Method of manufacturing a substrate, corresponding substrate and semiconductor device

Abstract

Embodiments of the present disclosure relate to a method of manufacturing a substrate, a corresponding substrate and a semiconductor device. A pre-molded leadframe includes a layered structure having an empty space therein and a first thickness, wherein a die pad has opposing first and second die pad surfaces. An insulating pre-mold material is molded onto the layered structure. The pre-mold material penetrates the empty space and provides a layered pre-mold substrate having the first thickness, wherein the first die pad surface remains exposed. The die pad has a second thickness that is less than the first thickness. One or more columnar structures are provided that protrude from the second die pad surface to a height equal to a difference between the first and second thicknesses. With the layered structure sandwiched between surfaces of a die, the first die pad surface and the columnar formations are in close proximity to the die surfaces. As a result, the die pad is effectively sandwiched between the clamping surfaces to counteract undesirable flashing of the pre-mold material on the first die pad surface.

Description

[0001] Priority requirements

[0002] This application claims priority to Italian Patent Application No. 102021000020555, filed on July 30, 2021, the entire contents of which are incorporated herein by reference to the fullest extent permitted by law. Technical Field

[0003] This specification relates to semiconductor devices.

[0004] One or more embodiments can be applied to semiconductor power devices used in the automotive, consumer electronics, computer, and various other applications.

[0005] Power supply units (PSUs) for servers, laptop chargers, phone chargers, and USB wall plugs are just a few examples of possible applications of this embodiment. Background Technology

[0006] Various semiconductor devices (such as power quad flat no lead (QFN) packages) benefit from the presence of insulated die pads, where the package lead frame is half-etched in the die pad area to create an insulating resin layer beneath the half-etched die pad.

[0007] Various problems may arise when manufacturing such pre-molded leadframes: for example, leadframe clamping during pre-molding may not be entirely effective because, at the semi-etched die pads, it is necessary to ensure that the metal (copper) in the leadframe structure is only a portion (half) of its initial thickness.

[0008] As a result, the molding tool contacts the front (top) surface of the die pad; however, the front (top) surface of the die pad is not supported on its rear or bottom surface.

[0009] Therefore, die pads may float in the molding tool in some way, and resin "flash" (i.e., resin smearing or leaking onto the die pad) may be generated on the front or top surface of the die pad that cannot be removed by de-flashing and / or polishing.

[0010] There is a need in this field to help solve the aforementioned problems. Summary of the Invention

[0011] One or more embodiments may relate to a method.

[0012] One or more embodiments may involve a corresponding substrate (lead frame).

[0013] One or more embodiments may relate to corresponding semiconductor devices.

[0014] One or more embodiments may provide a pre-molded QFN lead frame including sacrificial pillars to properly clamp semi-etched die pads to be embedded in pre-molded resin.

[0015] These sacrificial pillars can be removed during a subsequent half-etching step performed after the final leadframe molding to form, for example, a wettable side for wire bonding.

[0016] Advantageously, one or more embodiments may provide increased anchoring of the second die (encapsulation) to the pre-molded resin in the lead frame.

[0017] According to an embodiment, the pre-molded leadframe includes one or more semi-etched insulating die pads having support posts extending toward the rear or bottom surface of the leadframe.

[0018] Advantageously, these support pillars include a hollow central portion on the front or top side. Therefore, a final pre-molded leadframe comprising cavities in the form of through holes can be manufactured (e.g., for manufacturing QFN packages).

[0019] Therefore, the second molding (encapsulation) material can penetrate into these holes and come into contact with the premolding resin. Thus, strong coupling (adhesion) between the premolding resin and the encapsulation can be achieved even when different types and / or amounts of fillers are present in the premolding resin and the encapsulation. Attached Figure Description

[0020] One or more embodiments will now be described by way of example with reference to the accompanying drawings, wherein:

[0021] Figure 1A and Figure 1B This is an example of a step in the conventional manufacturing process of a pre-molded substrate (lead frame);

[0022] Figure 1C It is Figure 1A and Figure 1B A schematic diagram of the substrate obtained through the steps;

[0023] Figure 2A and Figure 2B This is an example of a step in the routine manufacturing process of a pre-molded substrate (lead frame) that includes semi-etched die pads;

[0024] Figure 2C It is usable Figure 2A and Figure 2B A schematic diagram of the substrate obtained through the steps;

[0025] Figure 3 It is reproduced at a magnified scale, as indicated by arrow III. Figure 2C A portion of the view;

[0026] Figure 4A and Figure 4B In order to eliminate such Figure 3 Examples of possible steps to try given the defects shown;

[0027] Figures 5A to 5F The steps in the embodiments of this specification are shown; and

[0028] Figure 6A and Figure 6B This is a perspective view from a relative viewpoint of the substrate structure according to an embodiment of this specification. Detailed Implementation

[0029] Unless otherwise specified, corresponding numbers and symbols in different figures usually refer to the corresponding parts.

[0030] The accompanying drawings are provided to clearly illustrate relevant aspects of the embodiments and are not necessarily drawn to scale.

[0031] The edges of features drawn in the attached figures do not necessarily indicate the end of the feature range.

[0032] In the following description, various specific details are shown to provide a thorough understanding of various examples of embodiments according to the description. Embodiments may be obtained without one or more specific details, or by utilizing other methods, components, materials, etc. In other instances, known structures, materials, or operations are not shown or described in detail so as not to obscure the various aspects of the embodiments.

[0033] References to "an embodiment" or "one embodiment" within the framework of this specification are intended to indicate that a particular configuration, structure, or feature described with respect to that embodiment is included in at least one embodiment. Therefore, phrases such as "in an embodiment," "in one embodiment," etc., that may appear at various points in this specification do not necessarily refer precisely to the same embodiment. Furthermore, specific configurations, structures, or features may be combined in any suitable manner in one or more embodiments.

[0034] The headings / references used herein are provided for convenience only and are not intended to limit the scope of protection or the scope of the embodiments.

[0035] Semiconductor devices include one or more semiconductor chips or dies disposed (attached) on a substrate such as a lead frame.

[0036] Plastic packages are commonly used for semiconductor devices. Such packages may include a lead frame that provides a base substrate comprising a conductive material (e.g., a metal such as copper) sized and shaped to accommodate a semiconductor chip or die and to provide pad connections (leads) for these chips or dies.

[0037] The term “lead frame” (or “lead box”) (see, for example, the USPC Combined Glossary of Terms) refers to a metal frame that provides support for an integrated circuit chip or die, and electrical leads that interconnect the integrated circuit in the die or chip to other components or contacts.

[0038] Leadframes are typically created using techniques such as photolithography. This technique involves etching foil or strips of metal material on the top and bottom sides to create various pads and leads.

[0039] Quadrature flat no-lead (QFN) is a family of semiconductor device packages that exhibits high growth rates in the semiconductor packaging region.

[0040] QFN is a flexible and inexpensive package type with a wide range of possible applications, and the number of pins can range from 2 pins (e.g., in the case of diodes) to 100 pins or more (e.g., in multi-row arrangements of digital integrated circuits).

[0041] It should be noted that the term "leadless" applied to QFN packages refers to the fact that QFN packages typically do not have leads that protrude radially from the package; the leads or pins are actually provided on the rear or bottom surface of the package.

[0042] The lead frame used as the substrate for mounting the QFN package is advantageously provided in a "pre-molded" form, wherein an insulating resin (e.g., epoxy resin) fills the empty space between the die pads and the leads.

[0043] Currently used pre-molded lead frames include electrically insulating resins such as epoxy resin, which are molded onto an engraved conductive (e.g., metal) layered structure, for example, using a flat molding tool.

[0044] The space left in the etched metal material (e.g., copper) is filled with pre-molded resin, and the resulting lead frame has the same total thickness as the original etched lead frame.

[0045] After pre-molding (e.g., curing the molding resin by heat or UV curing), deburring and coating processes can be applied to provide a clean top / bottom metal surface.

[0046] For example, wettable sides can be provided during a second etching step, which can be applied to a pre-molded leadframe to create a dedicated etched area.

[0047] Pre-molded leadframes offer various advantages in the process assembly flow (primarily in lead bonding and molding).

[0048] Pre-molded leadframes also offer design advantages, such as the multiple die pads and fairly complex lead routing (e.g., for multi-chip applications) being features of interest.

[0049] The pre-molded leadframe substrate can be fabricated using photolithography techniques that start with layers or strips of a metallic material (e.g., copper), which is etched at the top and bottom sides to create pads and die pads with leads.

[0050] Then, an insulating resin, such as epoxy resin, is molded (e.g., via transfer technology). During resin molding, a molding tool is used to clamp the lead frame, with the die surface positioned against the lead frame structure. Low-viscosity resins can be used to promote good flow and filling.

[0051] The pads (leads) and die pads largely eliminate die flash (i.e., die resin smearing or leakage onto the pad surface), where moderate resin bleed-out occurs locally. De-flaking and polishing processes can be applied after resin molding to obtain a clean metal surface (e.g., considering Ag or NiPdAu polishing).

[0052] Figures 1A to 1C The order is an illustrative example of the aforementioned sequence of steps.

[0053] Specifically, in Figures 1A to 1C In the figure, reference numeral 10 denotes a die pad included in an engraved conductive layered structure on a lead frame (substrate). Such an engraved structure has spaces therein that are initially empty and then filled with a pre-molded material 12 (e.g., a resin such as epoxy resin) that is molded onto the engraved conductive layered structure of the lead frame.

[0054] like Figure 1A and Figure 1B As shown – these can essentially be considered as partial cross-sectional views through the substrate (lead frame) 10 – the pre-molded material is supplied in a flowable state while the layered structure 10 is clamped between the planar clamping surfaces of the pre-molded tool, which includes a first (top) portion TP and a second (bottom) portion BP.

[0055] The planar clamping surfaces of the pre-molding tool (designated as TPS and BPS, respectively) are held at a distance D1 equal to the final required thickness of the lead frame (see...). Figure 1C ).

[0056] The pre-molded material 12, molded onto the layered structure 10 held in the pre-molding tool TP, BP, penetrates into the initially empty space in the engraved metal structure of the lead frame.

[0057] Therefore, a layered pre-molded substrate (lead frame) with the same thickness D1 as the layered structure is produced, wherein the front (top) surface 10A of the die pad 10 is exposed (i.e., uncovered) by the pre-molded material 12 (even after it has been cured, for example, via UV or thermal curing).

[0058] like Figures 1A to 1C The lead frame structure illustrated in the figure promotes good clamping between the planar clamping surfaces TPS and BPS, so that the pre-molded material 12 does not have significant "flash" at surface 10A.

[0059] Some edge resin oozing may occur on surface 10A, which can be removed by deburring and polishing steps to obtain a clean metal surface 10A suitable for semiconductor chip mounting.

[0060] like Figure 1C As can be seen, the engraved metal structure of the lead frame (e.g., die pad, such as 10) is exposed (i.e. remains uncovered) by pre-molded material 12 at the front or top surface 10A and at the rear or bottom surface (designated as 10B).

[0061] Various applications of pre-molded leadframes can benefit from the availability of insulated die pads.

[0062] The insulating die pads are exposed only on the front or top surface 10A (i.e., not covered by the pre-molding material), while the rear or bottom surface 10B is covered by the pre-molding material 12. Therefore, the die pads are electrically isolated at their rear or bottom surface embedded in the molding material 12.

[0063] exist Figures 2A to 2C The example illustrates this situation, which has already been combined with Figures 1A to 1C The parts or elements discussed are denoted by the same reference numerals in the accompanying drawings, so for the sake of brevity, the corresponding detailed descriptions will not be repeated.

[0064] In such Figures 2A to 2C In the illustrated case of insulating pad arrangement, at die pad 10, the engraved lead frame (metal) structure presents a recessed portion on the rear surface or bottom surface 10B.

[0065] At die pad 10, the engraved (metallic) structure of the leadframe has a second thickness D2, which is smaller than the general thickness D1 of the pre-molded leadframe (see...). Figure 2C (For reference only).

[0066] For example, in Figures 2A to 2C In the case illustrated, die pad 10 may be a “semi-etched” portion of a leadframe with a thickness D2, which is (at least approximately) half the thickness D1.

[0067] If the previously applied bonding is used when producing a pre-molded leadframe with such a recessed portion / reduced thickness (e.g., a semi-etched die pad 10), Figure 1A and Figure 1B If the same process is described, then the clamping between the clamping surfaces TPS and BPS of the clamping tool may not be completely effective.

[0068] In practice, in this case, the die pad 10 will have: its front or top surface 10A (the surface for receiving one or more semiconductor chips mounted thereon) fully abutting the first planar die surface TPS, and its rear surface or bottom surface 10B (opposite to the front or top surface 10A) arranged at a certain distance from the second planar die surface BPS (given by the difference between D1 and D2).

[0069] Therefore, the rear surface or bottom surface 10B of the die pad 10 will not be supported by the bottom BP of the molding tool, thus causing the die pad 10 to float and be exposed to unwanted displacement / bending.

[0070] like Figure 3 As illustrated in the magnified view, this can result in undesirable "flash" on the front or top surface 10A of the pre-molded material 12.

[0071] This is a defect that could very likely cause the substrate to be rejected as a defective product.

[0072] This defect cannot be removed by standard deburring and / or polishing steps.

[0073] In principle, this defect can be removed by grinding the front or top surface of the pre-molded lead frame, such as... Figure 4B As instructed by the G.

[0074] like Figure 4A As shown, the front or top surface of the pre-molded leadframe includes an insulating die pad 10 plus pads or leads 14 (intended to provide the final contact pins of the device package), and the pre-molded material 12 fills the empty spaces in the engraved metal structure (pads 10 and 14) of the leadframe.

[0075] It was found that this possible grinding was either impractical or ineffective.

[0076] In fact, the flash extends to the top surface or front surface 10A (see...). Figure 3 The thickness of the pre-molded material 12 on the surface can exceed 3 micrometers.

[0077] Therefore, grinding may unnecessarily reduce the thickness of the pre-molded leadframe. This, in turn, can lead to unwanted leadframe deformation / delamination and surface damage.

[0078] Even with measures such as providing shape-improving features like zigzag notches, these drawbacks cannot be eliminated.

[0079] Figures 5A to 5F An example of the steps is to overcome the disadvantages discussed above by using die pads 10 that are formed again in the recessed portion of the leadframe with a thickness D2, which is less than (e.g., half) the total thickness D1 of the leadframe.

[0080] like Figures 5A to 5F As described herein, one or more (sacrificial) pillar formations 100 are provided that protrude from the rear surface or bottom surface 10B of the die pad 10.

[0081] The column forming member 100 (only one is shown for simplicity) has a height equal to D1 minus D2, which is the difference between the first total thickness D1 of the pre-molded lead frame and the second smaller thickness D2 at the recessed portion (i.e., at the die pad 10).

[0082] Results (see Figure 5A and Figure 5B When the lead frame metal structure is clamped between clamping surfaces TPS and BPS, the front or top surface 10A will again abut against surface TPS, and the distal portion of the pillar forming 100 will similarly abut against the opposing clamping surface BPS. In this manner, when the pre-molded material 12 is molded onto it (e.g., Figure 5B As illustrated in the example, this facilitates proper clamping of the leadframe's sculpted metal structure (without die pads "floating").

[0083] In this way, unwanted flash (smearing) of the pre-molded material 12 on surface 10A can be effectively counteracted, resulting in a cleaner surface 10A of the die pad 10, free from obvious flash of the pre-molded material thereon.

[0084] Advantageously, column forming element 100 can be as follows Figure 5C and Figure 5D The order shown is removed.

[0085] For example, this can occur during an etching step (in a manner known to those skilled in the art) performed to provide wettable sides for soldering.

[0086] The etching step can (using conventional techniques) mask the bottom surface of the lead frame and perform (semi) etching by removing metal material at those locations where wettable sides are required.

[0087] The steps may involve applying a resist layer (for simplicity, on...) Figure 5C(As shown in the image and not referenced) is applied to the front or top surface of the lead frame. The purpose of the resin layer is to protect surface 10A from damage caused by acid erosion during the removal of columnar structure 100.

[0088] This approach can be extended to the location where columnar structures 100 are provided (as described above, one is shown for simplicity, but multiple columnar structures can be advantageously used).

[0089] As shown in the figure, the (blind) hole 100A can be advantageously provided at each of the positions where the pillar forming 100 is provided in the die pad 10.

[0090] like Figure 5A and Figure 5B As can be seen, the blind via 100A has an opening at the front of the top surface 10A of the die pad and a closed end at the rear or bottom surface 10B, wherein a support forming member 100 is provided at the rear or bottom surface 10B.

[0091] like Figure 5D As can be seen, removing the pillar forming member 100 causes the blind hole 100A to become a through hole extending between the opposing surfaces 10A and 10B of the die pad 10.

[0092] Figure 5E It is an example of a semiconductor chip or die 16 (one is shown for simplicity, but multiple chips may be provided) mounted on the front of the top surface 10A of the die pad 10.

[0093] This can be achieved via an attachment material (any type known to those skilled in the art, not shown in the figure).

[0094] A wire bonding pattern 18 may be formed to provide chip 16 and lead frame (see...) Figure 4A and 4B After the electrical connection between the conductive leads in 14) is completed, an encapsulation material 20, such as epoxy resin, can be molded onto the resulting structure to complete the semiconductor device encapsulation.

[0095] like Figure 5F As shown, the encapsulating material 20 (which is in a flowable state during molding) can penetrate into the through hole 100A, thereby advancing from the front or top surface 10A of the die pad 10 to the bottom or back surface 10B of the die pad 10 and onto the pre-molded material 12.

[0096] Since the pre-molded material 12 and the encapsulating material 20 are cured (e.g., via UV or thermal curing), this arrangement provides strong coupling of the encapsulation 20, as is typically required to both the die pad 10 and the pre-molded material 12, also when the resin materials 12 and 20 have different filler contents (type and amount of filler).

[0097] It should be noted that the blind hole (and subsequently the through hole) 100A will have a cross-sectional area that is at least smaller than the corresponding cross-sectional area of ​​the columnar structure 100 at its edges. As a result, once the columnar structure 100 is removed, it will leave an empty space in the material 12 of the hole 100A with a larger cross-sectional area.

[0098] Therefore, the encapsulation material 20 that penetrates into the hole 100A and reaches the pre-molded material 12 will eventually take the shape of an inverted T (or inverted mushroom), with its distal portion being larger than the stem portion that extends through the hole 100A.

[0099] As a result, once cured like the molding material 12, the package 20 will provide a robust formal coupling to anchor the materials 12 and 20, with the die pad 10 sandwiched between them.

[0100] Figure 6A and Figure 6B This describes a possible implementation of the sculpted conductive metal structure of the pre-molded lead frame on the structure prior to molding pre-molded material (e.g., 12) onto the conductive metal structure of the pre-molded lead frame.

[0101] The pillar forming element 100 is visibly disposed on the rear surface or bottom surface 10B of the die pad 10, while the blind hole 100A is disposed on the front surface or top surface 10A at a position corresponding to the position where the pillar forming element 100 is disposed.

[0102] The examples described herein provide temporary pillar formations (e.g., 100) connected to die pads 10 that require insulation.

[0103] The column forming member 100 produces a (partial) portion of the additional half-etched die pad with a metal material thickness D1, which promotes full clamping of the lead frame between the clamping surfaces TPS and BPS of the clamping tool.

[0104] In this manner, while the layered structures 10 and 14 are clamped between the planar clamping surfaces TPS and BPS of the pre-molding tools TP and BP, maintaining a distance equal to the first thickness D1, the first die pad surface 10A remains firmly against the first planar clamping surface TPS of the pre-molding tools TP and BP.

[0105] Therefore, it effectively offsets, such as Figure 2A and 2B The possible displacement of the "floating" die pad 10 under certain circumstances, and such Figure 3 The subsequent flash of the pre-molded material 12 on the surface 10A illustrated in the figure.

[0106] Therefore, the "clean" die pad surface 10A is exposed by the pre-molded material 12, which eliminates the flash on the die pad surface 10A.

[0107] Meanwhile, the columnar structure 100 protruding from the surface 10B of the second die pad (with a height equal to the difference between thickness D1 and thickness D2) will include a distal portion exposed by pre-molded material 12.

[0108] For example, such a pillar forming 100 can be removed by etching, which can occur during the processing steps used to form the wettable side for welding.

[0109] The resulting semiconductor device will include an engraved conductive layered structure 10, 14 having space and a first thickness D1.

[0110] The structure shown includes one or more die pads 10 and an insulating pre-molded material 12. The die pads 10 have a first die pad surface 10A and a second die pad surface 10B opposite each other, a second thickness D2 between the first die pad surface 10A and the second die pad surface 10B, and the insulating pre-molded material 12 is molded onto the layered structure 10, 14. The insulating pre-molded material 12 penetrates into a space in the base metal (e.g., copper) structure to provide a layered pre-molded substrate (lead frame). The layered pre-molded substrate has a (first) thickness D1 and includes the first die pad surface 10A exposed by the pre-molded material 12.

[0111] The semiconductor device according to the examples herein will also include one or more semiconductor chips or dies 16 mounted on a first die pad surface 10A, wherein: the first die pad surface 10A is free of (undesirably) pre-molded material 12 on which flash is applied, and the second die pad surface 10B is covered with insulating pre-molded material 12 to provide (desirably) insulation for the die pad 10.

[0112] As described above, the pillar forming element, for example 100, is advantageously formed with a hollow structure, which facilitates package flow during the final assembly of the package to complete the isolation of the die pads.

[0113] The insulating package 20 can actually be molded onto a layered pre-molded substrate (lead frames 10, 12, 14) and one or more semiconductor chips 16 mounted on the surface 10A of the first die pad.

[0114] As a result of removing the columnar structure 100, the die pad 10 will have a through hole 100A between the first die pad surface 10A and the second die pad surface 10B.

[0115] Therefore, package 20 will penetrate into these vias 100A and contact the pre-molded material 12 in the layered pre-molded substrate, thereby providing a strong anchor between material 12 and 20, with the lead frame sandwiched therebetween.

[0116] Without violating the basic principles and without departing from the scope of protection, the details and embodiments may vary significantly from what has been described for the purposes of this example only.

[0117] The claims form an integral part of the technical teachings provided herein regarding the embodiments.

[0118] The scope of protection is determined by the appended claims.

Claims

1. A method for manufacturing a semiconductor device, comprising: A sculpted conductive layer structure is provided, having a space in the sculpted conductive layer structure, wherein the sculpted conductive layer structure has a first thickness and includes at least one die pad, the at least one die pad having a first die pad surface configured to mount a mounted semiconductor chip and a second die pad surface opposite to the first die pad surface, wherein the at least one die pad has a second thickness between the first die pad surface and the second die pad surface, the second thickness being less than the first thickness; At least one pillar forming protrudes from the surface of the second die pad to the sculpted conductive layered structure, wherein each pillar forming has a height equal to the difference between the first thickness and the second thickness; The engraved conductive layered structure is clamped between a first planar clamping surface and a second planar clamping surface of a pre-molding tool, wherein the first planar clamping surface of the pre-molding tool abuts against the surface of the first die pad, and the second planar clamping surface of the pre-molding tool abuts against the distal portion of each pillar forming member, wherein the distance between the first planar clamping surface and the second planar clamping surface is substantially equal to the first thickness. Molding insulating pre-molding material to penetrate into the space of the sculpted conductive layered structure sandwiched between the first planar clamping surface and the second planar clamping surface of the pre-molding tool, and providing a layered pre-molding substrate having the first thickness and including the first die pad surface and the distal portion of each pillar forming exposed by the pre-molding material; as well as The at least one column forming element is removed after the molding of the insulating pre-molded material.

2. The method according to claim 1, further comprising: A blind via is provided in the surface of the first die pad, aligned with each pillar forming protruding from the surface of the second die pad, wherein removing at least one pillar forming causes the blind via to become a through-hole between the surfaces of the first die pad and the second die pad.

3. The method of claim 2, further comprising: A semiconductor chip is mounted on the surface of the first die pad, the surface of which is exposed by the pre-molding material in the layered pre-molded substrate; as well as After removing the at least one pillar forming member, an insulating package is molded onto the layered pre-molded substrate having the semiconductor chip mounted on the surface of the first die pad, wherein the insulating package penetrates into the via and contacts the pre-molded material in the layered pre-molded substrate.

4. The method according to claim 1, wherein the second thickness between the surface of the first die pad and the surface of the second die pad is approximately half of the first thickness.

5. The method of claim 1, wherein providing the sculpted conductive layered structure having spaces therein comprises: Etching layered metal materials.

6. A substrate, comprising: An etched conductive layer structure having a space, wherein the etched conductive layer structure has a first thickness and includes at least one die pad, the at least one die pad having a first die pad surface configured to mount a semiconductor chip and a second die pad surface opposite to the first die pad surface; The at least one die pad has a second thickness between the surface of the first die pad and the surface of the second die pad, the second thickness being less than the first thickness; At least one pillar forming element protrudes from the surface of the second die pad, and each pillar forming element has a height equal to the difference between the first thickness and the second thickness; as well as An insulating pre-molded material is molded onto the layered structure, wherein the pre-molded material penetrates into the space to provide a layered pre-molded substrate having the first thickness between a front surface and a rear surface, and including a first die pad surface exposed by the pre-molded material at the front surface; The surface of the second die pad is covered by the pre-molded material to provide insulation for the at least one die pad at the rear surface; The distal portion of each columnar member is exposed by the pre-molded material at the rear surface of the layered pre-molded substrate; and The at least one column forming member is removed after the molding of the insulating pre-molded material.

7. The substrate of claim 6, wherein the surface of the first die pad is freed from flash of pre-molded material thereon.

8. The substrate of claim 7, wherein the second thickness between the surface of the first die pad and the surface of the second die pad is approximately half of the first thickness.

9. A semiconductor device, comprising: An etched conductive layered structure having a space, the layered structure having a first thickness and including at least one die pad, the at least one die pad having a first die pad surface and a second die pad surface opposite to the first die pad surface, wherein the at least one die pad has a second thickness between the first die pad surface and the second die pad surface, the second thickness being less than the first thickness; An insulating pre-molded material is molded onto the layered structure, wherein the pre-molded material penetrates into the space and provides a layered pre-molded substrate having the first thickness between a front surface and a rear surface, and including a first die pad surface exposed by the pre-molded material at the front surface; as well as The semiconductor chip is mounted on the surface of the first die pad; The surface of the second die pad is covered by the pre-molded material to provide insulation for the at least one die pad at the rear surface; and At least one pillar forming element is removed after the molding of the insulating pre-molded material, the at least one pillar forming element protruding from the surface of the second die pad, and each pillar forming element having a height equal to the difference between the first thickness and the second thickness.

10. The semiconductor device of claim 9, wherein the surface of the first die pad is freed from flash of pre-molded material thereon.

11. The semiconductor device of claim 9, further comprising: Insulating encapsulation, molded onto the layered pre-molded substrate and the semiconductor chip mounted on the surface of the first die pad; The at least one die pad has at least one through hole, which extends between the surface of the first die pad and the surface of the second die pad; as well as The insulating package penetrates into the through-hole and contacts the pre-molded material in the layered pre-molded substrate.

12. The semiconductor device of claim 9, wherein the second thickness between the surface of the first die pad and the surface of the second die pad is approximately half the first thickness.

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