JP2012084806A - Mounting semiconductor device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mounting semiconductor device in which confirmation of solder wetting is easy.SOLUTION: In a mounting semiconductor device, using a mounting substrate having a die pad attaching land and a lead attaching land, and a lead frame in which the die pad is positioned lower than the inner part of the lead, an extention extended continuous from the die pad to near an end of a bottom of a resin sealing body and a part formed on the die pad attaching land corresponding to the extention extended further outside are formed, and a semiconductor chip mounted to the lead frame is sealed by the resin sealing body, and a semiconductor package in which the die pad and the extention are exposed on the bottom of the resin sealing body is mounted on the mounting substrate by soldering, and a solder layer reaches the bottom end of the resin sealing body, forming a protrusion which enables a visual inspection.

Description

  Embodiments of the present invention relate to a mounted semiconductor device and a method for manufacturing the same.

  2. Description of the Related Art Resin-encapsulated semiconductor devices are known as encapsulated semiconductor devices that are rich in mass productivity and can reduce costs. In general, a resin-encapsulated semiconductor device uses a lead frame having a die pad (tab or island) for mounting a semiconductor chip, a suspension lead for supporting the die pad, and a lead for leading an electrode of the semiconductor chip to the outside.

  The semiconductor chip is die-bonded on the die pad of the lead frame, the bonding pad on the semiconductor chip is wire-bonded to the inner lead of the lead frame, the sealing resin is molded over the semiconductor chip, and the lead protruding from the resin sealing body is formed. The semiconductor package is made by bending and cutting tie bars, dams, frames, and the like. In order to facilitate wire bonding, a configuration in which the die pad of the lead frame is submerged from the inner lead and the upper surface of the semiconductor chip is aligned with the upper surface of the inner lead is also known.

  It is also desired to quickly dissipate heat generated in the semiconductor chip incorporated in the sealing portion (package) to the outside of the sealing portion. A configuration for efficiently radiating heat using a lead frame on which a semiconductor chip is mounted has been proposed.

  In JP-A-6-268142, the die pad is submerged from the lead, the top surface of the chip is made almost the same height as the lead, and is molded with a resin sealing body so as to enclose the chip, the die pad, and the inner part of the lead. In the configuration where the outer part is bent downward from the bottom of the die pad into a crank shape (so-called gull wing shape) and soldered to the mounting board, the support bar (hanging lead) of the die pad is widened and extended on the mounting board together with the lead to dissipate heat. A configuration for improving the performance is disclosed.

  A structure is known in which the back surface (lower surface) of a support plate (tab) to which a semiconductor chip is fixed is exposed to the back surface (bottom surface) of a sealing portion. The lead outer portion is bent to have the same height as the die pad, for example. The lead is soldered to the wiring of the mounting substrate, and the die pad exposed on the bottom surface of the semiconductor package is soldered to the thermal diffusion pad on the mounting substrate.

  Japanese Patent Application Laid-Open No. 2004-235217 discloses a tab portion on which a die pad chip is mounted in a structure in which a die pad exposed on the bottom surface of a resin sealing body and a lead extending in a gull wing shape from the side surface of the resin sealing body are soldered onto a mounting substrate. A tab-exposed semiconductor device that has a shape that protrudes into the sealing resin and further has a convex portion that cuts into the sealing resin in a saw-tooth shape to suppress thermal deformation and prevent peeling between the chip and the die pad. To do.

  Japanese Patent Application Laid-Open No. 2003-224239 temporarily folds the lead upward, then folds it outward above the wire, and molds it with a resin body so that the upper end surface of the lead and the bottom surface of the die pad are exposed on the surface and back surface of the resin sealing body. A configuration is described in which the tip of the lead is soldered to the mounting substrate by inverting. The die pad is exposed upward (on the opposite side to the mounting substrate), improving heat dissipation. A non-lead type semiconductor device is described in which the outer portion of the suspension lead of the die pad is bent to the same level as the lead to increase the mounting area. A recess is formed on the back surface (mounting surface) of the resin sealing body so that it can be accommodated even if dust is generated.

  In Japanese Patent No. 4351150 (WO2003 / 005475), a die pad (tab), a tab suspension lead, and a lower surface of a lead tip are located on the same plane, and a chip including a plurality of circuits is bonded to the upper surface of the tab. The ground electrodes of some circuits are wire-bonded to the leads together with the electrodes, etc., and the ground electrodes of the remaining circuits are wire-bonded to the tabs. A suspension lead and a non-lead type semiconductor device in which the mounting surface protrudes from the lower surface of the lead are described.

JP-A-6-268142 JP 2004-235217 A JP 2003-224239 A Japanese Patent No. 4351150

  Provided is a mounting semiconductor device in which solder wettability can be easily confirmed in a configuration in which a die pad exposed to the bottom surface of a resin sealing body together with the tip of a lead led out to the outside of the resin sealing body is soldered to a mounting substrate.

According to the example,
A mounting substrate having a die pad bonding land and a lead connection land on the surface;
A lead frame having a die pad sinking from a plane on which an inner portion of the lead exists, a semiconductor chip die-bonded on the die pad, a wire connecting the semiconductor chip and the inner portion of the lead, and a resin A semiconductor package including a sealing body, wherein the die pad is exposed on a bottom surface of the resin sealing body, and an outer portion of the lead is bent outside the resin sealing body to form a connection region substantially flush with the die pad. When,
A solder layer for connecting the lead connection region to the lead connection land, and bonding the die pad to the die pad connection land;
Including
The semiconductor package includes an extension that extends to the bottom of the bottom of the resin sealing body continuously to the die pad,
The die pad connection land has a portion corresponding to the die pad and a portion corresponding to the extension portion, and the portion corresponding to the extension portion reaches the outside of the bottom end portion of the resin sealing body, and the die pad connection The solder layer between the portion corresponding to the extension portion and the extension portion of the land for use reaches the bottom end portion of the resin sealing body and forms a protruding portion.
A mounted semiconductor device is provided.

  The solder wettability can be confirmed visually without using X-rays.

When, 1A and 1B are a cross-sectional view schematically showing a mounting semiconductor device according to the first embodiment and a back view of the semiconductor package, and FIGS. 1C to 1E are back views of the semiconductor package, a plan view of a mounting base, and a mounting substrate. It is a top view of the state which mounted the semiconductor package on it. 2A to 2C are a rear view of a semiconductor package, a plan view of a mounting substrate, and a plan view of a state in which the semiconductor package is mounted on a mounting substrate according to a second embodiment. 3A and 3B are rear views of a semiconductor package according to a modification. When, 4A to 4I are cross-sectional views showing main steps of a method for manufacturing a mounted semiconductor device according to the second embodiment. 5A and 5B are a plan view and a cross-sectional view schematically showing a lead frame that can be used in the second embodiment, and FIG. 5C is a plan view schematically showing a lead frame that can be used in the first embodiment. It is.

  In the mounting semiconductor device in which the die pad is exposed on the bottom surface of the resin sealing body, the leads are led out from the side surface of the resin sealing body, and the semiconductor package bent downward is fixed to the mounting base by soldering. Solder wettability with the corresponding land on the mounting board has a significant effect on heat dissipation. In a semiconductor device that requires high heat dissipation, it is necessary to ensure solder wettability. The die pad is located at the center of the plastic package, and the solder layer between the die pad and the corresponding land after mounting cannot be seen from the outside, so the solder wettability between the package and the mounting board is observed with X-rays. ing.

  However, some semiconductor devices cannot be irradiated with X-rays. When the mounting substrate is a double-sided mounting, the solder wettability cannot be confirmed by X-ray at the portion where the solder wet regions overlap. A solder wettability confirmation method other than X-rays is desired.

  The inventors of the present invention studied to visually confirm the solder wettability by extending the die pad exposed to the package and the corresponding land of the mounting substrate partially outward so that the solder protrudes to the package end.

  1A and 1B are a cross-sectional view of a mounting semiconductor device and a rear view of the semiconductor package showing an outline of the first embodiment. 1A is a cross-sectional view taken along line IA-IA in FIG. 1B.

  As shown in FIG. 1A, the die pad 11 exposed on the back surface of the semiconductor package 10 continues to the extension portion 12 extending to the vicinity of the end portion of the resin sealing body 7. The semiconductor chip 1 is fixed to the die pad 11 with a conductive adhesive 3 such as an Ag paste. The bonding wire 5 connects an electrode (bonding pad) on the semiconductor chip 1 to a lead, and connects a ground electrode on the chip to the die pad 11 as necessary.

  As shown in FIG. 1B, the resin encapsulant 7 exposes the die pad 11 and the extension 12 extending in four directions from the center of the upper, lower, left and right sides on the back surface, and molds the semiconductor chip to mold the semiconductor package. Form. In this configuration, the extension portion 12 is parallel to two sides of the rectangular semiconductor package (perpendicular to the other two sides). Generally, it arrange | positions in the direction in alignment with 2 sides of a semiconductor package. The lead 13 is led out from the center of the thickness of the resin sealing body 7 on the surface pulled up from the die pad 11. The mounting substrate 20 is a glass epoxy resin substrate having a multilayer wiring exemplified by the four-layer wiring in FIG. 1A, and the uppermost wiring layer corresponds to the die pad 11 and its extension part 12 together with the lead connection land, and the extension part. 12 has a package mounting land 22 that extends outward from 12 and reaches the outside of the end of the semiconductor package 10. A heat radiating via conductor 23 is formed below the land 22.

  The semiconductor package 10 is connected to the mounting substrate 20 by the solder layer 17 to form a mounting semiconductor device 30. The solder layer 17 bonded to the die pad 11 and its extension 12 of the semiconductor package 10 and the land 22 of the mounting substrate has an end surface protruding outside the semiconductor package 10 and exposed. The observer 35 can confirm the wettability of the solder by visually observing the edge of the semiconductor package 10.

  1C, 1D, and 1E are plan views schematically showing the relationship between the back surface of the semiconductor package 10, the surface of the mounting substrate 20, and the top surface of the mounting semiconductor device to which these are connected. FIG. 1C schematically shows FIG. 1B, and there is no substantial difference.

  As shown in FIG. 1D, a die pad and an extension bonding land 22 and a lead connection land 23 are arranged on the surface wiring layer of the mounting substrate 20. The lead connection land 23 is connected to the wiring on the back surface of the mounting substrate through multilayer wiring.

  As shown in FIG. 1E, the lead 13 is connected to the lead connection land 23 with a solder layer, and the die pad and the extension are connected to the corresponding land 22 with a solder layer. The solder layer melts to wet the die pad 11, the extension 12, and the land 22, and reaches the end of the semiconductor package 10. A part of the solder layer 17 reaching the bottom end of the resin sealing body protrudes outward. By visually observing the solder protrusion 32 at the end of the semiconductor package 10, the wettability of the solder can be confirmed.

  By extending the die pad and the corresponding land to the outside, the solder layer formed between them reaches the bottom end of the resin encapsulant and partially protrudes, so that the solder wettability can be confirmed visually, and the bonding area The increase in adhesion increases the adhesive strength, and based on the increased adhesion area, the thermal resistance decreases and the heat dissipation improves.

  In addition, although the extension part of the die pad has been arranged parallel to the outer side of the semiconductor package, the extension part of the die pad can take various forms.

  2A, 2B, and 2C show an example in which the extension portion 12 of the die pad 11 is formed along a direction connecting the top portions at the diagonal positions of the semiconductor package (referred to as a diagonal direction). Correspondingly, the shape of the die pad of the mounting base 20 and the land 22 corresponding to the extended portion has a region extending diagonally. When the semiconductor package 10 is connected to the mounting substrate 20, the solder layer 17 protrudes and the protruding portion 32 is formed on the diagonal edge of the semiconductor package 10 corresponding to the extension portion 12.

  By connecting the extension 12 to the outside of the die pad 11, the bonding area increases. An increase in the bonding area also results in an increase in adhesive strength and an improvement in heat dissipation.

  Although the pattern in which the extension portion extends in four directions from the die pad has been described, the number of directions in which the extension portion extends can be increased or decreased.

  FIG. 3A shows an arrangement in which extensions 12 are formed in the diagonal direction in addition to the vertical and horizontal directions from the die pad 11. By forming the extension in eight directions, the bonding area is increased, and the bonding strength and heat dissipation are further improved.

  FIG. 3B shows a pattern in which the extension is extended only in two directions. If the area of the extension portion is reduced, the improvement of the adhesive strength and heat dissipation is prevented accordingly, but the solder wettability can be confirmed visually as long as the solder layer reaches the bottom end portion of the resin sealing body and protrudes.

  Next, a method for manufacturing a mounted semiconductor device will be described by taking the configuration of the second embodiment shown in FIGS.

  As shown in FIG. 4A, the conductive adhesive 3 formed of Ag paste is applied on the die pad 11 of the lead frame 8. An extension 12 extends outward from the die pad 11 on the same plane as the die pad 11.

  5A and 5B show examples of the shape of the lead frame used in this example. The lead frame 8 has a shape corresponding to a plurality of semiconductor chips. Only the peripheral portion of one semiconductor chip mounting portion is shown. 5A is a plan view, and FIG. 5B is a cross-sectional view taken along line VB-VB in FIG. 5A. 4A to 4I are cross-sectional views along the diagonal direction of the semiconductor package as in FIG. 5B.

  In FIG. 5A, the die pad 11 is arranged at the center, and a predetermined number of leads 13 are arranged outside the four sides. Although the number of leads is shown as 5 × 4, the number of leads and the number of pins are arbitrary, and the actual number of pins is larger. The leads 13 are connected to each other by a tie bar 14 and supported by a frame. The die pad 11 is disposed on the same plane and includes an extension portion 12 extending in a diagonal direction. The outer end portion of the extension portion is pulled up by a suspension lead 15 and connected to the frame body. Since the die pad 11 is supported on the frame body by the extension portion 12 and the suspension lead 15, the extension portion 12 also functions as a suspension lead. As shown in FIG. 5B, the die pad 11 is disposed at a submerged height with respect to the surface on which the lead 13 exists. The suspension lead 15 connects this height difference. When a semiconductor chip is disposed on the die pad 11, the upper surface of the chip becomes almost the same height (level) as the upper surface of the leads 13. The extension portion 12 is disposed on substantially the same plane as the die pad 11. The die pad 11 is spaced apart from the inner ends of the plurality of leads 13 and is disposed further inside. The extension portion 12 is arranged so as to enter the outside (lead side) from the line connecting the inner end portions of the plurality of leads 13.

  As shown in FIG. 4B, the diced semiconductor chip 1 is placed on the conductive adhesive 3, heated to flow the conductive adhesive 3, cooled, and the semiconductor chip 1 is fixed on the die pad 11. To do.

  As shown in FIG. 4C, the electrodes (bonding pads) on the semiconductor chip 1 and the leads 13 are bonded with wires 5 such as gold wires. If necessary, the ground electrode of the semiconductor chip 1 is wire bonded to the die pad 11. If the die pad 11 is a common ground terminal, the number of ground leads may be reduced.

  As shown in FIG. 4D, a resin such as an epoxy resin containing a filler is molded so as to wrap the semiconductor chip 1 connected on the die pad 11 of the lead frame 8 and the wire 5 connecting the semiconductor chip and the lead. 7 is formed. The outer portion of the lead 13 extends outside the resin sealing body 7. The tie bar 14 and the like are removed by punching.

  As shown in FIG. 4E, after plating the surface of the lead 13 protruding to the outside of the resin sealing body 7, the lead 13 is bent. The bottom surface (connection region) of the bent lead 13, the die pad 11 exposed on the bottom surface of the package 10, and the extension portion 12 are arranged on substantially the same plane. Note that even if they are not physically strict planes, they are referred to as substantially the same plane when they can be regarded as the same plane in mounting. The lead connection area is substantially flush with the exposed surface of the die pad.

  As shown in FIG. 4F, a solder paste 17p is applied on the die pad-compatible land 22 on September 20, 2010 on the mounting substrate. The land 22 has a shape corresponding to the die pad 11 and the extension portion 12, and a portion facing the extension portion 12 is longer than the extension portion 12. In addition, although the mounting board | substrate which has 4 layer wiring is illustrated schematically, as shown to FIG. 1A, wiring is isolate | separated and connected according to a circuit.

  As shown in FIG. 4G, the semiconductor package 10 obtained in the step of FIG. 4E is disposed on the solder paste 17p.

  As shown in FIG. 4H, a heating process is performed on this configuration, the flux is evaporated from the solder paste 17p, and the solder is melted. Thereafter, the temperature is lowered to solidify the solder, and the semiconductor package 10 is fixed on the mounting substrate 20. The solder layer 17 connects the land 22, the die pad 11, and the extension 12, and the end reaches the outside of the semiconductor package 10.

  As shown in FIG. 4I, the end portion of the solder layer 17 reaches the end portion of the semiconductor package 10 and protrudes to the outside, so that the observer 35 can visually confirm the solder wettability.

  In the above process, the suspension lead was also used as an extension part of the die pad. Of course, the extension part of the suspension lead and the die pad can be created separately.

  FIG. 5C shows a shape in which the suspension leads 15 are formed in the diagonal direction of the die pad 11 and the extension portions 12 are arranged from the central portion of the four sides to the vicinity of the tie bar 14. It can be used in the embodiment shown in FIGS. Similar to the lead frame of FIG. 5A, the extension portion 12 is disposed in substantially the same plane as the die pad 11. The die pad 11 is spaced apart from the inner ends of the plurality of leads 13 and is disposed further inside. The extension portion 12 is arranged so as to enter the outside (lead side) from the line connecting the inner end portions of the plurality of leads 13.

  In the configuration of FIG. 5C, a suspension lead connected to the tie bar 14 may be provided at the tip of the extension portion 12. In this case, the suspension leads 15 provided in the diagonal direction of the semiconductor package can be replaced with leads.

  As mentioned above, although this invention was demonstrated along the Example, this invention is not limited to these. It will be apparent to those skilled in the art that various modifications, substitutions, improvements, combinations, and the like can be made.

1 Semiconductor chip,
3 conductive adhesive layer,
5 wires,
7 Resin encapsulant,
8 Lead frame,
10 Semiconductor package,
11 Die pad,
12 Extension,
13 leads,
14 Tie bar,
15 hanging leads,
17 Solder layer,
20 mounting base,
22 rand
30 Mounting semiconductor device,
32 Extruding part.

Claims (5)

A mounting substrate having a die pad bonding land and a lead connection land on the surface;
A lead frame having a die pad sinking from a plane on which an inner portion of the lead exists, a semiconductor chip die-bonded on the die pad, a wire connecting the semiconductor chip and the inner portion of the lead, and a resin A semiconductor package including a sealing body, wherein the die pad is exposed on a bottom surface of the resin sealing body, and an outer portion of the lead is bent outside the resin sealing body to form a connection region substantially flush with the die pad. When,
A solder layer for connecting the lead connection region to the lead connection land, and bonding the die pad to the die pad connection land;
Including
The semiconductor package includes an extension that extends to the bottom of the bottom of the resin sealing body continuously to the die pad,
The die pad connection land has a portion corresponding to the die pad and a portion corresponding to the extension portion, and the portion corresponding to the extension portion reaches the outside of the bottom end portion of the resin sealing body, and the die pad connection The solder layer between the portion corresponding to the extension portion and the extension portion of the land for use reaches the bottom end portion of the resin sealing body and forms a protruding portion.
Mounting semiconductor device.   The mounting semiconductor device according to claim 1, wherein the extension portion is disposed on substantially the same plane as the die pad.   The mounting semiconductor device according to claim 1, wherein the extension portion is disposed in a direction along two sides of the semiconductor package or in a direction along a diagonal direction.   The mounting semiconductor device according to claim 1, wherein the extension portion also functions as a suspension lead that supports the die pad. Using a lead frame having a structure in which the die pad is sunk from the plane where the inner portion of the lead exists, a semiconductor chip is die-bonded on the die pad,
A wire is connected between the semiconductor chip and the lead,
Forming a resin sealing body covering the semiconductor chip and the wire, exposing the die pad on the bottom surface of the resin sealing body;
Bending a lead projecting out of the resin sealing body, and forming a semiconductor package by arranging an adhesive region in substantially the same plane as the bottom surface of the die pad;
On the surface, a solder paste layer is formed on each land of the mounting substrate having a land for lead connection and a land for bonding a die pad,
Placing the semiconductor package on the solder paste layer;
The solder paste layer is heated, melted, cooled and solidified to form a solder layer, the lead is connected to the lead connection land, and the die pad is bonded to the die pad bonding land.
In a method for manufacturing a mounted semiconductor device,
The semiconductor package has an extension portion extending substantially in the same plane to the resin pad bottom end portion continuously to the die pad, exposing the extension portion on the resin seal bottom surface,
The die pad bonding land has a portion corresponding to the die pad and a portion corresponding to the extension portion, and the portion corresponding to the extension portion reaches the outside of the bottom end portion of the resin sealing body, and is heated and melted. After that, the solidified solder layer reaches the bottom end of the resin sealing body to form a protruding portion.
A method of manufacturing a mounted semiconductor device.

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