JP4067027B2 - Printed wiring board and manufacturing method thereof - Google Patents

Description

  The present invention relates to a printed wiring board provided with a through hole penetrating an insulating substrate, and a method for manufacturing the same, and more particularly to a method of filling a through hole with a filler.

For example, a ball grid type printed wiring board is provided with through-holes for electrical conduction of each pattern circuit provided on the front side surface and the back side surface or for heat dissipation.
As shown in FIG. 16, the through hole 90 is provided through the insulating substrate 9 constituting the printed wiring board. A metal plating film 93 is applied to the inner wall of the through hole 90.

  The through hole 90 is filled with a filler 91 using an epoxy resin. The filler 91 prevents the flux, solder cleaning solution, and the like from seeping out through the through hole 90 when soldering the printed wiring board to the motherboard, and the pattern circuit 961 provided on the front side surface of the insulating substrate 9 or the semiconductor chip 5. Or it plays the role which prevents the contamination of the die pad 963 which mounts this.

  However, in the printed wiring board, a peeling portion 991 may be generated between the metal plating film 93 and the filler 91 in the through hole 90 depending on the temperature when soldering the printed wiring board on the mother board ( FIG. 16). When the printed wiring board is used, moisture may enter from the peeling portion 991 and accumulate as moisture 995 between the insulating substrate 9 and the adhesive 990 in some cases. The moisture 995 may corrode the pattern circuit 961, the semiconductor chip 5, or the die pad 963 provided on the front side surface of the insulating substrate 9.

  Further, when the printed wiring board is soldered to the mother board as described above, the heat causes the moisture 995 to be rapidly heated, and a peeled portion is formed between the insulating substrate 9 and the semiconductor chip 5 as shown in FIG. 992 may occur. Further, the pattern circuit 961, the semiconductor chip 5, and the die pad 963 may be damaged.

  In view of such conventional problems, the present invention does not cause separation between the metal plating film in the through hole and the filler filled in the through hole, and can prevent moisture from entering. A printed wiring board and a manufacturing method thereof are to be provided.

In the first invention, a through-hole penetrating the insulating substrate is formed in the insulating substrate,
Next, a metal plating film is applied to the surface of the insulating substrate and the inner wall of the through hole, and a roughened surface layer is formed on the surface of the metal plating film,
Next, the filler is supplied to the inside of the through hole and the periphery of the opening to be cured,
Next, the filler and the roughened surface layer protruding from the surface of the insulating substrate are polished and made smooth ,
Then, obtained by forming a pattern circuit on the surface of the insulating substrate,
In the printed wiring board, a semiconductor chip is mounted on the through hole through a resin layer made of an epoxy resin containing a die attach resin, an epoxy resin, or a filler. .

  The surface of the metal plating film can be subjected to chemical surface treatment to form a roughened surface layer. Examples of the chemical surface treatment include a method of performing only blackening treatment, a method of sequentially performing blackening treatment and blackening reduction treatment, a method of sequentially performing blackening treatment, blackening reduction treatment, and acid treatment.

  As a method for performing only the blackening treatment, for example, the insulating substrate is immersed in a blackening treatment solution in which sodium chlorite, trisodium phosphate, sodium hydroxide, or the like is dissolved in water. Thereby, the acicular crystal | crystallization produces | generates on the surface of a metal plating film. This crystal constitutes a roughened surface layer in the through hole and on the surface of the insulating substrate.

  As a method of sequentially performing the blackening treatment and the blackening reduction treatment, for example, the first reduction in which the insulating substrate is immersed in the blackening treatment solution and then sodium borohydride, sodium hydroxide, etc. are dissolved in water. The insulating substrate is immersed in a processing solution. Furthermore, this is immersed in the 2nd reduction process liquid which melt | dissolved sodium hydroxide, formaldehyde, methanol, etc. in water. Thereby, the acicular crystal | crystallization produces | generates on the surface of a metal plating film, and this crystal | crystallization is reduce | restored.

  As a method for sequentially performing the blackening treatment, the blackening reduction treatment, and the acid treatment, for example, the insulating substrate is immersed in the blackening treatment solution and the reduction treatment solution in order, and then the sulfuric acid for acid treatment is used. Immerse in an acid treatment solution. Thereby, the acicular crystal | crystallization produces | generates on the surface of a metal plating film | membrane, and after this crystal | crystallization is reduced once, it is oxidized.

  Next, the inside of the through hole forming the roughened surface layer and the periphery of the opening are filled with a filler and cured. Next, the filler protruding from the surface of the insulating substrate is polished and removed together with the roughened surface layer of the metal plating film on the surface of the insulating substrate using a buff, a brush or the like. Thereby, the surface of the said metal plating film and a filler becomes smooth, and the whole surface of an insulated substrate becomes a smooth surface. Next, a pattern circuit is formed on the surface of the smooth insulating substrate.

  The filler is an electrically insulating material or a conductive material. The electrical insulating material is, for example, one or more synthetic resins selected from epoxy resins and polyimide resins. The said metal plating film consists of 1 type, or 2 or more types chosen from copper, nickel, and gold | metal | money. On the other hand, examples of the conductive material include carbon paste. As the insulating substrate, for example, a glass / epoxy substrate, a glass / polyimide substrate, a glass maleimide triazine substrate or the like is used.

The through holes are used to electrically connect the pattern circuits provided on the front and back sides of the insulating substrate. The through hole can also be used as a heat radiating hole for dissipating heat from the semiconductor chip or the pattern circuit.
For example, a semiconductor chip can be mounted on the printed wiring board. The printed wiring board is mounted on a separate mother board.
Examples of the printed wiring board include a ball grid array and a pin grid array.

(Function and effect)
In the printed wiring board according to the present invention, a metal plating film is formed on the inner wall of the through hole, and a roughened surface layer is formed on the surface of the metal plating film. The through hole is filled with a filler. The filler adheres to the inner wall of the through hole due to the unevenness of the roughened surface layer. Therefore, even if it receives a thermal shock, the filler is not peeled off from the inner wall of the through hole. Therefore, it is possible to prevent moisture from entering from the through hole.

  In the present invention, the filler is supplied not only to the inside of the through hole but also to the periphery of the opening. Therefore, even if the filler shrinks when the filler is cured, the entire inside of the through hole can be filled with the filler.

  In addition, although the surface of the metal plating on the surface of the insulating substrate becomes a roughened surface layer, this is polished and removed to make a uniform smooth surface. Therefore, even when the metal plating surface is further covered with a plating film, a plating film having a uniform thickness can be formed. Therefore, a smooth pattern circuit having a uniform layer thickness can be formed on the surface of the insulating substrate.

  Therefore, even when this pattern circuit is used as a die pad and an electronic component such as a semiconductor chip is mounted on the die pad using an adhesive, the pattern circuit and the adhesive can be brought into close contact with each other. Therefore, even when subjected to a thermal shock, the adhesive does not peel off from the circuit pattern, and moisture does not enter. As a result, damage to electronic components and pattern circuits can be suppressed.

  According to the present invention, there is provided a printed wiring board capable of preventing moisture from entering without causing separation between the metal plating film in the through hole and the filler filled in the through hole. can do.

The second invention comprises a step of drilling a through-hole penetrating the insulating substrate in the insulating substrate;
Next, a step of applying a metal plating film to the surface of the insulating substrate and the inner wall of the through hole;
A step of forming a roughened surface layer on the surface of the metal plating film;
Next, filling the inside of the through hole and the periphery of the opening with a filler made of an electrically insulating material;
Next, a step of polishing and removing the filler and the roughened surface layer protruding from the surface of the insulating substrate to make a smooth surface ;
Then, forming a pattern circuit on the surface of the insulating substrate,
In the printed wiring board manufacturing method, the semiconductor chip is mounted thereon via a die attach resin, an epoxy resin, or an epoxy resin layer containing a filler. (Claim 3).

  In the first invention (invention 1), the roughened surface layer preferably has a needle-like surface (invention 2).

Example 1
The printed wiring board concerning the Example of this invention is demonstrated using FIGS.
As shown in FIGS. 1 and 2, the printed wiring board 10 of this example is provided with a through-hole 90 provided through the insulating substrate 9. The inner wall of the through hole 90 is covered with the metal plating film 3 having the roughened surface layer 30. The inside of the through hole 90 is filled with an electrical insulating material 1 as a filler.

A pattern circuit 61 and a die pad 63 for mounting a semiconductor chip are provided on the front side surface of the insulating substrate 9. A pattern circuit 62 and a heat radiating pad 64 are provided on the back side surface of the insulating substrate 9.
The die pad 63 and the heat radiating pad 64 are connected by the through hole 90 provided in the substantially central portion of the insulating substrate 9. As shown in FIG. 2, the pattern circuits 61 and 62 on the front side surface and the back side surface are connected by the through hole 90 provided in the peripheral portion of the insulating substrate 9.

The semiconductor chip 5 is mounted on the die pad 63 by an adhesive 59. The semiconductor chip 5 is connected to the bonding pad 610 at the tip of the pattern circuit 61 by a wire 50. The semiconductor chip 5 and the wire 50 are sealed with a resin 55. The adhesive 59 is a die attach resin, an epoxy resin, an epoxy resin containing a filler, or the like.
The printed wiring board 10 of this example is a system in which the semiconductor chip 5 and the pattern circuit 61 are connected by a wire 50.

  Further, a pattern circuit 62 and a heat dissipation pad 64 are provided on the back side surface of the insulating substrate 9. On the pattern circuit 62, a plurality of pads 620 for bonding with the pads 82 of the mother board 8 by the solder 81 are provided.

Next, the manufacturing method of the said printed wiring board is demonstrated using FIGS.
First, as shown in FIG. 3, an insulating substrate 9 having a front side surface and a back side surface coated with copper foil 2 is prepared. Next, as shown in FIG. 4, a through hole 90 penetrating the insulating substrate 9 is formed. Next, as shown in FIG. 5, the metal plating film 3 is applied to the surface of the insulating substrate 9 and the inner wall of the through hole 90. The metal plating film 3 is copper.

Next, as shown in FIG. 6, a roughened surface layer 30 is formed on the surface of the metal plating film 3 by chemical surface treatment. The chemical surface treatment is performed by a blackening treatment.
The blackening treatment is performed by immersing the insulating substrate 9 in the following blackening treatment liquid for 0.3 to 15 minutes. By this blackening treatment, copper needle-like crystals are formed on the surface of the metal plating film 3.

(1) Blackening solution / component (concentration in water)
Sodium chlorite. . . . . . . 20-70 g / liter,
Trisodium phosphate 12 water. . . . 10-30 g / liter,
Sodium hydroxide. . . . . . . . 10-30 g / liter,
·temperature. . . . . . . . 70-98 ° C,

Next, as shown in FIG. 7, the electrical insulating material 1 made of an epoxy resin is supplied into the through hole 90 and the periphery of the opening by means of screen printing or the like. At this time, the electrical insulating material 1 is projected from the surface of the insulating substrate 9. Next, the electrical insulating material 1 is heated to 150 ° C. and cured.
Next, as shown in FIG. 8, the electrically insulating material 1 and the roughened surface layer 30 protruding on the surface of the insulating substrate 9 are polished and removed by buffing to obtain a smooth surface.

Next, as shown in FIGS. 9 to 13, a pattern circuit, a die pad, and a heat dissipation pad are formed on the surface of the insulating substrate 9 by an etching resist method.
That is, first, as shown in FIG. 9, a resist film 71 having a desired pattern is coated on the front side surface and the back side surface of the insulating substrate 9. Next, unnecessary portions of the copper foil 2 and the metal plating film 3 are removed from the insulating substrate 9 by etching. Next, the resist film 71 is peeled off.

  Thereby, as shown in FIG. 10, the pattern circuit 61, the bonding pad 610, and the die pad 63 are formed on the front side surface of the insulating substrate 9. A pattern circuit 62 and a heat dissipation pad 64 are formed on the back side surface of the insulating substrate 9.

  Next, as shown in FIG. 11, the metal plating film 3 of the pattern forming portion is partially exposed on the front side surface and the back side surface of the insulating substrate 9, and the solder resist film 72 is covered. Next, as shown in FIG. 12, the Ni / Au plating film 4 is partially coated on the surface of the metal plating film 3 by plating.

  Thereby, as shown in FIG. 13, the die pad 63 and the bonding pad 610 are covered with the Ni / Au plating film 4. In addition, a pad 620 for bonding to the mother board is formed on the back side surface of the insulating substrate 9. Thereby, the printed wiring board 10 is obtained.

  The semiconductor chip 5 is mounted on the die pad 63 of the printed wiring board 10 by using an adhesive 59 as shown in FIG. The semiconductor chip 5 is electrically connected to the bonding pad 610 by the wire 50. The semiconductor chip 5 and the wire 50 are sealed with a resin 55.

  As shown in FIG. 1, the pads 620 on the back side surface of the printed wiring board 10 are disposed on the pads 82 of the mother board 8 via ball-shaped solder 81. This is heated to solder the pads 620 of the printed wiring board and the pads 82 of the motherboard 8.

Next, the function and effect of this example will be described.
In the printed wiring board according to this example, as shown in FIGS. 6 and 7, the surface of the metal plating film 3 formed on the inner wall of the through hole 90 is subjected to a chemical surface treatment to form a roughened surface layer 30. is doing. Therefore, the electrical insulating material 1 is in close contact with the inner wall of the through hole 90 due to the unevenness of the roughened surface layer 30.
Therefore, even if it receives a thermal shock, the electrically insulating material 1 is not peeled off from the inner wall of the through hole 90. Therefore, it is possible to prevent moisture from entering from the through hole 90.

  Therefore, even when the printed wiring board is mounted on the mother board by soldering, peeling does not occur between the metal plating film in the through hole and the electrically insulating material due to the melting temperature of the solder.

  In addition, the electrical insulating material 1 is supplied not only to the inside of the through hole 90 but also to the periphery of the opening. Therefore, even if the electrical insulating material 1 contracts when the electrical insulating material 1 is cured, the entire interior of the through hole 90 can be filled with the electrical insulating material 1.

In addition, a roughened surface layer is formed on the metal plating 3 on the surface of the insulating substrate 9, but this is then polished to obtain a uniform smooth surface. Therefore, even when the surface of the metal plating 3 is further covered with a plating film, a plating film having a uniform thickness can be formed.
Therefore, the pattern circuit 61 and the die pad 63 having a smooth and uniform layer thickness can be formed on the surface of the insulating substrate 9.

  Therefore, when the semiconductor chip 5 is mounted on the die pad 63 using the adhesive 59, the die pad 63 and the adhesive 59 can be brought into close contact with each other. Therefore, even when subjected to a thermal shock, the adhesive 59 does not peel off from the die pad 63, and moisture does not enter. As a result, damage to the semiconductor chip 5, the die pad 63, and the pattern circuit 61 can be suppressed.

  In the above description, the example in which the connection between the semiconductor chip 5 and the wiring pattern 61 on the insulating substrate 9 is made by the wire 50 via the bonding pad 610 is shown. However, the connection between the semiconductor chip 5 and the wiring pattern 61 can also be performed by a method in which a solder bump 500 is provided on the bonding pad 610 of the wiring pattern 61 and connected to the semiconductor chip 5 as shown in FIG.

(Example 2)
In this example, blackening treatment and blackening reduction treatment were sequentially performed as the chemical surface treatment to form a roughened surface layer on the surface of the metal plating film.
That is, first, the blackening process shown in Example 1 was performed. Next, the insulating substrate was immersed in the following first reduction treatment liquid and second reduction treatment liquid in order to perform blackening reduction treatment. The immersion time in the first reduction treatment liquid and the immersion time in the second reduction treatment liquid are 0.1 to 15 minutes.

(1) First reduction treatment liquid / component Sodium borohydride. . . . . 0.1 to 5.0 g / liter,
Sodium hydroxide. . . . . . . 0.1 to 5.0 g / liter,
·temperature. . . . . . . . . . . . . 30-60 ° C,

(2) Second reducing solution / component Sodium hydroxide. . . . . . . 1.0-10 g / liter,
Formaldehyde. . . . . . . 1.0-20 g / liter,
methanol. . . . . . . . . . 1.0-30 g / liter,
·temperature. . . . . . . . . . . . . 30-60 ° C,

By the blackening reduction treatment, reduced copper needle crystals are generated on the surface of the metal plating film.
Others are the same as in the first embodiment. In this example, since the said process is performed, it is more excellent in the point of an acid-resistant improvement than the case of Example 1. FIG. In addition, also in this example, the same effect as Example 1 can be acquired.

(Example 3)
In this example, blackening treatment, blackening reduction, and acid treatment were sequentially performed as chemical surface treatments to form a roughened surface layer on the surface of the metal plating film.
That is, in performing the process of this example, first, the blackening process shown in Example 1 was performed, and then the blackening reduction process shown in Example 2 was performed. Subsequently, the said insulating substrate was immersed in the acid treatment liquid which consists of the following components. The immersion time in the acid treatment solution is 0.1 to 10 minutes.

(1) Acid treatment solution / component Sulfuric acid. . . . . 30-300 g / liter,
·temperature. . . . . . 5-40 ° C,

By the chemical surface treatment, oxidized copper needle crystals were formed on the surface of the metal plating film.
Others are the same as in the second embodiment. Also in this example, the same effect as that of the second embodiment can be obtained.

Sectional drawing of the state which mounted the printed wiring board of Example 1 on the motherboard. FIG. 3 is an explanatory diagram illustrating a front side surface of the printed wiring board according to the first embodiment. In the manufacturing method of the printed wiring board of Example 1, sectional drawing of the insulated substrate which coat | covered the copper foil on the surface. FIG. 4 is a cross-sectional view of an insulating substrate in which a through hole is formed following FIG. 3. Sectional drawing of the insulated substrate which gave the metal plating film following FIG. FIG. 6 is a cross-sectional view of an insulating substrate on which a roughened surface layer is formed, following FIG. 5. FIG. 7 is a cross-sectional view of an insulating substrate in which a through-hole is filled with an electrically insulating material, following FIG. 6. FIG. 8 is a cross-sectional view of an insulating substrate whose surface is polished following FIG. 7. FIG. 9 is a cross-sectional view of an insulating substrate coated with a resist film, following FIG. 8. FIG. 10 is a cross-sectional view of an insulating substrate on which a pattern is formed, following FIG. 9. FIG. 11 is a cross-sectional view of an insulating substrate coated with a solder resist film, following FIG. 10. Sectional drawing of the insulated substrate which gave the Ni / Au plating film following FIG. FIG. 13 is a cross-sectional view of the insulating substrate after removing the solder resist film, following FIG. 12. Sectional drawing of the printed wiring board carrying a semiconductor chip. Sectional drawing of the printed wiring board of Example 1 electrically connected with the semiconductor chip using the bump. Explanatory drawing which shows the internal state of the through hole in a prior art example. Explanatory drawing which shows the internal state of a through hole at the time of receiving the thermal shock in a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrical insulating material 10 Printed wiring board 2 Copper foil 3 Metal plating film 30 Roughening surface layer 4 Ni / Au plating film 5 Semiconductor chip 61, 62 Pattern circuit 63 Die pad 64 Heat radiation pad 8 Motherboard 9 Insulating substrate 90 Through hole

Claims (3)

Drilling a through-hole through the insulating substrate in the insulating substrate,
Next, a metal plating film is applied to the surface of the insulating substrate and the inner wall of the through hole, and a roughened surface layer is formed on the surface of the metal plating film,
Next, the filler is supplied to the inside of the through hole and the periphery of the opening to be cured,
Next, the filler and the roughened surface layer protruding from the surface of the insulating substrate are polished and made smooth ,
Then, obtained by forming a pattern circuit on the surface of the insulating substrate,
A printed wiring board, wherein a semiconductor chip is mounted on the through hole via a resin layer made of an epoxy resin containing a die attach resin, an epoxy resin, or a filler.   The printed wiring board according to claim 1, wherein the roughened surface layer has a needle-like surface. Drilling a through hole through the insulating substrate in the insulating substrate;
Next, a step of applying a metal plating film to the surface of the insulating substrate and the inner wall of the through hole;
A step of forming a roughened surface layer on the surface of the metal plating film;
Next, filling the inside of the through hole and the periphery of the opening with a filler made of an electrically insulating material;
Next, a step of polishing and removing the filler and the roughened surface layer protruding from the surface of the insulating substrate to make a smooth surface ;
Then, forming a pattern circuit on the surface of the insulating substrate,
A method of manufacturing a printed wiring board, wherein a semiconductor chip is mounted on the through hole via a layer of an epoxy resin containing a die attach resin, an epoxy resin, or a filler.

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