JPH098204A - Manufacture of semiconductor package - Google Patents

Abstract

PURPOSE: To improve the insulation reliability and quality stability of a semiconductor package by filling up through holes with solder grains from the sides opposite to the metallic pin inserting sides after the metallic pins are inserted into the holes and melting the solder grains by heating. CONSTITUTION: After a wiring board is coated with an electroless-plated copper film having a thickness of 15μm by dipping the wiring board in an electroless plating solution for additive for 1 hours, a conductor circuit, through holes 3, and a die pad 5 are formed. Then metallic pins 9 are inserted into the holes 3 from the side opposite to the surface of the wiring board on which the die pad 5 is formed and, after solder grains of 0.15mm in diameter are supplied to the surface carrying the die pad, the holes 3 are filled up with the solder grains composed of Pb and Sn mixed at a ratio of Pb/Sn=6/4 by vibrating the wiring board with ultrasonic waves. Then the pins 9 are fixed to the holes 3 by reflowing the solder grains by heating the solder grains at 250+20 deg.C with a nitrogen flow. No bubble nor solder icicle is observed from the solder in the holes 3. In addition, the amounts of the solder in the holes 3 become uniform and no solder is left on the lands 4 of the holes 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a so-called PGA (Pin Grid Array) semiconductor package having a metal pin as an external terminal, and in particular, it has excellent connection reliability between the metal pin and a through hole provided in a substrate. And a method for manufacturing a semiconductor package.

[0002]

2. Description of the Related Art The most general-purpose form of a semiconductor package is a so-called PGA form. This has a structure in which a metal pin, which is an external terminal, is fitted into a through hole, which is provided on an outer peripheral portion of the substrate and electrically connected to a semiconductor component mounted on the substrate, for solder connection.
Conventionally, when manufacturing such a PGA, a solder dip method, a heating and melting (reflow) method after printing a solder paste, and a cooling method have been adopted for the solder connection of the metal pin and the through hole. The solder dipping method is a method in which a portion of the PGA substrate that is not connected to the solder is covered with a solder resist, which is immersed in molten solder, and then cooled. The method (1) is a method in which a solder paste is filled in the gap between the through hole and the metal pin by screen printing or the like, and this is heated and melted and cooled to perform solder connection.

[0004]

However, in such a method, the amount of solder and the shape of the solder are not uniform in each through hole, and the solder is soaked in the molten solder and taken out to be cooled. Since the solder flows and becomes like a flicker, which short-circuits circuits that should not have electrical connection, insulation reliability is lowered. Further, in such a method, the amount of solder is non-uniform for each through hole, and the solder adheres thickly to the surface pad, which causes deterioration of mountability.

As described above, conventionally, regarding the method of soldering the metal pin and the through hole, a method excellent in insulation reliability and quality stability has not been proposed. An object of the present invention is to propose a method of manufacturing a semiconductor package having excellent insulation reliability and quality stability.

[0006]

According to the present invention, a through hole is formed in a substrate, a metal pin is inserted into the through hole, and then a solder connection is performed. , A method of manufacturing a semiconductor package, characterized in that a plurality of granular solders are filled into the through holes from the side opposite to the side into which the metal pins are fitted, and then heated and melted, and after forming the through holes in the substrate. In a method of manufacturing a semiconductor package in which a metal pin is fitted into the through hole and then soldered, one grain of spherical solder is inserted from the side opposite to the side where the metal pin is fitted after the metal pin is fitted into the through hole. Is placed in the through hole, and then heated and melted, and relates to a method for manufacturing a semiconductor package. The granular solder has a diameter of 0.10 to 0.20 mm. The diameter of the spherical solder is 0.4 to 1.0 mm.
It is. Granular or spherical solder and solder paste
It is different. The solder paste is a mixture of fine powder of solder and resin or solvent to increase the viscosity, and granular solder or spherical solder is a granular or spherical form of solder, and the resin for increasing the viscosity is Do not add.

[0007]

In the present invention, after the metal pin is inserted into the through hole provided in the board, the through hole is filled with a plurality of granular solders from the side opposite to the side in which the metal pin is inserted, and then heated and melted. It is necessary to. Unlike solder paste, granular solder does not contain resin or solvent, so it does not adhere to or remain on the substrate except for the particles that enter the through holes, and the solder remains on the pads of the through holes. There is no way to do soldering pickles. Furthermore, since the amount of granular solder filled in the through hole is determined by the gap formed by the through hole and the metal pin, the amount of solder becomes uniform. Further, in the conventional method, the solder is supplied from the land of the through hole to the inside of the through hole, but in the method of the present invention, since the solder is supplied to the land of the through hole from the inside of the through hole, excessive solder remains on the land. There is nothing to do. Since the through hole and the metal pin are plated with nickel-gold, the surface is covered with gold and has excellent wettability with solder, and the melted solder is transmitted to the surface covered with gold and supplied to the through hole. By heating and melting the filled granular solder (so-called reflow process), the metal pin and the through hole are connected.

The granular solder has a diameter of 0.10 to 0.10.
It is preferably 0.20 mm. The reason is 0.
This is because if it is less than 10 mm, the solder is clogged on the substrate surface (at a place other than PGA) and it is difficult to pour it. If it exceeds 0.20 mm, the filling amount is not stable for the most general through hole diameter of 0.55 mm. . In the present invention, after the metal pin is inserted into the through hole provided in the substrate, granular solder is supplied to the substrate surface opposite to the side where the metal pin is inserted, and then vibration such as ultrasonic waves is applied. It is desirable to fill the gap formed by the inner wall of the through hole and the metal pin with the granular solder and then heat and melt it. When the granular solder is supplied to the surface of the substrate opposite to the side where the metal pins are fitted, the granular solder rolls on the surface of the substrate and falls into the through holes. Furthermore, by applying ultrasonic vibration, excess granular solder existing on the substrate surface is removed, and the granular solder filled in the through holes is arranged so as to be the closest packed, so that the gap is efficiently filled. Bubbles are less likely to remain even when they are filled with heat and melted by heating, and a highly reliable connection becomes possible.

Another aspect of the present invention is a method of manufacturing a semiconductor package, in which a through hole is formed in a substrate, a metal pin is fitted into the through hole, and then solder connection is performed, and the metal pin is fitted into the through hole. After that, from the side opposite to the side into which the metal pin is fitted, one spherical solder is dropped into a space formed by the through hole and the metal pin and arranged, and then heated and melted. It is a manufacturing method. Spherical solder does not adhere to or remain on the board, except that it is placed in the void formed by the through hole and the metal pin, and solder remains on the through hole pad. , I can't do solder flicker. Further, since the amount of granular solder filled in the through hole is determined by the size of the spherical solder, the amount of solder becomes uniform and the amount can be easily adjusted.

Further, in the conventional method, the solder is supplied from the land of the through hole into the through hole, but in the method of the present invention, the solder is supplied from the inside of the through hole to the land of the through hole. No solder remains. Since the through-hole is nickel-gold plated, the surface is covered with gold and has excellent wettability with the solder, and the melted solder is transmitted through this gold-covered surface and supplied to the land. By heating and melting the filled granular solder (so-called reflow process), the metal pin and the through hole are connected.

The granular solder has a diameter of 0.4-1.
Desirably, it is 0 mm. This range is determined on the basis of a general-purpose through hole diameter of 0.55 mm, and if it is less than 0.4 mm, the amount of solder is reduced and 1.0
This is because the spherical solder cannot be fixed in the hole if it exceeds mm.

In the present invention, after the metal pin is fitted into the through hole formed in the substrate, an opening is provided at a position corresponding to the through hole on the surface of the substrate opposite to the side where the metal pin is fitted. It is desirable that the mask thus obtained is brought into close contact, then spherical solder is supplied, the spherical solder that has passed through the opening of the mask is placed in contact with the through hole or the metal pin, and then heated and melted. This is because the spherical solder drops once into the opening of the mask and then enters the through hole, so that the spherical solder can be reliably supplied and arranged in the through hole.

In the present invention, the method of forming the through holes in the substrate follows the conventional method. For example, in the additive method, the following steps are desirable. 1) An adhesive layer for electroless plating is formed on the substrate by applying an adhesive for electroless plating or laminating an adhesive film for electroless plating. The substrate may be a glass epoxy substrate, a ceramic substrate, copper or a heat dissipation substrate. Furthermore, the substrate may be an insulating substrate on which a conductor circuit is formed. 2) The surface of the adhesive for electroless plating is roughened by treating it with an acid or an oxidizing agent. 3) Drill holes for forming through holes. The drilling may be performed before the roughening treatment. 4) Add a catalyst for electroless plating. 5) Form a plating resist. The plating resist is formed by applying a photosensitive resin or laminating a photosensitive film, exposing and developing, and curing by heating. 6) Perform electroless plating to form through holes. At this time, a conductor circuit for connecting the through hole and the mounted semiconductor component is simultaneously formed. 7) Form a solder resist. The solder resist is a photosensitive resin containing a dye such as phthalocyanine green, and is coated and exposed and developed to form a solder resist layer.

As the adhesive for electroless plating, an adhesive in which a heat-resistant resin fine powder is dispersed in a resin matrix is desirable, and the heat-resistant resin powder has various shapes such as particle shape, hollow shape and crushed piece shape. In particular, in the case of particle shape, 1) particles having an average particle size of 10 μm or less, 2) heat-resistant resin powder having an average particle size of 2 μm or less are aggregated to have an average particle size of 2 to
Aggregated particles with a size of 10 μm, 3) Average particle size 2 to 10 μm
m, a mixture of a heat-resistant resin powder and a heat-resistant resin powder having an average particle size of 2 μm or less, 4) a heat-resistant resin powder having an average particle size of 2 μm or less or an average particle on the surface of the heat-resistant resin powder having an average particle size of 2 to 10 μm It is desirable to be selected from pseudo particles formed by adhering at least one kind of inorganic powder having a diameter of 2 μm or less. The reason for this is that if the average particle size exceeds 10 μm, the anchor becomes deep and it becomes impossible to form a so-called fine pattern of 100 μm or less, while the above 2) to 4).
The reason why the pseudo-particles are preferable is that a complex anchor can be formed and the peel strength can be improved. The heat-resistant resin matrix used is preferably epoxy resin, epoxy acrylate, or the like. As the heat resistant resin particles, an amino resin such as an epoxy resin or a melanin resin is desirable.

In the present invention, the diameter of the through hole is preferably ± 0.2 mm of the PGA pin diameter. In the present invention, it is possible to supply solder for metal pins at the same time as flip-chip mounting. The reason for this is that since flip-chip mounting is soldered, simultaneous reflow is possible. The present invention will be described in more detail with reference to examples. The numbers in the examples are the numbers in the drawings.

[0016]

【Example】

(Example 1) (1) According to a conventional method, a wiring board 1 having three layers of conductor circuits on both surfaces of a glass epoxy substrate was prepared (Fig. 1). (2) Epoxy resin particles (Toray, average particle size 3.9 μm)
While stirring in a Henschel mixer into an alumina particle suspension obtained by dispersing 200 g in 5 l of acetone,
Epoxy resin (made by Mitsui Petrochemical) for 1 liter of acetone
300 g of an epoxy resin powder (manufactured by Toray Co., Ltd., average particle size: 0.5 μm) was dispersed in an acetone solution in which 30 g of was dissolved to obtain a suspension of the epoxy powder. After the attachment, the acetone was removed and then heated to 150 ° C. to prepare pseudo particles. This pseudo particle has an average particle size of about 4.3 μm,
75% by weight was in the range of ± 2 μm centered on the average particle size.

(3) of a cresol novolac type epoxy resin (made by Nippon Kayaku, molecular weight 2500) dissolved in DMDG
70 parts by weight of 25% acrylate, 30 parts by weight of polyether sulfone (PES), 4 parts by weight of imidazole curing agent (manufactured by Shikoku Kasei, product name: 2E4MZ-CN), and caprolactone modified tris (acryloxy) as a photosensitive monomer. ethyl)
Isocyanurate (manufactured by Toagosei, trade name; Aronix M325) 10 parts by weight, benzophenone as a photoinitiator (manufactured by Kanto Kagaku) 5 parts by weight, photosensitizer Michler ketone (manufactured by Kanto Kagaku) 0.5 parts by weight, and further After mixing 40 parts by weight of the epoxy resin pseudo particles prepared in (2) above with the mixture, the mixture was mixed while adding NMP, and the viscosity was adjusted to 2000 CPS with a homodisper stirrer, followed by three rolls. The mixture was kneaded to obtain a photosensitive adhesive solution. (4) This photosensitive adhesive solution was applied onto the wiring board prepared in (1) above using a roll coater, left standing for 20 minutes in a horizontal state, and then dried at 60 ° C.

(5) A photomask film having a 100 μmφ black circle printed thereon was brought into close contact with the wiring board subjected to the treatment of (4) above, and exposed with an ultrahigh pressure mercury lamp of 500 mj / cm ² .
By spray developing this with DMDG (diethylene glycol dimethyl ether) solution, 10
An opening to be a via hole of 0 μmφ was formed (Fig. 1
b). In addition, the wiring board is installed with an ultra-high pressure mercury lamp for about 3000
Exposure at mj / cm ² at 100 ° C for 1 hour, then 150 ° C for 5 hours
By heat treatment for a period of time, a resin interlayer adhesive layer 2 having a thickness of 50 μm and having an opening excellent in dimensional accuracy, which corresponds to a photomask film, was formed. (6) The wiring board that has been subjected to the treatment of (5) above has a pH of 13
Adjusted to potassium permanganate (KMnO ₄ , 60 g / l)
The surface of the inter-layer resin insulation layer is roughened by immersing it in 70 ° C for 15 minutes to form a roughened surface 4, and then a neutralizing solution (made by Shipley).
It was immersed in water and washed with water. (7) A palladium catalyst (manufactured by Shipley) was applied to the substrate having the roughened surface of the adhesive layer to activate the surface of the adhesive layer 3.

(8) Cresol novolac type epoxy resin (manufactured by Nippon Kayaku, trade name EOCN-103) dissolved in DMDG (dimethyl glycol dimethyl ether)
S) sensitized oligomer (molecular weight 4000) in which 25% of epoxy group is acrylated, PES (molecular weight 170)
00), imidazole-based curing agent (Shikoku Kasei product name
2 PMHZ-PW), acrylated isocyanate which is a photosensitive monomer (trade name Aronix manufactured by Toagosei)
M215), benzophenone (manufactured by Kanto Chemical Co., Inc.) as a photoinitiator, and Michler ketone (sensitized by Kanto Chemical Co., Inc.) as a photosensitizer,
After mixing with the following composition using NMP, the viscosity was adjusted to 3000 cps with a homodisper stirrer, followed by kneading with a triple roll to obtain a liquid resist. Resin composition: Photosensitive epoxy / PES / M325 / BP
/MK/imidazole=70/30/10/5/0.5
/ 5 (9) This liquid resist was applied onto the resin insulating layer of (7) above using a roll coater and dried at 60 ° C. to form a resist layer having a thickness of about 30 μm (FIG. 2).

(10) A mask film on which a conductor circuit pattern of L / S = 50/50 is drawn is brought into close contact with the wiring board subjected to the treatment of (9) above, and an ultrahigh pressure mercury lamp of 1000 m
Exposure was at J / cm ² . This was spray-developed with triethylene glycol dimethyl ether (DMDG) to form a plating resist with a missing conductor circuit pattern on the wiring board. Further, it was exposed with an ultrahigh pressure mercury lamp at 6000 mJ / cm ² , and heat-treated at 100 ° C. for 1 hour and then at 150 ° C. for 3 hours. This plating resist has through holes 3 (diameter 0.6 m
m), for patterning and forming the die pad 5. (11) The wiring board of (10) is immersed in an electroless plating solution for additive having the composition shown below for 11 hours, and electroless copper plating having a plating film thickness of 15 μm is performed to form a conductor circuit,
Through holes 3 and die pad 5 were formed.

(12) Cresol novolak type epoxy resin dissolved in DMDG Nippon Kayaku product name EOCN
-103S) 25% acrylated photosensitive oligomer of epoxy group (molecular weight 4000), PES (molecular weight
17000), imidazole-based curing agent (Shikoku Kasei product name 2P4MHZ-PW), photosensitive monomer acrylated isocyanate (Toagosei product name Aronix M215), benzophenone as photoinitiator, photosensitizer Michler (Kanto). Chemistry) and a colorant (phthalocyanine green) were mixed with NMP with the following composition, the viscosity was adjusted to 2000 cps with a homodisper stirrer, and then the mixture was kneaded with three rolls to obtain a liquid solder resist. Resin composition: Photosensitive epoxy / PES / M325 / BP /
MK / imidazole = 70/30/10/5 / 0.5 /
5 (13) This liquid solder resist was applied onto the wiring board using a roll coater and dried at 60 ° C. to form a solder resist layer having a thickness of 20 μm.

(14) A mask film having a pattern in which a part of the die pad is hidden is brought into close contact with the wiring board subjected to the treatment of (13), and exposed. This was spray-developed with diethylene glycol diethyl ether (DMDG) to form an opening 15 so that the roughened surface formed on the metal pad was exposed. Further, it was exposed with an ultrahigh pressure mercury lamp at 3000 mj / cm ² , and the exposure was performed at 100 ° C.
After that, heat treatment was performed for 3 hours at 150 ° C. to obtain a solder resist 6 (FIG. 2). (15) Nickel-gold plating was applied to the through holes according to a conventional method (not shown). (16) Insert the metal pin 9 on the surface opposite to the surface on which the die pad 5 is formed (FIG. 3), and supply the granular solder 10 having a diameter of 0.15 mm to the surface on which the die pad 5 is formed (FIG. 4).
After that, ultrasonic vibration was performed to fill the Pb / Sn = 6/4 granular solder (FIG. 5 and an enlarged view are shown in FIG. 7).

(17) Then 250 ± 20 with nitrogen flow
Reheat by heating at ℃ and re-flow metal pin 9 through hole 3
(FIG. 6 and FIG. 12 as an enlarged view).
No bubbles were observed in the solder 11 in the through holes, and solder icicles were not observed. Further, the amount of solder in each through hole was uniform. No solder remained on the land 4 of the through hole 3.

Example 2 (1) The steps (1) to (15) of Example 1 were carried out. (2) A mask provided with an opening having a diameter of about 0.7 mm at the position of the through hole 3 was brought into close contact with the substrate. (3) Pb / Sn = 9/1 spherical solder with a radius of 0.6 mm was supplied to the mask surface (FIG. 8), and the spherical solder was arranged in the through hole (FIG. 9 and an enlarged view are shown in FIG. 11). To). (4) Then, it was heated at 250 ° C. with a nitrogen flow and reflowed to fix the metal pin 9 to the through hole 3 (FIG. 10 and FIG. 12 as an enlarged view). No bubbles were observed in the solder 11 in the through holes, and solder icicles were not observed. Further, the amount of solder in each through hole was uniform. No solder remained on the land 4 of the through hole 3.

Comparative Example 1 (1) A printed wiring board was formed by the steps (1) to (15) of the example. (2) After dipping the printed wiring board into a solder bath in which Pb / Sn = 9/1 solder is melted at 250 ° C., take out the printed wiring board and cool it to room temperature to fix the metal pin 9 to the through hole 3. (FIG. 13 is shown as an enlarged view). In the obtained product, the solder remained on the land 4 of the through hole and the metal pin 9, and the amount of solder in each through hole varied. Further, solder protrusions (solder icicles) were found at the tips of the metal pins.

Comparative Example 2 (1) A printed wiring board was formed by the steps (1) to (15) of the example. (2) Solder cream of Pb / Sn = 6/4 was printed on the land of the through hole, then heated at 235 ° C. and reflowed to fix the metal pin 9 to the through hole 3 (see FIG. 14 as an enlarged view). ). In the obtained product, the solder remained on the land 4 of the through hole, and the amount of solder in each through hole varied.

Comparative Example 3 This example is basically the same as Example 1, but the grain size of the granular solder was 0.05 mm. At this time, solder was attached to pads other than the PGA land. (Comparative Example 4) This example is basically the same as Example 1, but the grain size of the granular solder was 0.25 mm. At this time, there were variations in the filling amount.

Comparative Example 5 This example is basically the same as Example 2, but the grain size of the granular solder was 0.3 mm. At this time, two spherical solder particles entered the through holes, and the amount of filling varied. Comparative Example 6 This example is basically the same as the example 2, but the grain size of the granular solder was 1.5 mm. At this time, the amount of solder was too large, the spherical solder was not fixed, and the workability deteriorated.

As described above, in the printed wiring board of the present invention, solder does not adhere to the metal pins, there is no variation in the amount of solder, solder flicker is not observed, and the connection is highly reliable. Is possible.

[Brief description of drawings]

FIG. 1 is a first substrate according to a manufacturing method of the present invention.

FIG. 2 is a substrate on which a through hole is formed according to the manufacturing method of the present invention.

FIG. 3 is a substrate in which metal pins are fitted in through holes according to the manufacturing method of the present invention.

FIG. 4 Supply of granular solder according to the manufacturing method of the present invention

FIG. 5 is a substrate filled with granular solder according to the manufacturing method of the present invention.

FIG. 6 is a substrate in a state where the granular solder according to the manufacturing method of the present invention is reflowed.

FIG. 7 is an enlarged cross-sectional view of a substrate filled with granular solder.

FIG. 8 is a substrate in a state where the spherical solder according to the manufacturing method of the present invention is reflowed.

FIG. 9 is a substrate filled with spherical solder according to the manufacturing method of the present invention.

FIG. 10 is a substrate in a state where the spherical solder according to the manufacturing method of the present invention is reflowed.

FIG. 11 is an enlarged sectional view of a substrate filled with spherical solder.

FIG. 12 is an enlarged sectional view of the substrate after reflow.

FIG. 13 is an enlarged sectional view of a board obtained by a solder dip method.

FIG. 14 is an enlarged sectional view of a substrate obtained by a screen printing method.

[Explanation of symbols]

 1 Glass Epoxy Substrate 2 Conductor Circuit 3 Through Hole 4 Through Hole Land 5 Die Pad 6 Solder Resist 7 Plating Resist 8 Adhesive Layer 9 Metal Pin 10 Granular Solder 11 Solder 12 Mask 13 Spherical Solder

Claims (6)

[Claims] 1. In a method of manufacturing a semiconductor package, wherein a through hole is formed in a substrate, a metal pin is fitted into the through hole, and then solder connection is performed. After the metal pin is fitted into the through hole, the metal pin is fitted. A method for manufacturing a semiconductor package, characterized in that a plurality of granular solders are filled in the through holes from the side opposite to the side where the heat treatment is performed, and then the solder is heated and melted. 2. The granular solder has a diameter of 0.1 to 10.
The method for manufacturing a semiconductor package according to claim 1, wherein the size is 0.2 mm. 3. After inserting a metal pin into the through hole, granular solder is supplied to the surface of the substrate opposite to the side where the metal pin is inserted, and then vibration is applied to the inner wall of the through hole and the metal pin. The method for manufacturing a semiconductor package according to claim 1, wherein the gap formed by is filled with the granular solder and then heated and melted. 4. In a method of manufacturing a semiconductor package, wherein a through hole is formed in a substrate, a metal pin is fitted into the through hole, and then solder connection is performed. After the metal pin is fitted into the through hole, the metal pin is fitted. A method of manufacturing a semiconductor package, wherein one particle of spherical solder is placed in the through hole from the side opposite to the side and then heated and melted. 5. The diameter of the spherical solder is 0.4 to 1.0.
The method for manufacturing a semiconductor package according to claim 4, wherein the size is mm. 6. After inserting a metal pin into the through hole, the substrate surface opposite to the side into which the metal pin is inserted,
A mask having an opening provided at a position corresponding to the through hole is brought into close contact, spherical solder is supplied, spherical solder that has passed through the opening of the mask is placed in the through hole, and then heated and melted. The method for manufacturing a semiconductor package according to claim 4, wherein