application of underfill used in an integrated circuit, and more particularly to a technique for removing noise using the underfill.

  Conventionally, the underfill is used to improve the bonding strength when an LSI (integrated circuit) such as a BGA (Ball Grid Array) package is mounted on a substrate. For example, when used in environments such as mobile devices such as vibrations, shocks, or temperature changes, the bonding strength cannot be maintained by simply connecting the LSI terminals and the motherboard (substrate) electrodes with solder balls. Therefore, it is necessary to improve the bonding strength using an underfill. An insulating material is used as the underfill material.

  However, with the recent miniaturization of devices, it is difficult to secure a component mounting space, and it is difficult to secure a space for mounting components around the LSI. An LSI basically functions alone, but in most cases, it is necessary to mount components necessary for improving the performance of the LSI in addition to the LSI on the motherboard (for example, a bypass capacitor). Therefore, it is necessary to design a board in consideration of the component mounting position, which leads to an increase in the number of components and an increase in cost.

  Further, a noise component may be transmitted from the LSI. These noises become floor noises and the like, leading to a decrease in dynamic range. Many LSIs used for communication devices operate in a high frequency band such as RF (Radio frequency), and leakage of high frequency components causes VCCI (Radio Frequency Interference Regulations for Information Processing Equipment), FCC (Federal). There are cases where problems such as falling outside the standards defined by Communications Commission) occur.

  Further, there are cases where an LSI is designed in such a direction that many functions are packed in one package as much as possible. Therefore, recently, there are many LSIs in which analog circuits and digital circuits are mixed in one package. In such a case, a digital system noise may be superimposed on an analog system, and vice versa. In addition, a noise component may be superimposed on the input / output of the LSI, and various effects may be exerted on the device.

  Also, according to Patent Document 1, high-density area array connection of chips and terminals is possible, delay and noise are eliminated by lowering the dielectric constant and shortening the internal wiring length, and resistance is improved by underfill and encapsulant. Proposals have been made to improve stress and moisture resistance reliability. According to Patent Document 2, there is a proposal that a resin-encapsulated semiconductor device having a low dielectric loss due to a low relative dielectric constant and good noise characteristics can be easily obtained.

  According to Patent Document 3, since the resin covering the side surface of the circuit board has a high dielectric constant, the wavelength of the electromagnetic wave can be shortened to 1 / √εr (εr is a relative dielectric constant) of free space. It has been proposed that the data carrier itself can be reduced in size, and that the size can be reduced without impairing the flexibility of the circuit board or the sealing resin.

However, although the methods described in Patent Documents 1, 2, and 3 use an underfill material, they are not methods for positively removing noise components by providing filter characteristics to the underfill material.
JP-A-6-244320 Japanese Patent Laid-Open No. 9-064236 JP 2002-222398 A

  The present invention has been made in view of the above circumstances, and provides an underfill coating method that uses an underfill having at least one kind of characteristic and removes noise components of equipment to improve performance. For the purpose.

  The underfill coating method according to one aspect of the present invention includes injecting an underfill material between different substrates, adjusting a relative permittivity or a relative permeability of the underfill material, and connecting terminals of the substrate. Further, the present invention is characterized in that the gain in the frequency band of noise generated in the metal conductor pattern is attenuated.

  When the underfill material is injected, an underfill material corresponding to the type of noise generated from the connection terminal or the metal conductor pattern may be applied in the vicinity of the connection terminal or the metal conductor pattern. .

  Further, the characteristics of the underfill material are set as filter characteristics by providing an open stub in the vicinity of the predetermined connection terminal and the metal conductor pattern in the coating range, and adjusting the relative permittivity or relative permeability.

  Further, the characteristics of the underfill material are set as filter characteristics by providing a meander line in the vicinity of the predetermined connection terminal and the metal conductor pattern in the coating range and adjusting the relative permittivity or relative permeability.

  In addition, the characteristics of the underfill material are determined by providing an open stub and a meander line in the vicinity of the predetermined connection terminal and the metal conductor pattern within the coating range, and adjusting the relative permittivity or the relative permeability. It has resonance characteristics.

The underfill material has only one of a relative permittivity and a relative permeability.
Further, the characteristics of the underfill material are set as filter characteristics by providing a spiral in the vicinity of the predetermined connection terminal and the metal conductor pattern within the coating range and adjusting the relative permittivity or relative permeability.

  In addition, the characteristics of the underfill material are resonances having an attenuation pole by providing an open stub and a spiral in the vicinity of the predetermined connection terminal and the metal conductor pattern within the coating range, and adjusting the relative permittivity or relative permeability. Characteristic.

  In the underfill coating method according to one aspect of the present invention, two or more types of underfill materials are injected in accordance with the characteristics of each electrode between different substrates, and the relative permittivity or relative permeability of the underfill material is injected. The magnetic susceptibility is adjusted to attenuate the frequency band gain of noise generated in the connection terminal and the metal conductor pattern of the substrate.

  According to the present invention, the number of parts can be reduced, and further, the influence of noise components generated by the device itself and external noise can be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Next, a method for removing noise components by using a plurality of underfills having different characteristics will be described as a method of using the underfill material other than improving the bonding strength. FIG. 1A is a diagram in which an IC 1 manufactured in a BGA package is mounted on a mother board 2 (substrate).

  In the IC 1 of the BGA package, for example, an integrated circuit (LSI) 3 is mounted on an interposer 4 (substrate), and the electrodes of the integrated circuit 3 and the electrodes on the interposer 4 are connected by wires 5. Next, a resin is injected between the shield case 6 and the interposer 4. A solder ball, which is the connection terminal 7 of the IC 1 of the BGA package shown in this example, and a pattern (metal conductor) formed on the mother board 2 are joined by solder.

  However, in the interposer 4 and the mother board 2, various changes occur on the substrate due to environmental changes. For example, if the temperature changes, the substrate will expand and contract due to heat. Further, if the humidity changes, the substrate may be deformed due to water absorption by the substrate. Such a change in the substrate may cause the solder balls to be peeled off from the interposer 4 or the mother board 2 and be lost. Therefore, usually the underfill 8 is injected between the interposer 4 and the mother board 2 and joined to improve the joining strength.

  A connection terminal 7 surrounded by a dotted line indicated by a dotted line range 9 in FIG. 1 is an RF signal input terminal. The connection terminal 7 surrounded by the dotted line indicated by the dotted line range 10 is an RF signal output terminal. A dotted line range 11 is a power supply terminal, and a dotted line range 12 indicates a logic interface (such as an input / output terminal for a control signal).

  Further, in the case of BGA terminals arranged as shown in FIG. 1A, a plurality of underfills 8a and 8b are applied as shown in FIG. 1B (here, the mother board 2 is shown in the bottom view). The underfill materials 8a and 8b are shown together for convenience). An underfill material 8a made of a material having a low loss, a low dielectric constant, and a low magnetic permeability is applied to the RF block (RF signal input terminal 9 and RF signal output terminal 10).

  For the power supply block (dotted line range 11: power supply terminal) and control block (dotted line range 12: control signal input / output terminal), an underfill material 8b made of a material with high loss, high dielectric constant, and high magnetic permeability is applied. To do.

Since the power supply block and the control block have high impedance due to the characteristics of the underfill material, it is difficult to propagate harmonic components from the outside.
Further, by increasing the loss, unnecessary harmonic components are converted into heat and made electrically harmless, so it is possible to further take measures against noise.

As described above, by using a dielectric material or a magnetic material as the underfill material, it is possible to give the feed line portion a filter characteristic.
As the dielectric material, a high dielectric material such as barium titanate or a resin material such as epoxy is used. The magnetic material is a high permeability material such as ferrite or a resin material such as epoxy.

The application pattern shown in FIG. 1 needs to consider the characteristics of the underfill material 8 and the application pattern depending on the arrangement of the connection terminals of the IC 1 in order to increase the noise removal efficiency.
(Underfill material simulation)
A configuration in which the above-described underfill material is made of a dielectric material and a magnetic material and the feed line portion has a filter characteristic will be described using simulation results.

The simulation condition is that the motherboard 2 side line is a 50Ω microstrip line (MSL line), the line width = 1.5 mm, the base material thickness = 0.8 mm, and the base material εr = 4.4.
The interposer 4 (BGA product, etc.) side line is also a 50Ω microstrip line, the line width = 0.7 mm, the base material thickness = 0.3 mm, and the base material εr = 4.4.
Example 1
FIG. 2 shows a diagram in which the metal conductor 13 provided on the interposer and the metal conductor 14 provided on the mother board 2 are connected by the connection terminal 7 (corresponding to the solder ball 7 shown in FIG. 1). An underfill material 8 is applied between the mother board 2 and the interposer 4. For the connection terminal 7, a simulation was performed in which vertical power feeding was performed to the mother board 2 and the interposer 4, and the S parameter was measured by changing the frequency from 0 to 1.2 GHz. Here, in this simulation, in order to measure a region of several MHz or more, S parameters that can be easily measured in a state where input / output is terminated with characteristic impedance are used. In particular, paying attention to S21 (forward transmission coefficient), S11 (input reflection coefficient) and S22 (output reflection coefficient) are also shown in the graph.

  FIG. 3 shows a simulation result when the underfill constant is set to the relative permittivity εr = 1, the loss coefficient tan δ = 0 / the relative permeability μr = 1, and the loss coefficient tan δ = 0 in the configuration of FIG.

The loss coefficient tan δ is represented by tan δ = εr ″ / εr ′ in the case of the dielectric constant, and is represented by tan δ = μr ″ / μr ′ in the case of the magnetic permeability.
S21 is 0 [dB] at 50 MHz, 0.02 [dB] at 250 MHz, 0.03 [dB] at 550 MHz, 0.05 [dB] at 750 MHz, and 0.07 [dB] at 1050 MHz It becomes.

  FIG. 4 shows a simulation result when the underfill constant is set to the relative dielectric constant εr = 100, the loss coefficient tan δ = 0 / the relative permeability μr = 1, and the loss coefficient tan δ = 0 in the configuration of FIG.

S21 is 0.02 [dB] at 50 MHz, 0.40 [dB] at 250 MHz, 1.62 [dB] at 550 MHz, 2.65 [dB] at 750 MHz, and 4.23 at 1050 MHz. dB].
(Example 2)
Next, FIG. 5 shows a diagram in which the metal conductor 13 provided on the interposer and the metal conductor 14 provided on the mother board 2 are connected by the connection terminal 7 (corresponding to the solder ball 7 shown in FIG. 1). . At this time, the open stub 15 is connected to the connection terminal 7 on the mother board 2 and provided in the vicinity. An underfill material 8 is applied between the mother board 2 and the interposer 4. For the connection terminal 7, a simulation was performed in which the mother board 2 and the interposer 4 were vertically fed to change the frequency from 0 to 1.2 GHz and measure the S parameter.

FIG. 6 shows a detailed drawing of FIG. The open stubs 15 are arranged on the mother board 2 on the left and right sides with the connection terminals 7 approximately at the center.
In this embodiment, the open stub 15 is laid out on the mother board 2 side, but can also be laid out on the interposer 4 side.

Moreover, although the rectangular stub was used in the simulation, a butterfly type (fan shape) or the like may be used.
FIG. 7 is a simulation result when the underfill constant is set to a relative dielectric constant εr = 100, loss coefficient tan δ = 0.1 / relative magnetic permeability μr = 1, and loss coefficient tan δ = 0 in the configuration of FIG.

  S21 is 0.99 [dB] at 50 MHz, 7.61 [dB] at 250 MHz, 13.74 [dB] at 550 MHz, 16.46 [dB] at 750 MHz, 19.64 [1050] at 1050 MHz. dB].

Here, in Example 1, when the relative permittivity is 100, S21 can only attenuate about 4 [dB] in the vicinity of 1 GHz. However, by devising the power feeding portion pattern and adding an open stub, 20 [dB It can be attenuated to a degree. Further, it is possible to further increase the attenuation by optimizing the metal conductor pattern.
(Example 3)
Next, FIG. 8 is a diagram in which the metal conductor 13 provided on the interposer and the metal conductor 14 provided on the mother board 2 are connected by the connection terminal 7 (corresponding to the solder ball 7 shown in FIG. 1). Show. At this time, the meander line 16 is extended from the connection terminal 7 on the mother board 2 and provided near the connection terminal 7. An underfill material 8 is applied between the mother board 2 and the interposer 4. For the connection terminal 7, a simulation was performed in which the mother boat 2 and the interposer 4 were vertically fed to change the frequency from 0 to 1.2 GHz and the S parameter was measured.

  FIG. 9 shows a detailed drawing of FIG. In this embodiment, since the meander line 16 is a high impedance line, it is laid out narrower than the 50Ω line, the line width = 0.1 mm, the gap 0.1 mm, and the number of turns = 10.

The meander line 16 is laid out on the mother board 2 side, but may be arranged on the interposer 4 side.
Moreover, the same effect can be obtained even if the layout is circular or rectangular and spiral.

  FIG. 10 shows a simulation result when the underfill constant is set to the relative dielectric constant εr = 1, the loss coefficient tan δ = 0 / the relative permeability μr = 1, and the loss coefficient tan δ = 0 in the configuration of FIG.

  S21 is 0.2 [dB] at 50 MHz, 0.08 [dB] at 250 MHz, 0.19 [dB] at 550 MHz, 0.29 [dB] at 750 MHz, and 0.49 [at 1050 MHz. dB].

  FIG. 11 shows a simulation result when the underfill constant is set to the relative permittivity εr = 1, the loss coefficient tan δ = 0 / the relative permeability μr = 1000, and the loss coefficient tan δ = 0 in the configuration of FIG.

  S21 is 0.43 [dB] at 50 MHz, 5.31 [dB] at 250 MHz, 10.71 [dB] at 550 MHz, 12.79 [dB] at 750 MHz, and 12.03 at 1050 MHz. dB].

When the relative magnetic permeability = 1000, it is possible to obtain a 1 GHz attenuation of about 12 [dB] by arranging a meander line. The meander line is for obtaining the L component. If a high impedance line is used, the same effect can be obtained even if a spiral or the like is used. Furthermore, a large amount of attenuation can be obtained by optimizing the pattern.
Example 4
Next, FIG. 12 is a diagram in which the metal conductor 13 provided on the interposer and the metal conductor 14 provided on the mother board 2 are connected by the connection terminal 7 (corresponding to the solder ball 7 shown in FIG. 1). As shown in FIG. At this time, an open stub 15 and a meander line 16 are extended from the connection terminal 7 on the mother board 2 and provided near the connection terminal 7. An underfill material 8 is applied between the mother board 2 and the interposer 4. The connection terminal 7 was fed with vertical power to the mother board 2 and the interposer 4, and a simulation was performed in which the S parameter was measured while changing the frequency from 0 to 1.2 GHz.

  FIG. 13 shows a detailed drawing of FIG. By laying out a meander line and an open stub on the motherboard 2, an electrical component is obtained by configuring an inductance component (such as a meander line) and a capacitance component (such as an open stub).

  FIG. 14 shows simulation results when the underfill constant is set to a relative dielectric constant εr = 100, loss coefficient tan δ = 0 / relative magnetic permeability μr = 1000, and loss coefficient tan δ = 0 in the configuration of FIG.

  S21 is 0.22 dB at 50 MHz, 32.15 [dB] at 150 MHz, 31.83 [dB] at 300 MHz, 34.57 [dB] at 600 MHz, and 35.67 [dB] at 1000 MHz. Become.

  A resonance circuit can be formed by combining an open stub and a meander line in the power supply unit, and an attenuation pole can be formed. In the simulation, an attenuation amount at the attenuation pole of 30 [dB] or more was obtained.

  The attenuation pole can be set to a desired frequency point by adjusting the layout of the metal conductors 13 and 14 and the connection terminal 7, the dielectric material of the underfill material, and the constant of the magnetic material, and can be applied to a desired harmonic cut. I can do it.

With the above configuration, a bypass capacitor effect can be obtained by using a high dielectric constant material.
In order to further improve the noise removal efficiency, the layout is made in consideration of the characteristics of each underfill material. For example, the size of the electrode on the substrate surface to which the solder ball is connected and the shape of the solder ball are changed.

  In the above-described embodiment, the cutoff frequency can be shifted to the low frequency side by lengthening the high impedance line (including meander, spiral, etc.) and increasing the impedance. Moreover, the cutoff frequency can be shifted to the low frequency side by increasing the size of the stub and making the transmission line thicker (lowering the impedance).

  As a matter of course, if the interposer 4 and the mother board 2 are known to be easily peeled off and difficult to peel off, use appropriate underfills at appropriate locations using multiple types of underfill with different underfill curing. Apply the appropriate amount of material.

  The present invention is not limited to the above-described embodiment, and various improvements and modifications can be made without departing from the gist of the present invention.

It is (a) side view and (b) bottom view which show this invention. It is a figure which provides an underfill between a motherboard and an interposer and performs vertical electric power feeding. FIG. 3 is a diagram showing a simulation result with an underfill constant εr = 1, tan δ = 0 / μr = 1, and tan δ = 0 in the configuration of FIG. 2. FIG. 3 is a diagram showing a simulation result with an underfill constant εr = 100, tan δ = 0 / μr = 1, and tan δ = 0 in the configuration of FIG. 2. It is a figure which provides an underfill between a mother board and an interposer, and also provides an open stub in a power feeding unit to perform vertical power feeding. FIG. 6 is a top view of FIG. 5. FIG. 6 is a diagram showing a result of simulation with an underfill constant εr = 100, tan δ = 0.1 / μr = 1, and tan δ = 0, with an open stub added to the power feeding unit in the configuration of FIG. 5. It is a figure which provides an underfill between a mother board and an interposer, and also adds a meander line to a feed part and performs vertical feed. FIG. 9 is a top view of FIG. 8. FIG. 8 is a diagram illustrating a simulation result of adding an underfill constant εr = 1, tan δ = 0 / μr = 1, and tan δ = 0 and adding a meander line to the power feeding unit in the configuration of FIG. 7. FIG. 8 is a diagram illustrating a result of simulation with a underfill constant εr = 1, tan δ = 0 / μr = 1000, and tan δ = 0 in the configuration of FIG. It is a figure which performs vertical electric power feeding by providing an underfill between a motherboard and an interposer and further adding an open stub and a meander line to the power feeding section. FIG. 13 is a top view of FIG. 12. FIG. 11 is a diagram illustrating a result of simulation with an underfill constant εr = 100, tan δ = 0 / μr = 1000, and tan δ = 0, with an open stub and a meander line added to the power feeding unit in the configuration of FIG. 10.

Explanation of symbols

1 ... IC
2 ... Motherboard (substrate)
3 ... Integrated circuit (LSI)
4 ... Interposer (substrate)
5 ... Wire 6 ... Shield case 7 ... Connection terminal (solder ball)
8: Underfill 8a: Underfill material composed of low loss, low dielectric constant, low magnetic permeability material 8b: Under, composed of high loss, high dielectric constant, high magnetic permeability material Fill material 9 ... RF block (RF signal input terminal)
10 ... RF block (RF signal output terminal)
11 ... Power supply block (power supply terminal)
12 ... Control block (input / output terminals for control signals)

Claims (9)

  Injecting underfill material between different substrates and adjusting the relative permittivity or relative permeability of the underfill material to attenuate the frequency band gain of noise generated at the connection terminal and metal conductor pattern of the substrate An underfill coating method characterized by comprising:   When the underfill material is injected, an underfill material corresponding to the type of noise generated from the connection terminal or the metal conductor pattern is applied in the vicinity of the connection terminal or the metal conductor pattern. Item 2. The underfill coating method according to Item 1.   A characteristic of the underfill material is a filter characteristic by providing an open stub in the vicinity of the predetermined connection terminal and the metal conductor pattern within a coating range, and adjusting a relative permittivity or a relative permeability. The underfill coating method according to claim 1.   A characteristic of the underfill material is a filter characteristic by providing a meander line in the vicinity of the predetermined connection terminal and the metal conductor pattern within a coating range, and adjusting a relative permittivity or a relative permeability. The underfill coating method according to claim 1.   Resonance having an attenuation pole by adjusting the relative permittivity or relative permeability of the underfill material by providing an open stub and a meander line in the vicinity of the predetermined connection terminal and the metal conductor pattern within the coating range. The underfill coating method according to claim 1, wherein the underfill coating method is characterized.   The underfill coating method according to claim 1, wherein the underfill material has only one of a relative permittivity and a relative permeability.   The characteristic of the underfill material is a filter characteristic by providing a spiral in the vicinity of the predetermined connection terminal and the metal conductor pattern within a coating range and adjusting a relative permittivity or a relative permeability. Item 2. The underfill coating method according to Item 1.   The characteristic of the underfill material is a resonance characteristic having an attenuation pole by providing an open stub and a spiral in the vicinity of the predetermined connection terminal and the metal conductor pattern within a coating range, and adjusting a relative permittivity or a relative permeability. The underfill coating method according to claim 1, wherein: Two or more types of underfill materials are injected in accordance with the characteristics of each electrode between different substrates, and the relative permittivity or relative permeability of the underfill material is adjusted to provide the connection terminals and metal conductors of the substrate. A method of applying an underfill, comprising attenuating a gain in a frequency band of noise generated in a pattern.

Images