JPH11220048A - Synthetic resin package and lead-frame method there to - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deformation of a lead frame and to avoid the discharge at welded resin, by forming an irregularity part higher than the thickness of the lead frame at the part at least one of a package main body or the opposing surface of a fixed plate, inserting the lead terminal of the lead frame into a recessed part, and performing ultrasonic welding of a projected part. SOLUTION: Each lead terminal 21 of a lead frame 1 is inserted into a recessed part 22 among the irregulairty parts 22 and 23 formed on the upper end part of a package main body 2, that is to say, the surface opposing a synthetic-resin fixing plate 3. These irregularity parts 22 and 23 are formed so that each lead terminal 21 of the lead frame 1 is arranged at the specified position. Furthermore, the height of the projected part 23 is set larger than the thickness of one lead frame 1. In the application of the ultrasonic wave, a horn 4 is lowered at the constant speed, and the wave is oscillated before the horn 4 comes into contact with fixing plate 3. Under the oscillated state, the horn 4 comes into contact with the fixing plate 3, the ultrasonic wave is transmitted to the projected part 23 of the package main body 2 and the projected part 23 of the package main body 2 is melted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for fixing a lead frame to a synthetic resin by an ultrasonic welding device, and a package manufactured by the method.

[0002]

2. Description of the Related Art In general, a lead frame is installed in a package on which a semiconductor element or an electronic component is mounted so as to electrically connect the outside and the inside of the package. Since the material of the package body can be manufactured at low cost, a synthetic resin is generally used. As a method of fixing the lead frame to the synthetic resin package, the lead frame is sandwiched between synthetic resin blocks, and the resin in contact with the lead frame is melted using an ultrasonic welding machine, and the lead frame is fixed to the package body. There is a way.

FIG. 6 is a cross-sectional view for explaining a conventional method of fixing a lead frame to a synthetic resin. FIG. 6A is a cross-sectional view of a lead terminal before ultrasonic welding viewed from a lateral direction. FIG. 3B is a cross-sectional view of the lead terminal before ultrasonic welding as viewed from the axial direction, and FIG. 3C is a cross-sectional view of the lead terminal after ultrasonic welding as viewed from the lateral direction. 6, reference numeral 51 denotes a lead frame; 52, a package main body made of synthetic resin; 53, a fixing plate made of synthetic resin for fixing the REIT frame 51 to the package main body; and 54, an ultrasonic wave transmitted to the fixing plate 53. Horn of ultrasonic welding machine. FIG.
1A and 1B, a lead frame 51 is placed on a package body 52, and a fixing plate 53 is placed on the lead frame 51. Horn 5 of ultrasonic welding equipment
Numeral 4 can move up and down, and presses the fixing plate 53 against the package body 52 during ultrasonic welding. When ultrasonic waves are applied to the fixed plate 53 via the horn 54, the fixed plate 53 and the lead frame 51 or the lead frame 5
The temperature at the portion where the package 1 and the package body 52 are in contact increases, and the contacting portion is melted. Since the fixing plate 53 is pressurized by the horn 54, the package body 5
Then, the lead frame 51 is lowered to the second side, the lead frame 51 is embedded in the resin, and is welded to the package body 52. Thus, the lead frame 51 is fixed to the main body 52.

[0004]

However, in such a conventional method of fixing a lead frame to a synthetic resin package, as shown in FIG. 6 (c), a fixing method in which the lead frame is in contact with the lead frame 51 by ultrasonic waves. Although the portion of the plate 53 melts, the portion below the portion of the fixing plate 53 and in contact with the lead frame 51 on the package body 52 side also melts. However, since the portion of the package body 52 that is in contact with the portion of the lead frame 51 that is not in contact with the fixing plate 53 does not melt, the lead frame is fixed to the fixing plate 53.
Therefore, the lead frame tip 51 a that is pushed into the package main body 52, bends at this portion, and extends inside the package main body 52 rises from the upper surface of the package main body 52. This lead frame tip 51a
Wire bonding for electrical connection with a semiconductor element or an electronic component (not shown) mounted on the package is performed, and the lead frame tip 51 a rises from the package body 52 supporting the lead frame 51. If it does, wire bonding may not be possible, or even if possible, the fixing strength may be weak, and stability may be lacking.

In general, the thermal expansion of synthetic resin differs greatly from that of the lead frame, and the adhesive strength of the synthetic resin to the lead frame is weak, and it is difficult to fix the lead frame with high strength only by ultrasonic welding.

Further, as described above, a part of the fixing plate 53 is melted by the ultrasonic wave, and the melted resin is pushed out of the package body 52 or into the package body 52 by the fixing plate 53 itself. The resin extruded outside remains on the edge as it is. In this case, due to the presence of the discharge resin 55a, the external dimensions are changed or the appearance is impaired, and the value as a product is lost. On the other hand, the discharged resin 55b extruded into the main body spreads over the lead frame 51 and adversely affects wire bonding, and hinders mounting of a jig used for the package main body 52 in a process or a cap for covering the package main body 52. . In this case, it is conceivable to reduce the height of the convex portion to be welded to reduce the amount of melting. However, the fixing plate may not be welded to the package body, or the welding strength may not be obtained.

Therefore, the object of the present invention is to:
An object of the present invention is to provide a method for fixing a lead frame to a synthetic resin package in which a lead frame does not bend even when fixed by ultrasonic waves and a welding resin is not discharged to the outside or inside of a main body.

[0008]

In order to achieve the above object, a method for fixing a lead frame to a synthetic resin package according to the present invention comprises a lead frame made of metal between opposing surfaces of a synthetic resin package body and a synthetic resin fixing plate. Sandwich
In a method of fixing using an ultrasonic welding machine, at least one of the opposing surfaces of the package body or the fixing plate is formed with an uneven portion higher than the thickness of the lead frame,
The lead terminal of the lead frame is inserted into the provided concave portion, and the convex portion is ultrasonically welded.

Further, in the method for fixing a lead frame to a synthetic resin package according to the present invention, at least one of the opposing surfaces of the synthetic resin package body and the fixing plate has a thickness higher than the thickness of the lead frame, and the protrusion of the uneven portion is provided. A protrusion having a height lower than the height of the portion is provided, and when the convex portion of the concave-convex portion is melt-pressed by the ultrasonic welding machine, the approach to the synthetic resin package body and the fixing plate is limited to a predetermined range. It is characterized by having made it.

A synthetic resin package according to the present invention is a synthetic resin package comprising a lead frame made of metal sandwiched and fixed between opposing surfaces of a synthetic resin package body and a synthetic resin fixing plate. At least one of the surfaces has an uneven portion higher than the thickness of the lead frame, a lead terminal of the lead frame is inserted into the concave portion, and the convex portion is ultrasonically welded.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS.

FIG. 1 is a partially cutaway sectional view showing the structure of a synthetic resin package in which an optical mounting board to which the present invention is applied is housed. As shown in FIG. 1, the synthetic resin package includes a package body 2 to which a lead frame 1 is fixed.
The lead frame 1 is fixed to an end face of the package body 2 by a synthetic resin fixing plate 3. The package body 2 is a U-shaped frame having one open side, and houses the optical mounting substrate 5 at the upper end inside the frame. The optical mounting substrate 5 is, for example, S
An optical IC 7, an optical element 8, an optical fiber array 9, and the like are mounted on an i semiconductor substrate 6. The optical fiber array 9 is fixed to the Si semiconductor substrate 6 by an optical fiber array fixing plate 10, and an optical fiber array tape 11 for leading the optical output of the optical fiber array 9 out of the package body 2.
Is joined to. The optical mounting substrate 5 further includes a lead frame 1 fixed to an end surface of the package body 2 around the optical mounting substrate 5.
Bonding 1 to a plurality of lead terminals constituting
2 electrically connected. On the lower surface of the optical mounting substrate 5 inside the package body 2, a heat sink 13 made of a metal block such as copper is housed. The lower end of the heat sink 13 is exposed from the lower end of the package body 2. The upper part of the package body 2 is covered with a resin cap 14.

FIG. 2 is a sectional view of an essential part of the synthetic resin package for explaining a method of fixing a lead frame to the synthetic resin package according to the present invention. In FIG. 1, (a) is a cross-sectional view of a lead terminal before ultrasonic welding, viewed from a lateral direction.
(B) is a sectional view seen from the axial direction of the lead terminal before ultrasonic welding, and (c) is a sectional view seen from the axial direction of the lead terminal after ultrasonic welding. In these figures, 1 is a lead frame, 2 is a synthetic resin package body, 3 is a synthetic resin fixing plate, and 4 is a horn for transmitting ultrasonic waves of an ultrasonic welding machine to a welding sample. As shown in FIG.
Each of the lead terminals 21 is inserted into the concave portion 22 of the concave and convex portions 22 and 23 formed on the upper end surface of the package body 2, that is, the surface facing the synthetic resin fixing plate 3.
These concave and convex portions 22 and 23 are formed so that each lead terminal 21 of the lead frame 1 is arranged at a predetermined position, and the width of the concave portion 22 is slightly larger than the width of the lead terminal 21. These uneven portions 22 and 23 fix the positions of many lead terminals 21 with high accuracy. In addition, the height of the protrusion 23 is larger than the thickness of the lead frame 1, and before welding, the package body 2 of the fixing plate 3
Are not in direct contact with the lead frame 1 but in contact with the projections 23 of the package body 2. As an example, each of these dimensions is such that the pitch of the lead terminals 21 is 0.65.
mm, the width of the lead terminal 21 is 0.3 mm, the thickness of the lead terminal is 0.15 mm, the width of the protrusion 23 of the package body 2 is 0.3 mm, the height of the protrusion 23 is 0.3 mm, and the length of the protrusion 23 2 (see FIG. 2A) 23 is 0.7 mm.

The application of the ultrasonic wave causes the horn 4 to descend at a constant speed and oscillate before the horn 4 comes into contact with the fixed plate 3.
In the oscillated state, the horn 4 comes into contact with the fixed plate 3, and the ultrasonic wave is transmitted to the convex portion of the package body 2. At this time, the convex portion 23 of the package body 2 melts. The fixing plate 3 is lowered together with the horn 4, but the position of the fixing plate 3 is 0.03 m from the position before welding.
When reaching the position where m is lowered, the ultrasonic wave is stopped. The horn 4 and the fixed plate 3 are both lowered by the application of the ultrasonic wave, and are lowered until the melted resin is hardened even after the ultrasonic wave is stopped. In this case, 0.1 mm from the welding start position of the fixed plate 3
, That is, the lower part of the fixing plate 3 stops at a position 0.05 mm above the lead terminal 21, and the welding is completed in the state shown in FIG. In this case, since the stop position of the fixed plate 3 greatly changes depending on the position where the ultrasonic wave is stopped, it is necessary to accurately set the position where the ultrasonic wave is stopped.

In the method for fixing a lead frame to a synthetic resin package according to the present invention, the lead terminals 21 are not in contact with the fixing plate 3 during ultrasonic welding. Not
Since the ultrasonic wave is not directly transmitted, the package body 2 in contact with the lower surface of the lead terminal 21 does not melt. As a result, the tip of the lead terminal 21 inside the package body 2 does not bend and does not float from the end face of the package body 2.

The fixed plate 3 is placed above the lead terminals 21 at a distance of 0.1 mm.
Since it stops at the position of O5 mm, as shown in FIG. 2C, the melted resin of the convex portion 23 of the package body 2 is buried in the concave portion 22 on the lead terminal 21 and the lead terminal 2
1 serves to fix the inside of the recess 22, and therefore does not flow out or inside the package body 2.

A part of the lead terminal 21 which is ultrasonically welded has a space which is not covered with the resin, but an adhesive is injected into the space from the inside of the package body 2 and hardened, thereby forming a lead frame. The fixing strength to the package body can be further increased.

FIG. 3 is a sectional view of a main part of a synthetic resin package for explaining a second embodiment of the present invention. In the above-described first embodiment, it is necessary to accurately set the position where the oscillation of the ultrasonic wave is stopped. However, in this embodiment, the fixed plate 3 can be automatically stopped at the fixed position.

In FIG. 3, (a) is a cross-sectional view of the lead terminal before ultrasonic welding as viewed from the lateral direction, and (b) is a cross-sectional view of the lead terminal after ultrasonic welding as viewed from the lateral direction. 2 are given the same reference numerals. As shown in FIG. 3A, the fixing plate 3 disposed above the lead terminal 21
Is extended from a portion of the package body 2 where the concave and convex portions 22 and 23 are formed to an inner portion of the package body 2, and furthermore, a projection 31 protruding toward the package body 2 is formed in this extended portion. I have. That is, the lower surface of the projecting portion 31 is
3 protrudes further below the lower surface of the fixed plate 3 where the portion 3 is formed. As an example, the dimensions of the projection 31 are such that the projection height with respect to the lower surface of the fixed plate 3 is 0.05 mm,
The length is O. 7 mm.

When ultrasonic waves are applied from above the fixing plate 3 through the horn 4, the projections 23 of the package body 2 are welded to the fixing plate 3. At this time, the stop position of the ultrasonic oscillation may be between 0.03 mm and 0.1 mm from the fixed plate start position.

In the method for fixing a lead frame to a synthetic resin package according to this embodiment, both the horn 4 and the fixed plate 3 are lowered with the application of ultrasonic waves, and are lowered even after the ultrasonic oscillation is stopped. The formed protrusion 31
The horn 4 and the fixing plate 3 are stopped from descending here because the horn contacts the lead terminal 21. Further, even if the ultrasonic wave is applied after the protrusion 31 of the fixing plate 3 comes into contact with the lead terminal 31, the contact area between the fixing plate 3 and the lead terminal 21 is newly increased. The load decreases.
For this reason, the temperature between the protrusion 31 of the fixing plate 3 and the lead terminal 21 is unlikely to rise, and the fixing plate 3 hardly drops further. Therefore, as shown in FIG. 3B, the position of the fixing plate 3 at the welded portion can be stably fixed at a position 0.05 mm above the lead terminal.

FIG. 4 is a sectional view of a main part of a synthetic resin package for explaining a third embodiment of the present invention. That is, FIG. 3 is a cross-sectional view of the synthetic resin package viewed from the axial direction of the lead terminal before ultrasonic welding, and the same parts as those in FIGS. 2 and 3 are denoted by the same reference numerals.

In this embodiment, the descent stop projections 41 having a height higher than the thickness of the lead terminal 21 and lower than the height of the projection 23 are provided on both sides of the portion of the package body 2 where the projections and depressions 22 and 23 are formed. 41 are provided. As an example, the height of the projections 41 is 0.20 mm.

In the method for fixing a lead frame to a synthetic resin package in this embodiment, if the stop of the application of ultrasonic waves is set to a position where the fixing plate 3 is lowered by a distance between 0.03 mm and 0.1 mm, the fixing plate 3 contacts the projections 41, 41 of the package body 2 so that the fixing plate 3
Stops at this position. As described above, the lead can be fixed to the synthetic resin package without strictly controlling the ultrasonic stopping position.

FIG. 5 is a cross-sectional view of a main part of a synthetic resin package for explaining a fourth embodiment of the present invention, which is a cross-sectional view as seen from the axial direction of a lead terminal before ultrasonic welding. 2, the same parts as those in FIGS. 2, 3 and 4 are denoted by the same reference numerals.

In the embodiment shown in FIG.
1 and 41 are formed on both sides of the portion of the package body 2 where the uneven portions 22 and 23 are formed. In this embodiment, as shown in FIG.
The same effect can be obtained by forming the descent-stop projection 51 on the upper surface. That is, the convex portion 23 of the package body 2 is further formed on the upper end of the descending stop projection 51, and the fixing plate 3 descends by application of the ultrasonic wave, and comes into contact with the upper end of the descending stop projection 51 and stops. The present invention is not limited to the above embodiment. For example, in the above embodiment, the uneven portion 2
Although the reference numerals 2 and 23 are provided on the package body 2, these irregularities may be provided on the fixing plate 3, or may be provided on both the package body 2 and the fixing plate 3.

[0027]

According to the present invention described above, it is possible to fix the lead terminal to the package body without bending the lead terminal or lifting the tip of the lead terminal inside the package body from the package body. At this time, the lead frame can be fixed to the resin package with good reproducibility without the molten resin of the package body being discharged to the inside and outside of the package body.

[Brief description of the drawings]

FIG. 1 is a partially cutaway sectional view showing a configuration of a synthetic resin package to which the present invention is applied.

FIG. 2 is a cross-sectional view of a main part of a synthetic resin package for explaining a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of a main part of a synthetic resin package for explaining a second embodiment of the present invention.

FIG. 4 is a cross-sectional view of a main part of a synthetic resin package for explaining a third embodiment of the present invention.

FIG. 5 is a sectional view of a main part of a synthetic resin package for explaining a fourth embodiment of the present invention.

FIG. 6 is a partially cutaway sectional view of a synthetic resin package for explaining a conventional fixing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lead frame 2 Package body 3 Fixing plate 4 Ultrasonic horn 21 Lead terminal 22 Concave part 23 Convex part 31 Projection part

Claims (3)

[Claims] 1. A method of clamping a lead frame made of metal between opposing surfaces of a synthetic resin package body and a synthetic resin fixing plate using an ultrasonic welding machine, wherein the opposing surface of the package body or the fixing plate is fixed. A synthetic resin package, characterized in that at least one of the concave and convex portions is formed higher than the thickness of the lead frame, the lead terminals of the lead frame are inserted into the concave portions, and the convex portions are ultrasonically welded. How to fix the lead frame to 2. A projection having a height lower than a height of a convex portion of the concave and convex portion is provided on at least one of opposing surfaces of the synthetic resin package body and the fixing plate, and the ultrasonic welder is used to form the convex and concave portions. 2. A method for fixing a lead frame to a synthetic resin according to claim 1, wherein, when the convex portion is melt-pressed, the approach between the synthetic resin package body and the fixing plate is limited to a predetermined range. 3. A synthetic resin package in which a lead frame made of metal is sandwiched and fixed between opposing surfaces of a synthetic resin package main body and a synthetic resin fixing plate, at least one of the opposing surfaces of the package main body or the fixing plate. A synthetic resin package, wherein an irregular portion is formed higher than the thickness of the lead frame, a lead terminal of the lead frame is inserted into the concave portion, and the convex portion is ultrasonically welded.