JP2002353394A - Wiring board with pin and electronic device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board with pins and an electronic device capable of excellently connecting lead pins through a socket and soldering to the wiring conductor of an outside electric circuit board without any displacement and unnecessary adhesion of a solder on the lead pins. SOLUTION: In the wiring board with the pins providing a solder bump 8 connected to the wiring conductor 2 on the upper face of an organic material- based insulation substrate 1 having the wiring conductor 2 and bonding the lead pins 3 connected to the wiring conductor 2 on the lower face of an insulation board 1 through the solder 9, the solder bump 8 consisting of alloy of lead of 67-82 wt.%, tin of 5-20 wt.%, antimony of 5-15 wt.% and bismuth of 8-20 wt.%, and the solder 9 consists of lead of 70-85 wt.%, tin of 5-20 wt.% and antimony of 5-15 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board with pins used for mounting electronic components such as semiconductor elements, and an electronic device having electronic components such as semiconductor elements mounted on the wiring board with pins. Things.

[0002]

2. Description of the Related Art Recently, as a wiring board with pins used for mounting electronic parts such as semiconductor elements, for example, an insulating plate made of a glass-epoxy plate or a plurality of insulating layers made of an epoxy resin are laminated. A plurality of wiring conductors made of copper foil are provided from the upper surface to the lower surface of the insulating substrate, and an electrode of an electronic component is connected via solder bumps to a portion of the wiring conductors led to the upper surface of the insulating base. A plurality of pinning pads are formed at parts where the component connection pads are led out to the lower surface of the insulating base, and a solder bump made of a lead-tin alloy is joined to these electronic component connection pads, and an iron-based alloy or the like is attached to the pinning pads. A wiring board with pins made of an organic material, which is obtained by joining substantially cylindrical lead pins made of a copper-based alloy via solder made of a lead-tin alloy, has been adopted. It has come. Such an organic material-based wiring board with pins is advantageous in that it is lighter in weight and has a smaller electric resistance of a wiring conductor than a wiring board with pins made of a ceramic material. In such an organic material-based wiring board with pins, the electronic component is mounted on the upper surface of the insulating substrate so that the electrode and the solder bump are in contact with each other, and the solder bump is heated and melted to form the electrode of the electronic component. And a solder bump, and thereafter, the electronic component is sealed with a lid made of metal or ceramic or a sealing member made of a potting resin, etc., thereby forming an electronic device as a product. The lead pins on the bottom surface of the board are connected to the wiring conductors of the external electric circuit board via sockets, solder, etc., so that they are mounted on the external electric circuit board and the mounted electronic components are electrically connected to the external electric circuit. Becomes

[0003]

However, in this conventional wiring board with pins and an electronic device using the same, the solder used for bonding the solder bumps or the lead pins to which the electrodes of the electronic parts are bonded is usually used. Are made of lead-tin eutectic solder, and solder made of lead-tin eutectic alloy has good wettability with lead pins made of iron-based alloy or copper alloy. Is joined via a lead-tin eutectic alloy solder, a part of the lead-tin eutectic solder wets and spreads to the lower end of the lead pin. A large amount of solder may adhere, and if such a large amount of solder adheres to the lower end of the lead pin, place the lead pin on the wiring conductor of the external electric circuit board using a socket or solder. It has been a problem that it becomes difficult to satisfactorily connect. Further, when the solder for joining the electrodes of the electronic component and the solder for joining the lead pins are both made of a lead-tin eutectic alloy, when joining the electrodes of the electronic component and the solder bump, the solder bump is melted. The solder that joins the lead pin to the pinning pad due to heat also melts and softens at the same time, causing a shift in the lead pin. In this case, the lead pin cannot be connected well to the wiring conductor of the external electric circuit board. Had the problem that

The present invention has been devised in view of the conventional problems, and has as its object to prevent solder from adhering to a lower end portion of a lead pin and to join an electrode of an electronic component to a solder bump. And the like, and an electronic device using the same can be connected to a wiring conductor of an external electric circuit board through a socket or solder without causing a shift in the lead pin. To provide.

[0005]

According to the present invention, there is provided a wiring board with pins according to the present invention, wherein solder bumps connected to wiring conductors are provided on an upper surface of an organic material-based insulating substrate having wiring conductors, and wiring conductors are provided on a lower surface of the insulating substrate. A wiring board with pins formed by joining lead pins connected to a solder via solder, wherein the solder bumps are composed of 67 to 82% by weight of lead, 5 to 20% by weight of tin and 5 to 15% by weight.
% Of antimony and 8 to 20% by weight of bismuth, and the solder for joining the lead pins consists of 70 to 85% by weight of lead, 5 to 20% by weight of tin and 5 to 15% by weight of antimony. It is characterized by the following.

In the electronic device of the present invention, a solder bump connected to a wiring conductor is provided on an upper surface of an organic material-based insulating substrate having a wiring conductor, and a lead pin connected to the wiring conductor is provided on a lower surface of the insulating substrate. An electronic device in which an electronic component is mounted on a wiring board with pins formed by bonding via solder and an electrode of the electronic component is electrically connected to a solder bump. Lead and 5-20
5% by weight of tin, 5-15% by weight of antimony and 8-20% by weight
And the solder for joining the lead pins is composed of 70 to 85% by weight of lead, 5 to 20% by weight of tin, and 5 to 15% by weight of antimony.

According to the wiring board with pins and the electronic device using the same of the present invention, the solder for joining the lead pins is
Since it is composed of an alloy of 70 to 85% by weight of lead, 5 to 20% by weight of tin and 5 to 15% by weight of antimony, such a composition moderately suppresses wettability with the lead pin, and as a result, When the lead pin is joined to the insulating substrate, the solder is effectively prevented from spreading to the lower end of the lead pin. Also, the solder bumps to which the electrodes of the electronic components are joined are 67 to 82
Of lead, 5 to 20% by weight of tin, 5 to 15% by weight of antimony and 8 to 20% by weight of bismuth. The melting point is lower than that of the solder composed of 20% by weight of tin and 5 to 15% by weight of antimony. Therefore, when joining the electrodes of the electronic component and the solder bumps, the solder for joining the lead pins is not softened and melted. The electrodes of the electronic component and the solder bumps can be joined.

[0008]

Next, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an example of an embodiment in which the present invention is applied to a wiring board with pins for mounting a semiconductor element and an electronic device having the semiconductor element mounted thereon, where 1 is an insulating substrate, 2 is a wiring conductor, 3
Is a lead pin. The insulating substrate 1, the wiring conductor 2, and the lead pins 3 constitute a wiring board with pins of the present invention,
The electronic device of the present invention is formed by mounting the semiconductor element 4 as an electronic component on this.

The insulating substrate 1 is made of a glass fabric in which glass fibers are woven vertically and horizontally, and is impregnated with a thermosetting resin such as an epoxy resin or a bismaleimide triazine resin. An organic material-based multilayer board formed by laminating a plurality of insulating layers 1b each made of a thermosetting resin such as a bismaleimide triazine resin, and a plurality of layers made of a copper foil, a copper plating film, or the like from the upper surface to the lower surface. The wiring conductor 2 is formed.

The core 1a constituting the insulating substrate 1 has a thickness.
It has a plurality of through-holes 5 of about 0.3 to 1.5 mm and a diameter of about 0.1 to 1.0 mm from the upper surface to the lower surface.
A part of the wiring conductor 2 is attached to the upper and lower surfaces and the inner wall of each through-hole 5, and the wiring conductors 2 on the upper and lower surfaces are electrically connected through the through-hole 5.

Such a core body 1a is manufactured by thermally curing a sheet in which a glass fabric is impregnated with an uncured thermosetting resin, and then performing drilling from the upper surface to the lower surface. The wiring conductors 2 on the upper and lower surfaces of the core 1a
Has a thickness of 3 to 50 μm on the entire upper and lower surfaces of the sheet for the core 1a.
A predetermined pattern is formed by attaching a copper foil of a degree and etching the copper foil after curing the sheet. The wiring conductor 2 on the inner wall of the through-hole 5 has a thickness of 3 to 50 μm after the through-hole 5 is formed in the core 1a and the inner wall of the through-hole 5 is formed by electroless plating and electrolytic plating.
It is formed by depositing a copper plating film of about m.

Further, the core 1a is filled with a resin column 6 made of a thermosetting resin such as an epoxy resin or a bismaleimide triazine resin in the inside of the through hole 5. The resin pillar 6 is for enabling the insulating layer 1b to be formed directly above and directly below the through hole 5 by closing the through hole 5.
An uncured paste-like thermosetting resin is filled in the through-holes 5 by screen printing, and after thermosetting, the upper and lower surfaces are polished to be substantially flat. The insulating layer 1 is formed on the upper and lower surfaces of the core body 1a including the resin column 6.
b is laminated.

An insulating layer 1b laminated on the upper and lower surfaces of the core 1a
Has a plurality of through holes 7 each having a thickness of about 20 to 60 μm and a diameter of about 30 to 100 μm from the upper surface to the lower surface of each layer. These insulating layers 1b are for providing an insulating interval for wiring the wiring conductors 2 at high density. By electrically connecting the upper layer wiring conductor 2 and the lower layer wiring conductor 2 through the through-hole 7, high-density wiring can be formed three-dimensionally. Such an insulating layer 1b is formed by attaching a film of an uncured thermosetting resin having a thickness of about 20 to 60 μm to the upper and lower surfaces of the core 1a, thermally curing the same, and forming the through holes 7 by laser processing. The insulating layer 1b is formed by successively stacking the next insulating layers 1b in a similar manner. In addition, each insulating layer 1b
The wiring conductor 2 attached on the surface and in the through hole 7 is formed by forming a copper plating film having a thickness of about 5 to 50 μm on the surface of each insulating layer 1b and in the through hole 7 every time the insulating layer 1b is formed. It is formed by applying a predetermined pattern by a pattern forming method such as a semi-additive method or a subtractive method.

The wiring conductor 2 formed from the upper surface to the lower surface of the insulating substrate 1 functions as a conductive path for connecting each electrode of the semiconductor element 4 to an external electric circuit board, and is provided on the upper surface of the insulating substrate 1. Part of the part is connected to the electronic component connection pad 2a connected to each electrode of the semiconductor element 4 via the solder bump 8, and part of the part exposed on the lower surface of the insulating substrate 1 is connected to the lead pin 3 as an external connection terminal. To form a pinning pad 2b. The solder bumps 8 are joined to the electronic component connection pads 2a, and the lead pins 3 are joined to the pinning pads 2b via the solder 9. As shown in the enlarged plan view of the main part of FIG. 2, the electronic component connection pad 2a and the pinning pad 2b are formed by forming the outer peripheral portion of the substantially circular pattern connected to the wiring conductor 2 on the outermost layer called solder resist. By covering the insulating layer 1b with a width of about 15 to 150 μm and defining the outer periphery thereof, the diameter φ is about 70 to 200 μm for the electronic component connection pad 2a, and substantially for the pinning pad 2b. It is formed to be about 0.5 to 2.5 mm.
The solder resist 1b effectively prevents an electrical short circuit between the electronic component connection pads 2a or the pinning pads 2b due to the solder 8 or 9, and also prevents the electronic component connection pads 2a and the pinning pads 2b.
Has a high bonding strength to the insulating substrate 1.

The solder bumps 8 bonded to the electronic component connection pads 2a are composed of 67-82% by weight of lead, 5-20% by weight of tin and 5% by weight of tin.
-15% by weight of an alloy of antimony and 8-20% by weight of bismuth, which functions as a connecting member for electrically connecting each electrode of the semiconductor element 4 to the wiring conductor 2 and insulates the semiconductor element 4 It functions as a fixing member for fixing on the substrate 1. Then, the semiconductor element 4 is mounted on the insulating substrate 1 such that each electrode and each solder bump 8 are in contact with each other, and these are heated to a temperature equal to or higher than the melting temperature of the solder bump 8 to melt the solder bump 8. Thereby, each electrode of the semiconductor element 4 and the solder bump 8 are joined, whereby each electrode of the semiconductor element 4 and the wiring conductor 2 are electrically connected via the solder bump 8 and the semiconductor element 4 is insulated. It is fixed on the substrate 1 via solder bumps 8.

The lead pins 3 joined to the pinning pads 2b are, as shown in an enlarged sectional view of a main part in FIG. 3, for example, an iron-based alloy such as an iron-nickel-cobalt alloy or an iron-nickel alloy, or a copper alloy. It is made of a copper alloy such as an iron-zinc-phosphorus alloy and has a diameter A of about 0.25 to 0.5 mm and a length of 1 to 3.5 mm.
The diameter B is 0.45 to 1.25 at the upper end of the substantially cylindrical shaft portion 3a of about
It is formed by forming a substantially disk-shaped large-diameter portion 3b called a nail head having a thickness T of about 0.05 to 0.3 mm. And
The large diameter portion 3b is joined to the pinning pad 2b with a solder 9 made of an alloy of 70 to 85% by weight of lead, 5 to 20% by weight of tin, and 5 to 15% by weight of antimony.
In this wiring board, the electrodes of the semiconductor element 4 are joined to the electronic component connection pads 2a via the solder bumps 8 to mount the semiconductor element 4 and the semiconductor element 4 is mounted on the wiring board. An electronic device is obtained by sealing the element 4 with a lid or a potting resin (not shown). The electronic device of the present invention is obtained by connecting the lead pins 3 in this electronic device to the wiring conductors of the external electric circuit board via a socket or solder. Is mounted on the external electric circuit board.

In the present invention, the solder bumps 8 to be joined to the electrodes of the semiconductor element 4 are composed of 67 to 82% by weight of lead and 5%.
The solder 9 for joining the lead pins 3 is made of an alloy of about 20% by weight of tin, 5% to 15% by weight of antimony, and 8% to 20% by weight of bismuth. It is important that it consist of an alloy of 5% by weight of tin and 5 to 15% by weight of antimony.

The solder bumps 8 to which the electrodes of the semiconductor element 4 are bonded are composed of 67 to 82% by weight of lead, 5 to 20% by weight of tin and 5 to 15% by weight.
% Of antimony and 8 to 20% by weight of bismuth. The lead pin 3 is joined with 70 to 85% by weight of lead, 5 to 20% by weight of tin and 5 to 15% by weight of antimony. The melting point of the solder 9 is lower by about 10 to 20 ° C. Therefore, when joining each electrode of the semiconductor element 4 and the solder bump 8, the solder bump 8
By melting the solder bumps 8 by heating at a temperature not lower than the melting temperature of the solder 9 and not higher than the melting temperature of the solder 9, each electrode of the semiconductor element 4 and the solder bumps 8 are joined without causing a shift in the lead pins 3. be able to.

If the content of lead contained in the solder bumps 8 is less than 67% by weight, the melting point of the solder bumps 8 becomes too low. For example, the lead pins 3 may be used as wiring conductors of an external electric circuit board. When a temperature of about 230 ° C. is applied, for example, when bonding is performed via solder made of a lead-tin eutectic alloy, the solder bump 8 melts and shifts between the electrode of the semiconductor element 4 and the solder bump 8. If the content exceeds 82% by weight, the melting point of the solder used for an organic material-based wiring board becomes too high, so that the solder bump 8 may be formed when the solder bump 8 is formed. When joining the solder bumps 4 with the solder bumps 8, there is a high risk that the heat for melting the solder bumps 8 may adversely affect the insulating substrate 1. Therefore, the content of lead contained in the solder bump 8 is specified in the range of 670 to 82% by weight.

If the content of tin contained in the solder bumps 8 is less than 5% by weight, the melting point of the solder bumps 8 tends to be too high. The wettability of the electrode becomes too good,
There is a high danger that a large amount of unnecessary intermetallic compounds will be formed between the electrodes of the semiconductor element 4. Therefore, the content of tin contained in the solder bump 8 is 5 to 20% by weight.
Specified in the range.

Further, antimony contained in the solder bumps 8 increases the solid phase temperature of the solder bumps 8 and imparts appropriate wettability to the solder bumps 8. If the content is less than 5% by weight, the semiconductor The wettability of the solder bumps 8 to the electrodes of the element 4 tends to be too good, and if it exceeds 15% by weight, the melting point of the solder bumps 8 tends to be too high and the mechanical strength tends to decrease. is there. Therefore, the content of antimony contained in the solder bump 8 is specified in the range of 5 to 15% by weight.

Further, bismuth contained in the solder bump 8 has an effect of lowering the melting point of the solder bump 8, and if the content is less than 8% by weight, the melting point of the solder bump 8 tends to be high. If it exceeds 20% by weight, the mechanical strength of the solder bump 8 tends to decrease. Therefore, the content of bismuth contained in the solder bump 8 is specified in the range of 8 to 20% by weight.

The solder 9 joining the lead pins 3
Is made of an alloy of 70 to 85% by weight of lead, 5 to 20% by weight of tin and 5 to 15% by weight of antimony, so that the wettability with the lead pin 3 made of an iron-based alloy or a copper-based alloy is not so high. Not good. Therefore, when joining the lead pin 3 and the pinning pad 2b via the solder 9, the solder 9 is effectively prevented from spreading on the shaft portion 3a of the lead pin 3,
As a result, the solder 9 does not adhere to the shaft portion 3a of the lead pin 3, and the lead pin 3 can be satisfactorily connected to the wiring conductor of the external electric circuit board via the socket or the solder.
Further, since the melting point is as low as about 260 to 270 ° C., the lead pin 3 and the pinning pad 2 b can be joined without adversely affecting the organic material-based insulating substrate 1.

If the content of lead contained in the solder 9 is less than 70% by weight, the melting point of the solder 9 becomes too low. When electrically connecting to the electronic component connection pad 2a
When the heat of about 230 ° C. is applied, the risk that the solder 9 is melted at the same time and the lead pin 3 is displaced increases, and if the heat exceeds 85% by weight, the solder used for the wiring board of the organic material is The melting point becomes too high, and when joining the lead pin 3 to the pinning pad 2b via the solder 9, there is a high danger that the heat for melting the solder 9 may adversely affect the insulating substrate 1. Therefore, the solder 9
Is specified in the range of 70 to 85% by weight.

When the content of tin contained in the solder 9 is less than 5% by weight, the melting point of the solder 9 tends to be too high. When the lead pin 3 is joined to the pinning pad 2b via the solder 9, the danger of part of the solder 9 flowing out to the shaft 3a of the lead pin 3 increases. Therefore, the content of tin contained in the solder 9 is specified in the range of 5 to 20% by weight.

Further, the antimony contained in the solder 9 increases the solid phase temperature of the solder 9 and imparts an appropriate wettability to the solder 9, and if the content is less than 5% by weight,
There is a tendency that the wettability of the solder 9 to the lead pins 3 tends to be too good, and if it exceeds 15% by weight, the melting point of the solder 9 tends to be too high and the mechanical strength tends to decrease. Therefore, the content of antimony contained in the solder 9 is specified in the range of 5 to 15% by weight.

The lead pin 3 is connected to the pin pad 2b.
In order to join the lead pins 3 via the solder 9, a predetermined amount of a solder paste for the solder 9 is applied to the pinning pad 2 b by screen printing using a metal mask, for example, and the large diameter portion 3 b of the lead pin 3 is formed thereon. A method is adopted in which the end faces are brought into contact with each other, heated at a temperature of about 260 to 270 ° C. for 1 to 2 minutes to melt the solder, and then cooled to room temperature.

Thus, according to the wiring board with pins of the present invention and the electronic device using the same, the lead pins 3 are not displaced and the solder 9 is attached to the shaft 3a of the lead pins 3.
The present invention can provide a wiring board with pins capable of satisfactorily connecting lead pins 3 to wiring conductors of an external electric circuit board via a socket or solder, and an electronic device using the same.

The present invention is not limited to the above-described embodiment, and it goes without saying that various changes can be made without departing from the scope of the present invention.

[0030]

According to the wiring board with pins of the present invention and the electronic device using the same, the solder for joining the lead pins is composed of 70 to 85% by weight of lead, 5 to 20% by weight of tin, and 5 to 15% by weight. % Of the alloy with antimony, the wettability with the lead pin is appropriately suppressed by such a composition, and as a result, when the lead pin is joined to the insulating substrate, the solder spreads at the lower end of the lead pin. Effectively prevented. Also, the solder bumps to which the electrodes of the electronic components are joined are:
70-85 wt% lead joining the lead pins, consisting of an alloy of 67-82 wt% lead, 5-20 wt% tin, 5-15 wt% antimony and 8-20 wt% bismuth And 5
The melting point is lower than that of a solder composed of -20% by weight of tin and 5-15% by weight of antimony. Therefore, when joining an electrode of an electronic component and a solder bump, no deviation occurs in a lead pin. As a result, it is possible to provide a wiring board with pins capable of satisfactorily connecting lead pins to a wiring conductor of an external electric circuit board via a socket or solder, and an electronic device using the same.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an embodiment of a wiring board with pins and an electronic device according to the present invention.

FIG. 2 is an enlarged plan view of a main part of an embodiment of a wiring board with pins and an electronic device according to the present invention.

FIG. 3 is an enlarged sectional view of a main part of an embodiment of a wiring board with pins and an electronic device according to the present invention.

[Description of Signs] 1... Insulating base 2... Wiring conductor 3... Lead pin 4... Semiconductor element as electronic component 8. .... Solder for joining lead pins 3

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/34 505 H05K 3/34 512C 512 3/46 Q // H05K 3/46 B23K 101: 40 B23K 101 : 40 H01L 23/12 PF term (reference) 5E319 AA03 AB05 AC01 AC02 AC15 AC16 AC17 AC20 BB04 BB05 CC33 CD04 CD26 GG03 GG09 GG15 5E336 AA04 BB03 BB11 CC32 CC44 DD39 EE03 GG06 GG09 5E346 AA06 AA12 BB15 GG25 HH11 HH31 5F067 AA16 AB07 BB20

Claims (2)

[Claims] An organic material-based insulating substrate having a wiring conductor is provided with a solder bump connected to the wiring conductor on an upper surface, and a lead pin connected to the wiring conductor is formed on a lower surface of the insulating substrate via solder. A wiring board with pins formed by bonding, wherein the solder bumps are an alloy of 67 to 82% by weight of lead, 5 to 20% by weight of tin, 5 to 15% by weight of antimony, and 8 to 20% by weight of bismuth. And the solder for joining the lead pins is 70 to 85% by weight of lead and 5 to 5% by weight.
A wiring board with pins, comprising 20% by weight of tin and 5 to 15% by weight of antimony. 2. An organic material-based insulating substrate having a wiring conductor is provided with a solder bump connected to the wiring conductor on an upper surface thereof, and a lead pin connected to the wiring conductor is formed on a lower surface of the insulating substrate via solder. An electronic device in which an electronic component is mounted on a bonded wiring board with pins by bonding an electrode thereof and the solder bump, wherein the solder bump has 67 to 82% by weight of lead and 5 to 20% by weight. % Of tin, 5 to 15% by weight of antimony and 8 to 20% by weight of bismuth, and the solder joining the lead pins is 70 to 85% by weight of lead, 5 to 20% by weight of tin and 5% by weight. ~
An electronic device comprising 15% by weight of antimony.