JPS62154746A - Bonding method for electronic part - Google Patents

Abstract

PURPOSE:To ensure the conduction and connection of electronic parts and the terminal parts of the surface of a substrate and to prevent short circuits between neighboring terminal parts perfectly, by forming the part-connecting terminal parts by the printing of a bonding agent, in which conductive particles are mixed in heat fusible type paste, depositing a heat fusible insulating bonding agent on a part-bonding part including the upper surface of the part-connecting terminal parts, and bonding the electronic parts and the substrate with said insulating bonding agent. CONSTITUTION:LSI-pellet connecting terminal parts 2a and 2a are formed on the surface of a wiring substrate 1, by the printing of a bonding agent, A, in which conducting particles 5 and 5 are mixed in heat fusible carbon paste. Thus the conductive particles 5 and 5 are present only in the LSI-pellet connecting terminal parts 2a and 2a. A heat fusible insulating bonding agent 6 is deposited on the LSI-pellet bonding parts on the surface of the wiring substrate 1 including the upper surface of the LSI-pellet connecting terminal parts 2a and 2a. An LSI-pellet 10 and the wiring substrate 1 are bonded with said insulating bonding agent 6. Therefore, the conductive particles are not present between the neighboring LSI-pellet connecting terminal parts 2a and 2a on the surface of the wiring substrate 1. Thus no short circuit is present among the wiring substrate 1, the LSI-pellet 10, the neighboring terminal parts 2a and 2a and terminal parts 11 and 11.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a method for joining electronic components, in which electronic components are joined on a side-to-side basis.

(Technical background of the invention and its problems) When connecting electronic components such as semiconductor pellets to the wiring board surface, conventionally a single connection method using wire bonding has been adopted, but this wire bonding is inefficient. Therefore, recently, anisotropic conductive adhesives, in which conductive particles are mixed into hot-melt type 1 insulating adhesives at a mixing rate that prevents the particles from touching each other, have been used to bond wiring board surfaces. Adhesive bonding of electronic components is being considered.

This method of joining electronic components includes attaching the upper surface of the component I8 connecting terminal portion, which is formed in the electronic component joining portion on the surface of the wiring board 1, to the electronic component joining portion in correspondence with the terminal portion of the electronic component. The above-mentioned anisotropic 54 electric adhesive is applied by screen printing, and electronic components are stacked and heat-pressed on top of the adhesive with the terminals thereof facing the component connection terminals, and the adhesive is applied to the wiring board surface. When electronic components are placed on top of the adhesive layer and heated and pressurized, the insulating adhesive melts and the insulating adhesive between the electronic components and the terminals on the board surface is pushed out to the surroundings, causing the contact between the electronic components and the board surface. Since the terminal parts come in contact with the conductive particles between the terminal parts and are electrically connected to each other, if the adhesive is cured in the open state, the terminal parts of both the electronic component and the wiring board can be electrically connected. Can be glued together while connected to.

However, in the method for bonding electronic components using the above-mentioned anisotropic conductive adhesive, conductive particles mixed into the anisotropic conductive adhesive during heating and pressurization are mixed with the adhesive from above the terminal part on the board surface to between the terminal part. Because it flows, it has serious drawbacks such as poor conductivity between electronic components and terminals on the board surface, and short circuits between adjacent terminals. The joining method has not been used in actual seedling production until now.

(Objective of the Invention) This invention was made in view of the above-mentioned circumstances, and its purpose is to provide a method for adhesively bonding electronic components to a substrate surface, and to The object of the present invention is to provide a method for mounting electronic components that can reliably conductively connect terminal parts and completely prevent short circuits between adjacent terminal parts, thereby greatly improving reliability and yield.

[Summary of the invention]

That is, the present invention prints a bonding agent containing conductive particles in a heat-melting paste on a substrate surface to form a component connection terminal portion corresponding to a terminal portion of an electronic component, and then dries this bonding agent. After that, a hot-melt insulating adhesive is applied to the component joint portion on the board surface, including the upper surface of the component connection terminal, and the electronic component is rolled and heat-pressed on top of the adhesive, thereby forming the board. Electronic components are adhesively bonded to the surface.

In other words, the present invention forms the component connection terminal portions formed on the board surface by printing a bonding agent containing conductive particles in a heat-melting paste, thereby allowing the conductive particles to exist only in the terminal portions. , a hot-melt insulating adhesive is applied to the component joint portion of the board surface, including the upper surface of the component connection terminal portion, and the electronic component and the board are bonded with this insulating adhesive. According to this invention, since there are no conductive particles between adjacent terminal parts, there is no short circuit between adjacent terminal parts, and it is also possible to increase the amount of particles in the bonding agent. Therefore, it is possible to increase the number of particles in the terminal portion and reliably conductively connect the electronic component and the terminal portion on the board surface.

[Examples of inventions]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings regarding joining of LSI bullets.

Figure 1 shows the method for joining the LSI bullet in the order of steps, Figure 2 shows the state when the LSI bullet is joined to the wiring board surface, and Figure 3 shows the state in which the LSI bullet is joined to the wiring board surface. It shows.

First, a description will be given of the wiring board to which the LSI bullet is bonded. In FIGS. 2 and 3, 1 is the wiring board. This wiring board 1 has a large number of wirings 2.2 formed in a pattern as shown in FIG. 2 on a film substrate 1a made of a resin film such as polyester or polyimide. LSI on board 1
It is derived from the bullet joint, and the L of each wiring 2.2
The end on the SI bullet joint side is connected to a large number of terminal parts 11° 11 arranged on the main surface (wiring board joint surface) of the LSI bullet 10 along its outer periphery, and LSI bullet connections corresponding thereto. These are terminal portions 2a, 2a. This wiring 2.2 and LSI bullet connection terminal section 2
a and 2a have a two-layer structure in which a heat-melting conductive paste layer, such as a carbon paste (also referred to as carbon ink) layer 4, is formed on a conductive metal layer 3 made of copper, aluminum, etc. A plurality of conductive particles (solder particles, nickel particles, etc.) 5.5 having a diameter larger than the layer thickness are buried in the layer 4 at approximately constant intervals. Note that the carbon paste pads 4, 4 in the upper layer of the wiring 2.2 serve as an oxidation prevention film for the conductive metal layer 3 below. Also,
Reference numeral 6 denotes a heat-melting insulating adhesive which is applied to the LSI bullet joint portion of the wiring board 1, including the upper surface of the LSI bullet connection terminal portions 2a, 2a, with /v;
connects each terminal portion 11.11 to each LSI on one side of the wiring board.
The terminal portions 11.11 of the LSI pellet 10 are bonded to the conductive particles 5 by the insulating adhesive 6 while facing the pellet connecting terminal portions 2a, 2a.
．． 5 to each LSI bullet connection terminal portion 2a on one side of the wiring board.

It is electrically connected to 2a.

Each terminal portion 11° 11 of the LSI pellet 10 has a structure in which a bump 13 made of gold, solder, carbon, etc. is formed on a terminal electrode pad 12 made of aluminum or the like, and the bump 13 made of gold, solder, carbon, etc. 5, 5 are in contact with the bump 13 on the surface of this terminal portion. Further, in FIG. 3, 20 is a molding resin such as epoxy resin for molding the LSI bullet 10 bonded to one surface of the wiring board, and this mold resin 20 is applied after the LSI bullet 10 is bonded. .

Next, a method for joining the LSI pellet 10 will be explained with reference to FIG.

In this bonding method, first, a two-layer structure consisting of a conductive metal layer 3 and a carbon paste layer 4 mixed with conductive particles 5.5 is arranged on the surface of the film substrate 18! ! 2.2 and L
SI bellet connection terminal section 2a.

2a to manufacture the wiring board 1, and then the wiring lj1
The LSI pellet 10 is adhesively bonded to the wiring board 1 by applying a heat-melting type insulating adhesive 6 to the LSI pellet joint on the surface of the substrate 1, placing the LSI pellet 10 thereon and heat-pressing it. The wiring board 1 is manufactured as follows.

First, as shown in FIG. 1(a), copper or aluminum foil is laminated over the entire surface of the board (1) and then distributed (2).
2 and LSI bullet connection terminal portions 2a, a film substrate 1a on which an S-conductive metal layer 3 is formed, which becomes the lower layer portion of 2a.
A mesh screen 7 is placed thereon at a predetermined interval (an interval approximately equal to the diameter of the conductive particles 5.5), and on top of that, an LSI bullet connection terminal portion 2a formed on the wiring board 1, 2a and a hard screen (metal screen, etc.) 8 having openings 3a and aa corresponding to the patterns of the wirings 2 and 2, and conductive particles are placed on top of the hard screen (metal screen, etc.) 8 in a carbon paste whose viscosity has been lowered by mixing a solvent. Bonding agent A mixed with 5.5 at a high mixing rate is printed on the surface of the film substrate 1a (above the conductive gold mud layer 3), and the LSI bellets corresponding to each terminal portion 11° 11 of the LSI pellet 10 are printed.
A bonding agent for the connecting terminal portion 1a and the wiring pattern connected thereto is applied to one surface of the film substrate. In addition, in FIG. 1(a), 9 is a squeegee, and the bonding agent A is spread on the hard screen 8 by this squeegee 9, and passes through the frontages Ba, Ba of the hard screen 8 and the mesh screen 7. A mark e11 is made on the surface of the film substrate 1a.

Further, the mesh screen 7 has a film substrate 18
In order to distribute the conductive particles 5, 5 in the bonding agent A to be printed at equal intervals, this mesh screen 7 is used.
is an open lower a slightly larger than the diameter of the conductive particle 5.5
, 7a are formed at evenly spaced minute intervals.

In this way, each terminal portion 11.1 of the LSI bullet 10
After printing the bonding agent A for the LSI bullet connection terminals corresponding to 1 and the wiring patterns connected thereto on one side of the film substrate, dry the bonding agent A printed on the 18th side of the film substrate, and then remove the bonding agent. A is fixed on the film substrate 10.

When this bonding agent A is dried, the solvent in the carbon base evaporates, and the thickness of the carbon paste layer 4 decreases by that amount as shown in FIG. 1(b), and the conductive particles 5,
The upper part of 5 is now in a state of protruding above the carbon base WJJ. The particle size of the conductive particles 5.5 is selected to be about 1.5 to 3 times the layer thickness of the carbon-based layer 4 after drying.

Thereafter, the conductive metal layer 3 laminated over the entire surface of the film substrate 1a is removed by etching with an etching solution using the bonding agent A imprinted thereon as a mask, as shown in FIG. 1(C). A two-layer structure consisting of a conductive metal layer 3, a carbon base 1 mixed with conductive particles 5, and a layer 4 (arrangement in which M-structure wiring 2, 2 and LSI bullet connection terminal portions 2a, 2a are formed) !11L plate 1 is completed. Note that the portions of the conductive particles 5.5 in the bonding agent A that protrude above the carbon paste layer 4 are also thinly covered by the carbon paste adhering to the surface. Therefore, when etching the conductive metal layer 3, the conductive particles 5, 5 are never etched.

Therefore, this corrosion is first applied to the outer circumferential portion of the connection portion of the wiring board 1 to the LSI beret 1, including the upper surface of the LSI belet connection terminal portions 2a, 2a, using the heat-melting insulating adhesive 6.
is printed and adhered by screen printing as shown in FIG. 1(d), and the LSI bullet 10 is placed thereon, and each terminal portion 11.11 of the LSI bullet 10 is attached to each LSI bullet connection terminal portion 2a, 2a on one side of the wiring board. The LSI pellet 10 and the wiring board 1 are overlapped in a facing state (see FIG. 2), and are heated and pressed together using a heating and pressing jig (not shown). When the St pellet 1o is placed on top of the heat-melting insulating adhesive 6 and heated and pressed, the heat-melting insulating adhesive 6 melts and connects the terminal portions 11 and 11 of the LSI pellet 10 to the wiring board. 1 side LSI
Insulating adhesive 6 between the bullet connection terminal parts 2a and 2a
are extruded to the surroundings, so that the conductive particles 5, 5 held in the carbon paste layers 4, 4 by the pressurizing force are
As shown in Figure (e), the terminal section 11 of the LSI bullet 10
．． 11, and the terminal portion 11.1 of the LSI bullet 10.
11 and the LSI bullet connection terminal part 2a on one side of the wiring board,
2a are electrically connected via conductive particles 5.5. Also, at this time, the LSI bellet connection terminal portions 2a, 2a
Since the carbon paste layer 4.4 is also melted, the conductive particles 5.5 come into direct contact with the conductive metal layer 3.3 below the LSI pellet connection terminal portions 2a, 2a. The conduction between the conductive particles 5.5 and the LSI pellet connecting terminal portions 2a, 2a can be further improved. In addition,? 8. The melted carbon paste is also extruded around the terminal part by the pressure, but the amount is very small, so the conductive particles 5.5 held in the carbon paste layer 4.4 are pushed out around the terminal part. It will not be extruded together with the carbon base 1 which is extruded around the part.

This model can be achieved by curing the insulating adhesive 6 while maintaining the pressurized state, and by curing the insulating adhesive 6, the L
The SI bellet 10 and the wiring board 1 are both terminal parts 1.
1.2a are adhesively bonded in a state where they are electrically connected.

That is, as described above, this LSI bullet bonding method involves bonding the LSI bullet connection terminal portions 2a, 2a formed on one surface of the wiring board by mixing conductive particles 5, 5 in a heat-melting carbon paste. By forming the conductive particles 5.5 by printing agent A, the conductive particles 5.5 are present only in the LSI bullet connection terminal portions 2a, 2a, and the LSI bullet connection terminal portions 2a, 2a are formed at the LSI bullet connection portions on one side of the wiring board. This! The LSI bellet l-10 and the wiring board 1 are bonded together using an adhesive 6, and according to this connection method, the adjacent LSI
There is 1 between pellet 1 and connecting terminal part 2a, 2a! Since there is no conductive element, there is no short circuit between the adjacent terminal parts 2a, 2a and 11.11 of the wiring board 1 and the LSI pellet 10, and the conductivity in the bonding agent A is
．． Since it is possible to increase the number of 5ffi, LSI
By increasing the number of conductive particles 5.5 of the bullet connection terminal portions 2a, 2a, the arrangement board 1 and the terminal portions 2a, 2a of the LSI bullet 10 can be reliably electrically connected.

In addition, when forming the LSI bullet connection terminal parts 2a, 2a having a two-layer structure consisting of a conductive metal layer 3 and a carbon paste layer 4 mixed with conductive particles 5, 5, a conductive fully bent base is first formed on the substrate surface. After forming the LSI bellet connection terminal part and the wiring connected thereto, connect the LSI bellet 1.
-If you print adhesive on top of the VC terminal,
Positioning work is required to determine the printing position of the bonding agent, but in the above embodiment, the conductive metal layer 3 is formed on the a side of the film substrate over the entire surface, and a conductive metal layer 3 is formed in the carbon paste on top of the conductive metal layer 3. Bonding agent A mixed with particles 5,5,
Each terminal section 11.11 of LSI Beret Go O and the corresponding LSI Beren 1 to connection terminal section and wiring pattern were printed and dried, and this bonding agent was used as a mask to conductivity. By etching and removing unnecessary parts of the metal layer 3, a conductive metal layer 3 and a carbon paste mixed with conductive particles 5. Since the connecting terminal portions 2a, 2a are formed, positioning with respect to the conductive metal layer 3 is not necessary when printing the bonding agent A. Therefore, the LSI bullet connecting terminal portions 2a, 2a on the wiring board 1 surface are made conductive. Although it has a two-layer structure consisting of a composite layer 3 and a carbon base layer 4 mixed with conductive particles 5, 5, the distribution I! The substrate 1 can also be easily manufactured. In addition, in this embodiment, the layout of the wiring board 1!
! Since 2.2 is also formed by etching away unnecessary parts of the conductive metal layer 3 using the bonding agent A as a mask, the conductive particles 5.5 are distributed in a protruding state even on the surface of the wiring part. However, the conductive particles in this wiring part are 5.5
Since the protruding part is covered with carbon base l-, there is no risk of short circuiting even if it comes into contact with other electronic parts, and if the wiring part is insulated with insulating resin, it will not interfere with other electronic parts. Short circuits can be more reliably prevented.

In this embodiment, the wiring portion of the wiring board 1 also has a two-layer structure consisting of a conductive metal layer 3 and a carbon paste layer 4 mixed with conductive particles 5,5. It may have a two-layer structure consisting of a metal layer 3 and a carbon paste layer 4 that does not contain conductive particles 5.5,
In that case, LSI bullet connection terminal parts 2aa, 2a
Print bonding agent A, which is a mixture of conductive particles 5 and 5 in carbon paste, on the areas that will become wiring, and print carbon paste on the areas that will become wiring (however, in this case, the printing positions of bonding agent A and carbon paste should be ), or ``Alternatively, the openings corresponding to the wiring pattern of the mesh screen 7 shown in FIG. 1(a) may be passed through the conductive particles 5, 5. As a width without
It is sufficient that only the carbon paste of bonding agent A is printed on the surface of the film substrate 18.

In addition, in the above actual example, the LSI bullet connection terminal portion 2a
, 2a has a two-layer structure consisting of a conductive metal F13 and a carbon paste layer 4 mixed with conductive particles 5.5. It is also possible to have a single-layer structure consisting only of the carbon paste layer 4 mixed with carbon paste, and in that case, a solder paste having higher conductivity than the carbon paste may be used as the heat-melting conductive paste. Also, LSI
When the bellet connection terminal parts 2a, 2a have a two-layer structure, a heat-melting insulating paste (LSI Belen 1-
10 and distribution I! The same insulating adhesive 6 as the insulating adhesive 6 used to bond the substrate 1 may be used. Even in that case, the conductive particles 5.5 melt into the insulating base 1 during heat-pressing, and the conductive particles 5.5 bond to the underlying conductive layer. Since the conductive particles 5.5 are in contact with the metal layers 3, 3, electrical conduction can be ensured between the conductive particles 5.5 and the underlying conductive metal layer 3.3.

Furthermore, although the above embodiment describes the bonding of the LSI pellet 10, the present invention can be widely applied to bonding electronic components such as a liquid crystal display to a substrate in an LSI pellet pond.

FIG. 4 shows an embodiment in which the film substrate to which electronic parts are bonded has the function of, for example, a connector for connecting a liquid crystal display.One surface 16a of the film substrate 1G has a conductive Carbon paste layers 4, 4 mixed with particles 5.5 are printed in the form of parallel stripes.

In this case, the carbon paste layer 4 and the film substrate surface 16
A conductive metal layer having a higher conductivity than the carbon paste may be provided between the carbon paste layer 4 and the carbon paste layer 4, as in the embodiments shown in FIGS. 16a may be formed by printing. Further, on both edges of the film substrate surface 16a, insulating adhesives 6, 6 are printed and formed in a direction perpendicular to the striped carbon base layer 4.4, and this part is used for bonding electronic components. It is considered as a department. The method for forming the insulating adhesives 6, 6 is as described above, but for the film substrate 16 used as a connector, the insulating adhesives 6, 6 are dried in this state, and no contact force is applied at room temperature. To avoid having
It is convenient in actual use.

Thus, the film base 16 in which the layers and the insulating adhesives 6, 6 are formed on the carbon base 1 in this manner is used as follows. In FIG. 4, reference numeral 15 denotes a liquid crystal display, and electrode terminals 15a are arranged on one side edge of the liquid crystal display.

The stripes 15a are arranged at the same pitch as the striped carbon paste @4.4 formed on the film substrate 16. This liquid crystal display 15 has an insulating material printed on one end edge of the film substrate 16 so that each electrode terminal 15a corresponds to one end of each carbon paste 114.4 of the film substrate 16. The liquid crystal display 15 and the film substrate 16 are bonded by placing them on top of the adhesive 6 and applying heat and pressure. Further, the other end of the carbon paste layer 4.4 joins the other edge of the film substrate 16 (the part where the I8 edge adhesive 6 is printed) to the side edge of the wiring board 1 shown in FIG. By doing so, the film substrate 16 and the wiring board 1 are connected to the display body connecting terminal portions 2b, 2b arranged on the side edges of the wiring board 1, and the bonding between the film board 16 and the wiring board 1 is also performed by the method described above. In this case, the film substrate 16 has a carbon paste layer 4.4 and an insulating adhesive 6 formed thereon, and a display body connection terminal portion 2b formed on the upper surface of the wiring substrate 1.

2b, but this can be done by turning either the film board 16 or the wiring board 1 upside down, or by folding the wiring board joining edge of the film board 16 to the back side of the film board 16. It can be solved. Also, the arrangement I for joining the other edge of the film substrate 16! The J board 1 has its wiring Pi 12.2 and the display body connection terminal portion 2b.

2b may be formed of carbon paste FM4 mixed with conductive particles 5, 5, or may be formed of a conventional arrangement Li1.
12.2 and display connection terminal part 2b like the board
, 2b may be made of metal.

Note that in this embodiment, the film substrate 16 is used alone.

The film board 16 used as the connector is the same as the wiring board 1 shown in FIG.
It may be integrated with the wiring board 1 by extending a part of the film board 1a. Also in this embodiment, heat-melting bases 1 to II formed on the 16 surface of the film substrate
may be formed using a solder base 1- which has higher conductivity than carbon paste.

〔Effect of the invention〕

This invention involves printing a bonding agent containing conductive particles in a heat-melting paste on the board surface to form component connection terminals corresponding to the terminals of electronic components, and then drying the bonding agent. The electronic component is attached to the substrate surface by applying a heat-melting insulating adhesive to the component joint portion on the substrate surface, including the upper surface of the component connection terminal portion, and placing the electronic component thereon and heat-pressing it. Although it is a method of adhesively bonding electronic components to the board surface, it not only ensures conductive connection between the electronic components and the terminals on the board surface, but also prevents short circuits between adjacent terminals. This can be completely prevented, greatly improving reliability and yield.

[Brief explanation of drawings]

Figures 1 to 3 show an embodiment of this invention.
Figure 1 is an enlarged sectional view along the terminal section showing the process for joining the LSI bullet, Figure 2 is a perspective view of the LSI bullet and a wiring board coated with an insulating adhesive, and Figure 3 is the LSI bullet.
Arrange the beret! ! FIG. 3 is a cross-sectional view taken along the terminal portion in a state of being bonded to the substrate surface. FIG. 4 is a perspective view showing another embodiment of the present invention, showing a film substrate functioning as a connector with an insulating adhesive applied thereto. 1... Wiring board, 1a... Film board, 2...
Wiring, 2a... LSI bullet connection terminal section, 3...
Conductive metal layer, 4... carbon paste layer, 5...
Conductive particles, 6... Insulating adhesive, 7... Mesh screen, 8... Hard screen, A... Bonding agent, 10... LSI pellet, 11... Terminal part, 1
6... Film substrate, 16a... One side of the film substrate. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2

Claims (1)

[Claims] In an electronic component bonding method in which an electronic component is adhesively bonded to a substrate surface, a bonding agent containing conductive particles mixed in a heat-melting paste is printed on the substrate surface to connect the component corresponding to the terminal portion of the electronic component. After forming the terminal portion and drying the bonding agent, a heat-melting insulating adhesive is applied to the component bonding portion on the substrate surface including the upper surface of the component connection terminal portion, and then the A method for joining electronic components, which is characterized by stacking electronic components and bonding them under heat and pressure.