JP2010225716A - Wiring board, method of manufacturing the same, and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring board which forms a thin protective coating capable of preventing outflow of solder in order to shorten the distance between an electric component and the wiring board as much as possible, and to provide a method for mounting an electric component on the wiring board. <P>SOLUTION: In the wiring board 100 provided, in the uppermost layer, with a metal wiring pattern 11 having an electrode, an electrically insulating protective coating 2 is formed to cover the wiring pattern 11 including the electrode. The protective coating 2 is located at the highest part of the insulating substrate 100. Preferably, the thickness of the protective coating is smaller than the thickness of the metal wiring pattern 11 including the electrode. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wiring board. Examples of the wiring board include a BGA board.

  When connecting an electrode on a wiring board to the wiring board and a lead wire with solder, a solder resist is laminated on the surface of the wiring board for the purpose of preventing the solder from flowing out to an adjacent electrode. .

  However, in recent development of semiconductor packages, attempts have been made to increase the degree of integration by narrowing the wiring interval in order to achieve high-frequency driving, high functionality, and miniaturization.

  Therefore, it is necessary to increase the height of the solder electrode by the thickness of the solder resist when connecting the semiconductor chip and the wiring substrate, particularly the BGA substrate, due to the thickness of the solder resist.

  If an attempt is made to increase the solder electrode by the thickness of the solder resist, the diameter of the solder electrode also increases, causing problems such as reversing the narrowing of the wiring interval and making it impossible to connect the electrodes.

  In order to overcome this problem, a method of overcoming the height of the solder resist by a method of structurally increasing the bump itself has been considered. However, these methods have a drawback that the number of steps increases.

JP-A-6-151587 JP-A-8-196704

  In view of the above problems, the present invention has a protective film formed with a solder flow prevention function equivalent to that of a solder resist, the thickness of which is thinner than that of a conventional solder resist, and the electrode is the highest position on the substrate. By providing the wiring board which exists in a, the connection distance of a wiring board and an electrical component is shortened. Another object of the present invention is to provide a wiring board that prevents the protective film from obstructing bonding when an electrical component is mounted using the wiring board, and a means that does not increase the number of steps in the manufacturing method.

According to the first aspect of the present invention, in the wiring board provided with a metal wiring pattern having an electrode in the uppermost layer, an electrically insulating protective film covering the wiring pattern including the electrode is formed, and the highest of the insulating board The wiring board is characterized in that the protective film is located at a location.
In other words, the invention according to claim 1 of the present invention has an electrode in the wiring board to which the electric component is connected, and at least has an electric insulation on the metal layer existing in the uppermost layer including the electrode. A protective film is formed, and there is only one type of protective film formed on the metal layer, and there is no protective film regardless of other types of organic / inorganic, insulating or conductive. It is a wiring board.

  That is, the wiring board is characterized in that the outermost surface of the protective film formed on the metal layer is the outermost in the thickness direction more than the constituents of the wiring board.

According to a second aspect of the present invention, in the wiring board according to the first aspect, the thickness of the protective film is less than the thickness of the metal wiring pattern including the electrodes.
In other words, the invention according to claim 3 of the present invention is characterized in that the thickness of the protective film formed is thinner than the thickness of the metal layer constituting the electrode provided on the uppermost layer of the wiring board. It is a wiring board described in 2 or 3.

A third aspect of the present invention is the wiring board according to the first or second aspect, wherein the protective film is a rust preventive film.
In other words, the invention according to claim 3 of the present invention is characterized in that the protective film forms a protective film exhibiting a rust preventive effect on the metal of the electrode or the wiring layer. This is a wiring board.

According to a fourth aspect of the present invention, there is provided a step of forming a protective film having electrical insulation so as to cover a metal wiring pattern having an electrode on the uppermost layer of the wiring substrate, and a step of heating the wiring substrate at 150 ° C. or higher. And a step of mounting solder on the electrode.
In other words, the invention according to claim 4 of the present invention includes a step of forming a protective film having electrical insulation on at least the uppermost metal layer of the wiring board, and then heating the wiring board at 150 ° C. A method of manufacturing a wiring board including a step of performing an aging treatment and a step of joining solder to an electrode portion on the wiring board.

A fifth aspect of the present invention is the method for manufacturing a wiring board according to the fourth aspect, wherein the solder does not contain lead.
In other words, in the invention according to claim 5 of the present invention, in the method of manufacturing a wiring board, a solder that does not contain lead is used for solder used for joining with an electrode. It is a manufacturing method.

According to a sixth aspect of the present invention, there is provided a step of forming a protective film having electrical insulation so as to cover a metal wiring pattern having an electrode on the uppermost layer of the wiring substrate, a step of applying heat to the wiring substrate, A method for manufacturing a wiring board, comprising: a step of pressing a conductive material against an electrode; and a step of applying an ultrasonic wave to the pressed conductive material.
In other words, the invention according to claim 6 of the present invention includes a step of forming a protective coating having electrical insulation on at least the uppermost metal layer of the wiring board, and preheating by applying heat to the wiring board. And a step of pressing a conductive substance responsible for energization with an electrical component against the electrode of the wiring board, and applying an ultrasonic wave to the conductive substance to weld the electrode and the conductive substance. This is a method for manufacturing a printed wiring board.

A seventh aspect of the present invention is a semiconductor device in which a semiconductor element is mounted on the wiring board according to the first to third aspects or the wiring board manufactured by the method according to the fourth to sixth aspects. .
In other words, in the invention according to claim 7 of the present invention, there is provided an electrical component connected to the wiring board described in claims 1 to 3 or the wiring board manufactured by the manufacturing method described in claims 4 to 6. A wiring board characterized by being a semiconductor element.

  According to the present invention, since the insulating protective film formed on the electrode on the wiring board exists at the highest position on the wiring board, the wiring board and the electrical component can be removed by removing only the protective film on the electrode. The distance between can be reduced. Further, according to the present invention, since the connection is possible even if a protective film is formed on all the electrodes, a process such as exposure and development is unnecessary, and the process can be shortened.

It is sectional drawing explaining the structure of the wiring board which concerns on embodiment of this invention. It is sectional drawing which shows the wiring board which concerns on embodiment of this invention. It is sectional drawing which shows the wiring board which concerns on embodiment of this invention.

As shown in FIG. 1, a wiring board 100 according to an embodiment of the present invention has a metal layer 1 on the main surface on an insulating base material layer (insulating board or wiring board) 3, and the metal layer 1 is protected. A film 2 is formed. In FIG. 1, vias, facing wiring, and the like are omitted. The wiring pattern 11 having electrodes is part of the metal layer 1.
The protective film 2 is preferably formed on the metal layer 1 on the wiring substrate 100. FIG. 1 shows an example in which the protective film 2 is formed only on the metal layer 1, but the film may be formed not only on the metal layer 1 but also on the insulating base material layer 3. However, at least the metal layer 1 needs to have a protective film 2 formed thereon, and the protective film 2 formed on the metal layer 1 needs to be present at the highest position on the wiring substrate 100. As a result, the distance between the electrodes 11 of the wiring board 100 and the electrical component 4 depends only on the protective film 2, and the distance between the electrodes can be made narrower by providing a means for thinning the protective film 2. It is.

  The wiring substrate 100 is configured by laminating one or more insulating base material layers 3 and metal layers 1. The insulating base layer 3 is a single layer, the metal layer 1 is a single layer, and these layers are laminated together, and the protective film 2 is laminated on the uppermost metal layer 1.

  As shown in FIGS. 2A and 2B, the wiring substrate 100 is formed by forming the metal layers 1 on both surfaces of the insulating base material layer 3, and has a multilayer structure. 2 (a) and 2 (b), the metal layer 1 and the protective film 2 are formed on both surfaces of the insulating base material layer 3, but the present invention can be formed only on one surface of the insulating base material layer 3. However, the present invention is not limited to this. The insulating base material layer 3 and the metal layer 1 can be used as a plurality of layers, respectively, and the insulating base material layer 3 and the metal layer 1 can be applied to a build-up wiring board configured by alternately laminating them.

  The metal layer 1 may be a layer made of copper foil, a copper plating layer, a layer made of metal paste, or the like, but the present invention is not limited to these. Other than copper, a metal material that can be used for wiring such as aluminum and silver can be used. When a metal foil or a metal plating layer is used as the metal layer 1, the metal layer 1 can be formed by etching after forming the copper foil or copper plating layer on the insulating base layer 3. Moreover, when using a metal paste as the metal layer 1, this metal paste can be printed in a desired pattern. By simultaneously forming the wiring pattern of the metal layer 1, the metal layer 1 is formed.

The protective film 2 is not particularly limited as long as it is an electrically insulating substance, and the metal layer 1 is protected by forming a thin glass film or vinyl chloride material on the substrate in order to protect the circuit board itself from the outside. However, the present invention is not limited to these materials. Furthermore, the protective film 2 can use a rust preventive agent for the purpose of preventing the oxidation of the metal layer 1, and in particular, when the metal layer 1 is copper, a benzotriazole type formed only on copper. , Imidazole, boron and the like, but is not limited thereto.
That is, the protective film 2 can be formed by applying a thin glass film on the surface of the substrate so as not to oxidize the metal layer 1 or forming it by a rust preventive film chemical treatment. When mounting the electrical components, the protective coating 2 is removed using ultrasonic waves or heat, so that the electrodes of the wiring board are exposed and can be connected.

  Furthermore, by making the thickness of the protective coating 2 thinner than the thickness of the metal layer 1, even if there is a protective coating 2 attached in addition to the metal layer 1, the thickness is less than or equal to the metal layer 1. This thickness is important because it does not interfere with the joining with the component 4.

  The insulating base material layer 3 can use an organic insulating base material such as polyimide resin or glass / epoxy resin, or a ceramic insulating base material such as an aluminum oxide sintered body or an aluminum nitride based sintered body. However, the present invention is not limited to these.

  An embodiment of the present invention is shown by taking FIG. 3 as an example. In FIG. 3A, the electric component 4 with the solder electrode 41 is placed on the wiring pattern 11 on the wiring substrate 100 on which the protective film 2 is formed on the metal layer 1. At this time, when the metal layer 1 is copper, it is suitable to use a rust preventive agent that forms a protective film only on the copper surface. The reason is that these protective coatings are very thin or can be easily removed at the time of joining with the solder.

  When mounting the electrical component 4 on the wiring board 100, if solder is used for the connection, the protective coating 2 can be removed by applying heat that melts the solder, and the wiring board 100 and the electronic component 4 are connected. Can do.

  Further, when a chemical solution characterized in that the protective coating 2 is intended to prevent rust of the copper coating is used, the heat resistance temperature of the protective coating is set before connecting the wiring board 100 and the electrical component 4 with solder. By heating at 150 ° C. or higher, the protective film 2 is altered and the metal layer 1 is oxidized. Thereby, the wettability of a solder can be reduced and flow-out can be suppressed. However, the oxide film is removed by the flux in the portion requiring the solder, and there is no problem in the connectivity.

  Furthermore, when the solder used to join the wiring substrate 100 and the electric substrate 4 does not contain lead, the wettability of the solder is worse than that of the solder containing lead, so that the effect of suppressing the flow out is increased.

  FIG. 3B mainly shows the case of a semiconductor element in which the electrode of the electrical component 4 is joined to the wiring substrate 100 using a protruding electrode 42 (for example, a gold bump). The film used at this time can be used not only for the rust preventive agent but also for the film for protecting the entire substrate. In this case, it is difficult to form a very thin protective film because the method of forming the film is different from the anticorrosive film, but this problem can be solved by an application method such as spray coating or vapor deposition. Further, the method is not limited to this.

  When the protruding electrode 42 is used for joining the wiring board 100 and the electric component 4, the electric component 4 is first fixed at a predetermined position on the preheated wiring board 100, and the protruding electrode is fixed with a certain force. 42 is pressed against the electrode 11 and an ultrasonic wave is applied to the protruding electrode 42, so that the protruding electrode 42 vibrates and generates heat between the wiring substrate 100 and the electrode 11 together with the action of preheating. The protective coating 2 is altered by the generated heat, and the coating is shaved by vibration. At the same time, the protruding electrode 42 and the metal wiring 11 are melted by the heat, and the wiring substrate 100 and the electrical component 4 are connected. This connection method is the same as the principle of known ultrasonic welding.

  Examples of the electrical components used for the above-mentioned joining include resistors, capacitors, inductors, and the like, but are not limited thereto, and semiconductor elements such as diodes, transistors, and semiconductor chips can be joined.

In any of the above-described embodiments, unlike the existing solder resist, it is not necessary to make an opening in the electrode portion. Therefore, the process can be shortened by forming the protective film 2 without requiring exposure and development. It is also possible to use existing equipment.
Example 1

Using a copper-clad laminate in which copper foil is laminated on both sides as an insulating base layer 3 with polyimide resin, after each step of degreasing, pickling, washing and drying, on one side, made by Shikoku Kasei Co., Ltd. The preflux agent indicated by the trade name “Tuff Ace F2 (LX) PK” was immersed for 1 minute at room temperature, washed, and then heated at 100 ° C. for 1 minute to dry the wiring board.
At this time, no solder resist is formed on the substrate.

  Next, the wiring board on which the protective film 2 was formed was dried at 175 ° C. for 30 minutes to oxidize the anticorrosive film.

  Print the lead-free solder on the dried wiring board using the printing method so that it is equal to the area of the electrode, and mount the chip capacitor with the electrode part made of lead-free solder on it, so that the maximum temperature is 240 ° C. The chip capacitor was connected to the wiring board by overheating.

The appearance after bonding was that the flow out to the wiring pattern ahead of the electrode was 1 mm, and a smooth arcuate fillet was formed from the top of the chip capacitor electrode to the end of the wiring board electrode. Further, it was confirmed that the wiring board 100 and the chip capacitor were energized by a continuity test, and it was confirmed that the present invention was effective.
(Example 2)

Prepare the same substrate as in Example 1, apply a room temperature glass coating agent indicated by the brand name “Shiragusitaru A6200” manufactured by Bokuto Kasei Kogyo Co., Ltd. with air spray, and dry for 24 hours to form a glass thin film on the substrate surface. The thickness of this glass film was measured with a stylus meter, and it was confirmed that the thickness was less than the metal layer.
At this time, no solder resist is formed on the substrate.

  Next, a semiconductor element is mounted on the substrate, and the wiring board and the semiconductor element are connected by gold bumps. The bump diameter was 25 μm, the heating temperature was 220 ° C., the ultrasonic output per bump was 130 mW, the weight was 50 g, and the firing time was 5 mSec.

  After the connection, a continuity test between the wiring board and the semiconductor element was performed to confirm that the continuity was established, and it was confirmed that the present invention was effective.

1: Metal layer 11: Wiring pattern, electrode 2: Protective film 3: Insulating base material layer 4: Electrical component 41: Solder electrode 42: Metal electrode 100: Wiring board

Claims (7)

In a wiring board provided with a metal wiring pattern having electrodes on the top layer,
An electrically insulating protective film covering the wiring pattern including the electrode is formed,
The protective film is located at the highest portion of the insulating substrate,
A wiring board characterized by that.   The wiring board according to claim 1, wherein a thickness of the protective film is less than a thickness of the metal wiring pattern including the electrodes.   The wiring board according to claim 1, wherein the protective film is a rust-proof film. Forming a protective coating with electrical insulation so as to cover a metal wiring pattern having an electrode on the uppermost layer of the wiring board;
Heating the wiring board at 150 ° C. or higher;
A step of mounting solder on the electrode;
The manufacturing method of the wiring board characterized by including.   The method for manufacturing a wiring board according to claim 4, wherein the solder does not contain lead. Forming a protective coating with electrical insulation so as to cover a metal wiring pattern having an electrode on the uppermost layer of the wiring board;
Applying heat to the wiring board;
Pressing the conductive material against the electrode;
Applying ultrasonic waves to the pressed conductive material;
The manufacturing method of the wiring board characterized by including.   A semiconductor device, wherein a semiconductor element is mounted on the wiring board according to claim 1 or the wiring board manufactured by the method according to claims 4 to 6.

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