CN1983583A - Active device base and lead frame using same - Google Patents

Abstract

The invention discloses an active device base and a lead frame using the same, wherein the active device base comprises: a plate material; the predetermined bonding area of the active device is arranged on the surface of the plate; and at least one through hole distributed in the plate outside the preset adhesion area.

Description

Active device base and lead frame using same

technical field

The invention relates to an active device base and its application, in particular to an active device base capable of improving the reliability of a package and a lead frame using the base.

Background technique

Please refer to FIG. 1 , which is a cross-sectional view showing a known package using a lead frame with an active device base 10 and external contacts 20 as a substrate. The chip 30 is adhered on the active device base 10 and electrically connected to the external contact 20 by the bonding wire 32 . The packaging material 40 is used to isolate the chip 30 and the bonding wire 32 from the outside.

Taking the package shown in Figure 1 as an example, the lead frame is generally used as the package of the package substrate. When passing the reliability test specified by JEDEC (Joint Electron Device Engineering Council; which is the global semiconductor engineering standardization organization), due to the Due to the difference in thermal expansion coefficient between the source device base 10 and the packaging material 40 , the thermal stress borne by the packaging body may cause the two to separate from each other and cause delamination, so that the required reliability cannot be achieved.

In addition, based on concerns about environmental pollution, more and more countries or economies require electronic products to use lead-free soldering processes. However, the soldering temperature of the lead-free soldering process is generally higher than that of the solder using the tin-lead eutectic alloy by more than 40°C, and the requirements for the reliability of the package will be more stringent. Therefore, it is an important issue to develop a package with better reliability, especially a package with a lead frame as the package substrate.

Contents of the invention

In view of this, the main purpose of the present invention is to provide an active device base and a lead frame using the base. After the packaging is completed, the bonding force between the packaging material and the active device base can be strengthened to improve the use of the base. Electronic device reliability performance of the inventive active device submount and lead frame.

In order to achieve the above object of the present invention, the present invention provides an active device base, comprising: a plate; a predetermined adhesion area corresponding to the active device, located on the surface of the plate; and at least one through hole, distributed in the predetermined In the above boards outside the sticking area.

The present invention also provides a lead frame, comprising: a board; a predetermined adhesion area corresponding to an active device, located on the surface of the board; at least one through hole, distributed in the board other than the predetermined adhesion area; Points are provided around the plate at intervals; and edge portions are provided with the external contact point between the plate and connected to the plate and the external contact point respectively.

The feature of the present invention is to predetermine the adhesion area of the active device on the base of the active device, and design at least one through hole in the area other than the predetermined adhesion area of the active device. Therefore, after the encapsulation material is formed to cover the active device base, the encapsulation material can go deep into the active device base through the above-mentioned through holes, so as to "pin" the active device base, thereby improving the adhesion between the two force, thereby improving the reliability performance of the electronic device using the active device base and the lead frame of the present invention.

In order to make the above and other objects, features, and advantages of the present invention more comprehensible, the following preferred embodiments are specifically enumerated below together with the accompanying drawings, and are described in detail as follows.

Description of drawings

FIG. 1 is a cross-sectional view showing a known package.

Figure 2 is a top view showing the active device base and lead frame of the preferred embodiment of the present invention.

FIG. 3 is a sectional view along the section line AA of FIG. 2 .

Figure 4 is a cross-sectional view showing the function of the active device mount and lead frame of the preferred embodiment.

Symbol Description

10～active device base 20～external contact points

30～active device 32～welding wire

40～Encapsulation material 100～Active device base

101～diagonal line 102～diagonal line

104～plate 105～welding wire area

110～predetermined adhesion area 120～through hole

130～external contact point 140～edge

142～support device 150～packaging material

AA～hatching

Detailed ways

Please refer to FIGS. 2 and 3 , wherein FIG. 2 is a top view, and FIG. 3 is a cross-sectional view along the section line AA of FIG. 2 , showing the active device base and the lead frame of the preferred embodiment of the present invention.

As shown in FIG. 2, the active device base 100 of the present invention includes a plate 104, preferably a conductive material, which can provide the grounding of the active device (not shown) predetermined to be adhered thereon; and when applied to a lead frame, Sheet 104 is typically metal. On one surface of the board 104 , there is a predetermined adhesion area 110 for active devices;

The lead frame of the present invention includes the above-mentioned active device base of the present invention, a plurality of external contacts 130 , and an edge portion 140 . Wherein a plurality of external contact points 130 and the board 100 are disposed around it in a spaced manner. The external contact point 130 is located between the edge portion 140 and the board 100 , and is connected to the edge portion 140 . In addition, the edge portion 140 is connected to the plate 100 through the supporting device 142 .

The through hole 120 is usually formed by using a punching machine, and a punch with an appropriate size and shape is made in advance to form the through hole 120 by punching. In this embodiment, the shape of the through hole 120 is basically a circle, and those skilled in the art can also make punches of other shapes according to their needs, so as to form, for example, rectangles, polygons, stars, or other shapes. The through hole 120.

In addition, the wire bonding area 105 can be selectively formed outside the predetermined adhesive area 110 as required. In this way, after the active device is adhered on the predetermined adhesive area 110 , the above active device can be electrically connected to the bonding wire area 105 by a known wire bonding process, so as to provide its grounding. The known wire bonding process usually uses gold wires to connect the above-mentioned active devices and the active device base 100, so the bonding wire region 105 is usually plated with an adhesive layer (not shown) that has good adhesion to the plate 104 and gold. drawn). For example, when the board 100 is copper, the above-mentioned adhesion layer can be a nickel/gold layer, a nickel/palladium/gold layer, or other suitable materials. At this time, the through-holes 120 are distributed outside the wire bonding area 105 (different sides from the predetermined adhesion area 110 ).

The effect of the through hole 120 is shown in FIG. 4 , which is continued from FIG. 3 . In the lead frame of the present invention, the encapsulation material 150 is formed, and the encapsulation material 150 will enter and fill the through hole 120. The encapsulation material 150 "pins" the active device base 100, thereby improving the adhesion between the encapsulation material 150 and the active device base 100, which can avoid delamination caused by thermal stress separating the two, thereby The reliability performance of the electronic device using the active device base and the lead frame of the present invention is improved.

After the encapsulation material 150 is formed and the encapsulation is completed, the completed encapsulation body is usually mounted using a known surface mount technique, with the active device base 100 and external contacts 130 (not shown in FIG. 4 ) exposed in FIG. 4 , The adhesive used for electrical connection to the circuit board of a predetermined electronic product is usually a tin-based alloy solder. The encapsulation material 150 is usually filled with epoxy resin and silicon dioxide. In the above-mentioned surface mount process, the solder material cannot wet the encapsulation material 150 and connect with it. Therefore, the formation of the through hole 120 also relatively reduces the available adhesive area when the active device base 100 is connected with the above-mentioned circuit board. Therefore, the opening area of the through hole 120 on the surface of the board 104 should not be too large, so as not to substantially affect the adhesion strength between the active device base 100 and the above-mentioned circuit board. In this embodiment, when the opening area of the through hole 120 is no more than 5% of the area of the board 104 , it will not actually affect the adhesion strength between the active device base 100 and the circuit board.

In addition, in order to further improve product reliability, it is preferable to form more than one through hole 120 . At this time, it is considered that in general, the thermal stress caused by factors such as thermal process of the package, reliability test, or temperature cycle does not have a specific directionality when acting between the package material 150 and the board 104 . For the consideration of overall reliability, the distribution of the plurality of through holes 120 is preferably substantially symmetrically distributed with the geometric center of the plate 104 as a reference point, as shown in FIG. 2 . In this embodiment, the number of through holes 120 is four. In addition, generally speaking, starting from the geometric center of the plate 104, the closer to its edge or corner, the greater the thermal stress will be. Therefore, the closer the distribution of the through holes 120 is to the edge or corner of the plate 104, the greater the impact on lifting. The effect of reliability is greater.

In this embodiment, the shape of the board 104 is basically a rectangle, and other shapes such as polygonal boards 104 can also be used as required. In FIG. 2 , the four corners near the diagonals 101 and 102 of the plate 104 are farthest from the geometric center of the plate 104 , and will bear the highest stress value when thermal stress acts. Therefore, it is better to place the four through holes 120 at the four corners of the plate 104 respectively, and it is better to allow the diagonal lines 101 and 102 to pass through the through holes 120, so that the effect of improving the reliability will be more significant.

Likewise, considering the adhesive strength between the active device base 100 and the circuit board of a given electronic product, the total opening area of the plurality of through holes 120 on the surface of the board 104 is preferably no more than 5% of the area of the board 104 . Therefore, relatively speaking, the number of through holes 120 should not be too large, because under the above conditions, the more the number of through holes 120 is, the smaller the opening area of each through hole 120 will be. When the opening area of the through hole 120 is too small to allow the silicon dioxide filling of the packaging material 150 to enter, as shown in FIG. Droplets of liquids such as gas or water that may accumulate in the through hole 120 will rapidly increase in size when the packaged body undergoes thermal processes such as surface adhesion processes, reliability tests, and temperature cycles. The so-called "popcorn effect" (popcorn effect) caused by the expansion of the ratio will be counterproductive, and will have a negative impact on product reliability performance. Therefore, the number of the through holes 120 must be determined according to the process requirements and the characteristics of the packaging material 150 used. As in this embodiment, when the board 104 is rectangular, the number of the through holes 120 is preferably four.

To sum up, according to the present invention, at least one through hole 120 is designed in the area of the board 104 other than the predetermined adhesion area 110 of the active device. Therefore, after forming the encapsulation material 150 to cover the active device submount 100, the encapsulation material 150 can penetrate into the active device submount 100 through the through hole 120, so as to be able to "pin" the active device submount 100 and lift both. The adhesive force between them can improve the reliability performance of the electronic device using the active device base and the lead frame of the present invention, so as to achieve the above object of the present invention.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore The scope of protection of the present invention should be defined by the claims.

Claims (16)

1. An active device base, comprising: plate; a predetermined adhesion area corresponding to the active device, the predetermined adhesion area is located on the surface of the board; and At least one through hole is distributed in the board outside the predetermined adhesion area. 2. The active device submount according to claim 1, wherein the board further comprises a wire bonding area outside the predetermined adhesive area, and the through holes are distributed outside the wire bonding area. 3. The active device base according to claim 1, wherein the active device base comprises a plurality of the through holes, which are substantially symmetrically distributed therein with the geometric center of the board as a reference point. 4. The active device base as claimed in claim 1, wherein the board is rectangular, and the active device base comprises four through holes, and the geometric center of the board is used as a reference point, substantially symmetrically distributed on within it. 5. The active device submount according to claim 4, wherein a diagonal line of the board passes through the plurality of through holes. 6. The active device submount as claimed in claim 1, wherein the opening area of the through hole is no more than 5% of the area of the board. 7. The active device submount as claimed in claim 3, wherein the total opening area of the plurality of through holes is no more than 5% of the area of the board. 8. The active device submount as claimed in claim 4, wherein the total opening area of the plurality of through holes is not greater than 5% of the area of the board. 9. A lead frame comprising: plate; A predetermined adhesion area corresponding to the active device, the predetermined adhesion area is located on the surface of the board; at least one through hole distributed in the board outside the predetermined adhesion area; a plurality of external joints spaced from the sheet around its perimeter; and The plurality of external connection points are arranged between the edge portion and the plate, and are respectively connected to the plate material and the plurality of external connection points. 10. The lead frame according to claim 9, wherein the board further comprises a wire bonding area outside the predetermined adhesive area, and the through holes are distributed outside the wire bonding area. 11. The lead frame as claimed in claim 9, wherein the active device base comprises a plurality of the through holes, which are substantially symmetrically distributed therein with the geometric center of the board as a reference point. 12 . The lead frame of claim 9 , wherein the board is rectangular, and the active device base comprises four through holes, which are substantially symmetrically distributed in the board with the geometric center of the board as a reference point. 13 . 13. The lead frame of claim 12, wherein a diagonal line of the board passes through the plurality of through holes. 14. The lead frame as claimed in claim 9, wherein the opening area of the through hole is no more than 5% of the area of the plate. 15. The lead frame of claim 11, wherein a total opening area of the plurality of through holes is not greater than 5% of the area of the board. 16. The lead frame of claim 12, wherein a total opening area of the plurality of through holes is not greater than 5% of the area of the board.

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