WO2019134268A1

WO2019134268A1 - Substrate, method for forming package structure by using substrate, and package structure

Info

Publication number: WO2019134268A1
Application number: PCT/CN2018/080876
Authority: WO
Inventors: 段银祥; 周萌; 徐虎; 田梓峰; 张世忠; 许颜正
Original assignee: 深圳市绎立锐光科技开发有限公司
Priority date: 2018-01-05
Filing date: 2018-03-28
Publication date: 2019-07-11
Also published as: CN110010557A; CN113922205B; CN113922205A; CN110010557B

Abstract

Provided is a substrate (1), comprising: a substrate body (11), a first recess structure (12), and a second recess structure (13). The substrate body has a bonding surface that bonds a bonded component (3) by means of a bonding material (2). The first recess structure is formed in the bonding surface, and comprises an opening having a size equal to the size of the bonded component so that the bonded component can be oriented in a plane direction of the bonding surface. The second recess structure is formed in the first recess structure and has a second depth such that the first recess structure has a first depth less than the second depth only at a plurality of support positions along the perimeter, wherein the bonded component can be supported in a vertical direction at the support positions.

Description

Substrate, method and package structure for forming package structure using substrate

Technical field

The present invention relates to a substrate, a substrate packaging method, and a package structure, and more particularly to a substrate capable of strictly controlling thickness uniformity of a bonding material and positioning of a bonded member in a device packaging process, a package structure forming method using the substrate, and a package structure.

Background technique

A light source that uses a blue laser diode (LD) to excite a wavelength conversion device has the advantages of high efficiency, high brightness, and the like. However, since the blue LD has a small spot size and a large power, and thus its optical power density is large, the heat dissipation performance of the wavelength conversion device is required to be high. A typical wavelength conversion device having, for example, a "thermally conductive substrate + diffuse reflection layer + luminescent layer" structure cannot meet its heat dissipation requirements. In contrast, the "thermally conductive substrate + diffuse reflection layer + luminescent layer" structure is more advantageous for heat dissipation.

At present, the "thermally conductive substrate + diffuse reflection layer + luminescent layer" structure mainly uses solder to weld metallized luminescent ceramic or glass to a copper substrate. Fig. 1 shows such a wavelength conversion device package structure. As shown in FIG. 1, the package structure includes a copper substrate 1, a solder paste 2, a wavelength conversion chip 3 composed of a wavelength converting material 32 and a metallization layer 31, and a lens group 4. In this configuration, the excitation light having the wavelength λ1 is incident to the wavelength conversion material 32 through the lens group 4, so that the wavelength conversion material 32 emits a laser light having a wavelength λ1 different from the wavelength λ1.

The solder paste 2 is a bonding layer for connecting the wavelength conversion chip 3 as a member to be bonded to the copper substrate 1. The thickness of the solder paste 2 becomes uneven due to the influence of the viscosity, wettability, and soldering process of the solder material. At the same time, the fluidity and uncontrollability of liquid tin during the reflow soldering process can cause the position of the wavelength conversion chip to drift and/or skew. The offset chip will affect the light collection efficiency of the lens group 4 and the assembly of the entire light source system.

In order to solve the misalignment of the joined member and the thickness uniformity of the bonding layer, the following technique has been proposed.

For example, the patent document CN104517931B proposes a substrate provided with an array of protruding fulcrums on the surface. The thickness uniformity of the solder layer between the liner and the substrate is controlled by an array of fulcrums on the substrate. Further, the array of fulcrums is located on the back side of the liner and/or around the four corners of the surface of the substrate. This design allows the fulcrum array to resist the flow of the solder layer while supporting, thereby minimizing the chance of voids and discontinuous solder joints in the solder layer. However, the use of this copper substrate does not solve the problem of lining offset. Moreover, in order to solve the problem of the lining offset, it is necessary to correct by the positioning fixture, which increases the complexity and cost of the process.

Patent document CN105814681A proposes a substrate having a groove structure. In the substrate, the opening of the recess is larger than the member to be joined, and the outer peripheral portion of the recess faced by the outer peripheral edge of the joined member is deeper than the central portion of the recess. The invention is mainly for solving the problem that the chip position shift in the high-power semiconductor soldering process affects the deterioration of the yield of the subsequent metal wire bonding. The substrate can improve the positional deviation of the chip in the planar direction, but the substrate cannot control the position of the chip in the vertical direction due to the uncontrollability of the solder in the vertical direction.

In summary, there are some problems in soldering wavelength conversion chips to common copper substrates by means of tin-based alloy eutectic soldering. Specifically, in the soldering process, due to the uncontrollability of the tin alloy in the liquid state, the thickness of the soldering layer may be inconsistent after soldering, causing the wavelength conversion chip to be skewed and misaligned, and the consistency of the sample after soldering is poor.

Summary of the invention

In view of the deficiencies of the prior art, the present invention aims to prevent the joint member from being misaligned and to control the uniformity of the thickness of the bonding material so that the bonded member after welding is kept parallel with the substrate and the lens, thereby ensuring maximum light collection efficiency. In addition, the present invention also aims to control the consistency of the thickness of the bonding material of different samples, thereby reducing the debugging work of different samples in the later stage.

According to a first aspect of the present invention, there is provided a substrate comprising: a substrate body having a bonding surface for bonding the bonded member with a bonding material; a first groove structure, the first concave a groove structure formed in the joint surface and having an opening size equal to a size of the joined member to enable positioning of the engaged member in a planar direction of the joint surface; and a second groove structure, a second groove structure for accommodating the bonding material, the second groove structure being formed in the first groove structure and having a second depth such that the first groove structure is only capable of being along the periphery A plurality of support positions supporting the joined member in the vertical direction have a first depth smaller than the second depth.

According to a second aspect of the present invention, there is provided a method of forming a package structure using the above-described substrate, the method comprising: providing the substrate; printing a bonding material to a bonding surface of the member to be joined; Attaching the joined component to the first groove structure of the substrate in a manner that the bonding surface of the component faces the substrate; placing a weight on the bonded component; The assembly including the substrate, the joined member, and the weight is placed in a vacuum eutectic furnace for welding to allow the bonding material to flow freely in the second groove structure of the substrate And after the welding is completed, the weight is removed.

According to a third aspect of the present invention, there is provided a package structure comprising: the substrate described above; a member to be joined; and a bonding material for bonding the member to be bonded to the substrate Said joint surface.

According to the present invention, since the opening size of the first groove structure completely corresponds to the size of the member to be joined, the first groove structure can accurately position the engaged member in the substrate in the planar direction.

Further, according to the present invention, since the depth of the first groove structure at the plurality of support positions along the periphery is smaller than the depth of the second groove structure, the first groove structure can support the joined member in the vertical direction.

Thus, according to the first to third aspects of the invention, it is possible to strictly control the thickness uniformity of the bonding material and the positioning of the joined member in the device packaging process.

The technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments will be briefly described below, and the drawings in the following description are only some embodiments of the present invention. Other embodiments and their drawings may be derived from the embodiments shown in the drawings without departing from the scope of the invention.

Fig. 1 shows a package structure of a prior art wavelength conversion device.

Fig. 2 shows a perspective view of a substrate according to a first example of the present invention.

Fig. 3 shows a plan view of a substrate according to a first example of the present invention.

Fig. 4 shows a cross-sectional view taken along line A-A of Fig. 3.

Fig. 5 shows a cross-sectional view taken along line B-B of Fig. 3.

Fig. 6 shows a plan view of a package structure according to a first example of the present invention.

Fig. 7 shows a cross-sectional view taken along line C-C of Fig. 6.

Fig. 8 shows a cross-sectional view taken along line D-D of Fig. 6.

FIG. 9 shows a perspective view of a substrate according to a modification example 1 of the first example.

FIG. 10 shows a perspective view of a substrate according to a modification example 2 of the first example.

Fig. 11 shows a perspective view of a substrate according to a modification example 2 of the first example.

Fig. 12 shows a perspective view of a substrate according to a modification example 3 of the first example.

Figure 13 shows a perspective view of a substrate in accordance with a second example of the present invention.

Detailed ways

The technical solutions of the various embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

Note that the drawings are schematic and are not drawn based on actual scales. The relative dimensions and proportions of the components illustrated in the figures are exaggerated or reduced in size, and any dimensions are merely exemplary and not limiting. The same structures, elements or components in the drawings are denoted by the same reference numerals.

First example of substrate

2 to 5 illustrate a substrate according to a first example of the present invention. Specifically, FIG. 2 shows a perspective view of a substrate of the present invention. Figure 3 shows a plan view of a substrate of the present invention. 4 and 5 respectively show cross-sectional views taken along line A-A and line B-B of Fig. 2.

6 to 8 illustrate a state of a package structure formed using a substrate according to a first example of the present invention. Specifically, FIG. 6 shows a plan view of the package structure. 7 and 8 show cross-sectional views taken along line C-C and line D-D of Fig. 6, respectively.

The substrate of the present invention can be used to package various high power electronic chips, such as wavelength conversion chips and the like. For purposes of illustration only, wavelength conversion chips are described herein as an example. At this time, solder paste is used as an example of the bonding material.

The substrate 1 of the present invention includes a substrate body 11, a first groove structure 12, and a second groove structure 13.

As shown in FIG. 2, for example, the square substrate 1 may be formed by punching or cutting a copper plate material, wherein the copper plate material may have a thickness of 2 mm to 10 mm, preferably 3 mm. The planar size of the copper substrate 1 may be 20 mm * 20 mm. As the material of the substrate 1, a pure copper or a copper alloy having a thermal conductivity of 300 w/m·k or more may be used, and a copper material having a thermal conductivity of 398 w/m·k is preferable. Generally, in order to prevent molecular diffusion and/or improve corrosion resistance and the like, the copper substrate is subjected to nickel plating treatment.

The first groove structure 12 and the second groove structure 13 are formed on the bonding surface of the substrate body 11 for bonding the wavelength conversion chip 3 by a process such as laser etching, chemical etching, or machining. In the present example, the wavelength conversion chip 3 may be an electronic chip such as a wavelength conversion chip.

The first groove structure 12 is for positioning the wavelength conversion chip 3 in the planar direction and supporting the wavelength conversion chip 3 in the vertical direction. In the field of electronic chips, the shape of the electronic chip as the wavelength conversion chip 3 is generally square in view of cost and process simplification, but various shapes such as a rectangle, a triangle, a hexagon, and a circle are not excluded. In order to achieve positioning and support of the wavelength conversion chip 3, the planar shape of the first groove structure 12 (i.e., the shape in Fig. 3) should correspond to the shape of the wavelength conversion chip. Specifically, the opening size of the first groove structure 12 must be equal to the size of the wavelength conversion chip.

For purposes of illustration only, in this example, as shown in FIG. 3, the planar shape of the first groove structure 12 is square. In this case, the wavelength conversion chip 3 should also have a square shape. In FIG. 3, the width (side length) of the first groove structure 12 is represented by W0, wherein W0 should satisfy W0 = the width (side length) of the wavelength conversion chip, whereby the first groove structure 12 can be in the planar direction Position the wavelength conversion chip. Here, for example, W0 = 5 mm.

The second groove structure 13 is a groove structure further formed in the first groove structure 12 and has a depth H2 (see FIG. 8). The second groove structure 13 is a space for allowing the solder paste 2 to freely flow during the reflow soldering process.

In the present example, as shown in FIGS. 2 and 8, the first groove structure 12 has a depth H1 smaller than the depth H2 only at the four corners along the circumference. That is, in the first groove structure 12, the formation position of the second groove structure 13 is a position other than the four corners. Thereby, the first groove structure 12 has four corner support positions which can be used to support the wavelength conversion chip 3 in the vertical direction along the periphery.

Further, in an optional but preferred feature, in order to allow free flow of excess bonding material during the reflow soldering process with the bonding material 3 exceeding a prescribed amount, the second groove structure 13 may further be from the first recess The four sides of the slot structure 12 extend outwardly into the exterior of the first groove structure 12 in four directions. In other words, the second groove structure 13 also extends outwardly from the periphery of the first groove structure 12 between the four corner support locations to the exterior of the first groove structure 12.

Thereby, by re-welding the second groove structure 13 to the outside of the first groove structure 12, as compared with the case where the second groove structure 13 does not extend to the outside of the first groove structure 12. The effect and effect of free flow of excess bonding material during the process.

However, it will be understood by those skilled in the art that although the second groove structure 13 is shown as having a portion extending outside the first groove structure 12 in all of the drawings of the present invention, the second The groove structure 13 does not necessarily have to extend outward. Under the premise that the production process can ensure an appropriate amount of bonding material, the second groove structure without outward extension is sufficient to allow free flow of the bonding material during the reflow soldering process. In this case, the second groove structure 13 is formed only in the first groove structure 12. At the four sides of the first groove structure 12, the second groove structure 13 is flush with the first groove structure 12. The same applies to the examples described later.

Nevertheless, in the present example, as shown in FIGS. 2 to 8, the case where the second groove structure 13 is extended to the outside of the first groove structure 12 is specifically explained as an example.

Thus, in the case where the second groove structure 13 extends to the outside of the first groove structure 12, the second groove structure 13 is formed by the portion formed in the first groove structure 12 and formed in the first groove structure 12 The outer part is composed and thus has a cross-shaped planar shape.

As shown in FIG. 3, the second groove structure 13 has a length W1 and a width W2. Since the second groove structure 13 is formed at a position other than the four corner support positions in the first groove structure 12, as shown in FIG. 5, the width W2 of the second groove structure 13 should be smaller than the first recess. The width W0 of the groove structure 12. Moreover, since the second groove structure 13 extends from the periphery of the first groove structure 12 between the four corner support positions to the outside of the first groove structure 12, as shown in FIG. The length W1 of the groove structure 13 should be greater than the width W0 of the first groove structure 12. Here, for example, the difference between W0 and W2 may be 1 mm to 2 mm, preferably 1 mm. For example, the difference between W1 and W0 may be from 3 mm to 15 mm, preferably 5 mm.

6 to 8 illustrate a state of a package structure formed using a substrate according to a first example of the present invention. A process of forming a package structure using the substrate according to the present invention and a package structure formed thereby will be described below with reference to FIGS. 6 to 8.

Before the wavelength conversion chip 3 is soldered to the substrate 1, the solder paste 2 is printed on the bonding surface (for example, the metalized surface) of the wavelength conversion chip 3, for example, by a stencil printing method. Then, the wavelength conversion chip 3 is attached to the first groove structure 12 in such a manner that the bonding surface of the wavelength conversion chip 3 on which the solder paste is printed faces the substrate 1. Thereafter, a weight is placed on the wavelength conversion chip 3. Then, the assembly including the substrate, the wavelength conversion chip, and the weight block obtained at this time was placed in a vacuum reflow furnace, and welding was performed in accordance with the set temperature and pressure curves. At this time, the bonding material is free to flow in the second groove structure 13 of the substrate. Finally, after the welding is completed, the weights are removed. At this time, the package structure shown in FIG. 6 is obtained.

Of course, it should be understood that the formation of the package structure and the package structure may also utilize substrates of other examples described below.

As shown in FIG. 6, the depth H1 of the first groove structure 12 is equal to or smaller than the thickness H0 of the chip 3. Here, for example, the thickness of the chip 3 is H0 = 300 μm. For example, the difference between H0 and H1 may be 0 to 100 μm, preferably 50 μm.

For example, the depth H2 of the second groove structure 13 is greater than the thickness H0 of the chip 3. As can be seen from Fig. 9, the solder paste 2 has a thickness of H2-H1 and a value of 100 to 300 μm, preferably 150 μm.

According to the present example, since the opening size of the first groove structure 12 completely corresponds to the size of the chip 3, the first groove structure can accurately position the chip 3 in the substrate 1 in the planar direction. Even during the reflow soldering process, the chip 3 does not drift in the planar direction due to the fluidity and uncontrollability of the solder paste 2.

In addition, according to the present example, since the depth H1 of the four corner support positions of the first groove structure 12 is smaller than the depth H2 of the second groove structure 13, the first groove structure 12 can support the chip 3 in the vertical direction, Thus, the chip 3 does not undergo any skew during the reflow soldering process.

Further, according to the present example, since the second groove structure 13 is formed in the first groove structure 12 and has a depth greater than the depth of the first groove structure 12, the solder paste 2 can be freely performed during the reflow soldering process Flowing, thereby improving the uniformity of the thickness of the solder paste 2 between the chip 3 and the substrate 1. In addition, alternatively, since the second groove structure 13 may further have a portion extending to the outside of the first groove structure 12, even if the solder paste 2 exceeds a prescribed amount during the reflow soldering process, the second recess can be The groove structure 13 flows freely, thereby improving the uniformity of the thickness of the solder paste 2 between the chip 3 and the substrate 1.

In a first example, the second groove structure extends outwardly from a perimeter of the first groove structure between the plurality of support locations. However, the second groove structure may also extend outwardly from a portion of the perimeter of the first groove structure between the plurality of support locations. Hereinafter, this case will be explained by enumerating the modification examples 1 to 3.

FIG. 9 shows a perspective view of a substrate according to Modification Example 1.

In the first example, the second groove structure 13 extends outward from the four sides of the first groove structure 12 to the outside of the first groove structure 12. However, as shown in FIG. 9, in the modification example 1, the second groove structure 13 extends outward from the three sides of the first groove structure 12 to the outside of the first groove structure 12, but not from the first concave The remaining one of the slots 12 (in this example, the upper side) extends outwardly.

As can be seen from Figure 9, at the upper side, the first groove structure 12 and the second groove structure 13 are flush.

The same effects and effects as those of the first example can also be obtained with the substrate according to the present modification example.

10 and 11 show perspective views of a substrate according to a modification example 2.

In the first example, the second groove structure 13 extends outward from the four sides of the first groove structure 12 to the outside of the first groove structure 12. However, as shown in FIGS. 10 and 11, in the modification example 2, the second groove structure 13 extends outward from the two opposite or adjacent sides of the first groove structure 12 to the outside of the first groove structure 12. But without the remaining two opposite sides of the first groove structure 12 (in this example, the upper and lower sides of Figure 10) or adjacent sides (in this example, the lower side of Figure 11 And the right side) extends outward.

As can be seen from Figure 10, at the upper and lower sides, the first groove structure 12 and the second groove structure 13 are flush. As can be seen from Figure 11, at the lower and right sides, the first groove structure 12 and the second groove structure 13 are flush.

FIG. 12 shows a perspective view of a substrate according to Modification Example 1.

In the first example, the second groove structure 13 extends outward from the four sides of the first groove structure 12 to the outside of the first groove structure 12. However, as shown in FIG. 12, in the modification example 3, the second groove structure 13 extends outward from one side of the first groove structure 12 to the outside of the first groove structure 12, but without the first groove The remaining three sides of structure 12 (in this example, the upper side, the lower side, and the left side) extend outward.

As can be seen from Figure 12, at the upper, lower and left sides, the first groove structure 12 and the second groove structure 13 are flush.

In the above first example and its modification examples 1 to 3, a plurality of support positions are provided at the four corners of the periphery of the first groove structure. However, as long as these support positions can support the chip in the vertical direction, the number of these support positions can be more or less, and the set position can be not limited to the corner position. For example, it is also possible to provide a support position at a central portion of any side of the first groove structure and/or to omit a support position at one or two respective corners of the side.

In addition, in the above first example and its modification examples 1 to 3, the first groove structure has a square planar shape. However, since the chip may also have other shapes than squares, the first groove structure may also be other shapes than squares, such as rectangles, triangles, hexagons, circles, and the like. In this case, generally, a plurality of support positions may be appropriately disposed along the circumference of the first groove structure to be capable of supporting the chip in the vertical direction. In addition, similar to the first example and its modified examples 1 to 3, the second groove structure may also extend outward from at least a portion of the periphery of the first groove structure between the plurality of support positions.

Second example of substrate

Figure 13 shows a substrate in accordance with a second example of the present invention. The second example is an improvement to the first example.

As shown in FIG. 13, a high thermal conductivity heat conduction stage 5 for conducting heat from the chip 3 is further provided in the second groove structure 13 for improving the thermal performance of the package structure. In addition to this, other configurations of the substrate according to the second example may adopt configurations of the first example and its modifications.

For example, the thermal pad 5 may be a portion of the material that is intentionally retained when the second groove structure 13 is formed in the substrate 1. At this time, the material of the heat transfer stage 5 is the same as that of the substrate. Since the thermal conductivity of copper is 7 to 8 times higher than that of tin, the thermal conductivity can be improved by forming the high thermal conductivity thermal conduction stage 5.

The upper surface of the heat conducting stage 5 is at most flush with the bottom of the first groove structure 12, i.e., does not exceed the bottom of the groove structure 12 in height. The heat transfer stage 5 is formed below the heat generating position of the wavelength conversion chip, that is, below the area for receiving and converting the excitation light. Further, the shape of the upper surface of the heat transfer stage 5 corresponds to the spot shape of the excitation light, and may be any shape such as a square, a rectangle, or a circle. Further, the area of the upper surface of the heat transfer stage 5 is slightly larger than the area of the area of the wavelength conversion chip that receives the excitation light.

During the reflow soldering process, a very thin solder paste is formed between the thermal pad 5 and the wavelength conversion chip 3 under vacuum and capillary forces. At this time, the strength of the wavelength conversion device is not lowered, but the thickness of the solder paste at the spot is reduced, thereby greatly reducing the thermal resistance of the solder paste.

In addition to the above effects, the substrate according to the second example can also obtain the same actions and effects as the first example and its modified example.

Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited thereto, and those skilled in the art will understand that the present invention may be practiced without departing from the spirit or scope of the appended claims. Make various changes, combinations, sub-combinations, and variants.

Claims

A substrate comprising:

a substrate body having a bonding surface for bonding the bonded member with a bonding material;

a first groove structure formed in the joint surface and having an opening size equal to a size of the joined member to enable positioning of the engaged in a planar direction of the joint surface Parts; and

a second groove structure for accommodating the bonding material, the second groove structure being formed in the first groove structure and having a second depth such that the first concave The groove structure has a first depth smaller than the second depth only at a plurality of support positions along the periphery capable of supporting the joined member in the vertical direction.
The substrate of claim 1 wherein the second groove structure further extends from at least a portion of the perimeter between the plurality of support locations to an exterior of the first groove structure.
The substrate according to claim 1 or 2, wherein the first depth is equal to or smaller than a thickness of the joined member.
The substrate according to claim 1, wherein the first groove structure has a square planar shape.
The substrate according to claim 4, wherein the plurality of support positions are positions at four corners of the first groove structure.
The substrate according to claim 2, wherein the first groove structure has a square planar shape, the plurality of support positions are positions at four corners of the first groove structure, and the A two groove structure extends from at least one side of the first groove structure to an exterior of the first groove structure.
The substrate according to claim 6, wherein the second groove structure extends from four sides of the first groove structure to an outside of the first groove structure and has a cross-shaped planar shape.
The substrate according to claim 7, wherein a width of the second groove structure is smaller than a width of the first groove structure, and a length of the second groove structure is larger than a length of the first groove structure width.
The substrate according to claim 1 or 2, wherein a heat transfer station for conducting heat from the joined member is disposed inside the second groove structure, and a top surface of the heat transfer station is at most The bottom of the first groove structure is flush.
The substrate according to claim 9, wherein the position of the heat transfer stage corresponds to a heat generating position of the joined member.
The substrate according to claim 10, wherein the planar shape of the heat transfer stage is one of a square, a rectangle, and a circle.
The substrate according to claim 1 or 2, wherein the member to be joined is a wavelength conversion chip.
The substrate according to claim 1 or 2, wherein the bonding material is a solder paste.
A method of forming a package structure using the substrate according to any one of claims 1 to 13, the method comprising:

Providing the substrate;

Printing the bonding material to the bonding surface of the joined component;

Mounting the joined component at the first groove structure of the substrate in such a manner that the bonding surface of the joined component faces the substrate;

Placing a weight on the engaged component;

The assembly including the substrate, the joined member, and the weight obtained at this time is placed in a vacuum eutectic furnace for welding to allow the bonding material to be in the second concave of the substrate Free flow in the groove structure;

After the welding is completed, the weight is removed.
A package structure, the package structure comprising:

The substrate according to any one of claims 1 to 13;

Jointed component;

A bonding material for bonding the joined component to the bonding surface of the substrate.