CN103187381A - Lead frame packaging structure - Google Patents

Abstract

The invention discloses a lead frame packaging structure which comprises at least one bearing seat and at least one lead frame, wherein the bearing seats are used for bearing a chip, each lead frame comprises a first end which is electrically connected with a printed circuit board, a second end which is electrically connected with the chip and a lead part which is connected with the first end and the second end, and the height of the lead part is lower than the heights of the first end and the second end.

Description

Lead frame encapsulation structure

Technical field

The present invention relates to a kind of lead frame encapsulation structure, relate in particular to the lead frame encapsulation structure of the low electromagnetism of a kind of tool and low cross-talk.

Background technology

Integrated circuit (integrated circuit, IC) encapsulation can be according to the loading material of chip, be divided into leaded package (lead frame package), rigid plastics support plate encapsulation (laminate substratepackage), soft support plate encapsulation (tape package), and ceramic substrate encapsulation (ceramic package).Wherein, leaded package possesses features such as low cost and low speed signal transmission requirement (be inapplicable at the high speed transmission of signals interface, as DDR3-1333Mbps, HDMI or USB3).

Please refer to Fig. 1, Fig. 2 and Fig. 3, Fig. 1 is the vertical view of existing leadframe encapsulation structure 10 for schematic appearance, Fig. 2 of existing leadframe encapsulation structure 10, and Fig. 3 is the structural map of existing lead frame encapsulation structure 10.As shown in Figure 1, 2, leadframe encapsulation structure 10 comprises a plurality oflead frames 100 and chip 11.Lead frame 100 includesouter pin 102,interior pin 104 and wire portion 106.Wherein,outer pin 102 electrically connects printed circuit board (PCB) (being not shown among the figure),interior pin 104 electrically connectschip 11 by wire bonds mode (gold thread 103 as shown in Figure 2), andwire portion 106 is connected betweeninterior pin 102 and the outer pin 104.As shown in Figure 3, leadframe encapsulation structure 10 also includes theload bearing seat 12 ofcarries chips 11, and is used for the packing colloid (molding) 13 of coatedwire frame 100 andchip 11.

From the above, leadframe encapsulation structure 10 non-multilayer board architectures (multi-layer), therefore do not have reference ground plane (the reference ground plane) design on the picture printed circuit board (PCB), thereby have impedance Control difficulty, cross-talk (crosstalk) problem, and distribution network (power distributionnetwork, height circulation inductance value disappearances such as (loop inductance) PDN).For solving above-mentioned disappearance, in the prior art, leadframe encapsulation structure 10 is provided with an earth connection between eachlead frame 100, but this mode can reduce the quantity that arranges oflead frame 100, thereby causes the quantity of signal output (pin out) to reduce.

Summary of the invention

Therefore, main purpose of the present invention is to provide a kind of conducting wire frame structure, uses addressing the above problem.

The present invention discloses a kind of lead frame encapsulation structure, and this lead frame encapsulation structure includes: at least one load bearing seat is used for carrying a chip; And at least one lead frame, comprise one first end that electrically connects a printed circuit board (PCB), one second end that electrically connects this chip, and a wire portion that connects this first end and this second end; Wherein, the height of this wire portion is lower than the height of this first end and this second end.

Description of drawings

Fig. 1 is the outside drawing of an existing lead frame encapsulation structure.

Fig. 2 is the vertical view of an existing lead frame encapsulation structure.

Fig. 3 is the structural map of an existing lead frame encapsulation structure.

Fig. 4 is the schematic diagram of the embodiment of the invention one lead frame encapsulation structure.

Fig. 5 is arranged on the schematic diagram of printed circuit board (PCB) for the embodiment of the invention one lead frame encapsulation structure.

Fig. 6 is the schematic diagram of the embodiment of the invention one signal entrance loss.

Fig. 7 is the schematic diagram of the embodiment of the invention one signal reflex loss.

Fig. 8 is the schematic diagram of the embodiment of the invention one long-range cross-talk.

Fig. 9 is the schematic diagram that the embodiment of the invention one near-end crosstalk is disturbed.

Wherein, description of reference numerals is as follows:

10,40 lead frame encapsulation structure

100,400 lead frames

11,41 chips

12,42 load bearing seats

13,43 packing colloids

102,402 outer pins

104,404 interior pins

106,406 wire portions

103,403 gold threads

50 ground planes

Port 1 first end

Port 2 second ends

Port 3 the 3rd end

Port 4 the 4th end

The CL current cycle

Embodiment

Please refer to Fig. 4, Fig. 4 is the schematic diagram of the embodiment of the invention one lead frame encapsulation structure 40.Leadframe encapsulation structure 40 compriseslead frame 400,chip 41,load bearing seat 42 and packing colloid 43.Lead frame 400 includesouter pin 402,interior pin 404 and wire portion 406.Wherein,outer pin 402 electrically connects printed circuit board (PCB) (not being indicated among Fig. 4),interior pin 404 electrically connectschip 41 bygold thread 403, andwire portion 406 electrically connectsinterior pin 402 and outer pin 404.Load bearing seat 42 is used for carries chips 41.Packing colloid 43 is used for coatedwire frame 400 and chip 41.In this embodiment,outer pin 402 can be sea-gull aerofoil profile (Gull-Wing) pin.

It should be noted thatwire portion 406 height of the embodiment of the invention need be lower than the height ofouter pin 402 andinterior pin 404, to form thewire portion 406 of concave shape.Comparison diagram 3 and Fig. 4 can know thewire portion 406 of finding out the embodiment of the invention simultaneously, are the shapes that are to lower recess compared to existing wire portion 106.Other please refer to Fig. 5, and Fig. 5 is arranged on the schematic diagram of printed circuit board (PCB) for the leadframe encapsulation structure 40 of the embodiment of the invention.As shown in Figure 5, when leadframe encapsulation structure 40 is arranged on printed circuit board (PCB),wire portion 406 is compared to existingwire portion 106, more press close to theground plane 50 on the printed circuit board (PCB), therefore, signal flows and current cycle (current loop) CL that forms is concentrated in the below ofwire portion 406 and flows atwire portion 406, uses and reduces cross-talk (crosstalk).In addition, becausewire portion 406 is pressed close to theground plane 50 of printed circuit board (PCB), the electric field scope thatwire portion 406 produces also concentrates betweenwire portion 406 and theground plane 50, therefore can reduce the influence oflead frame 400 on every side, and reduce electromagnetic interference.In simple terms, the leadframe encapsulation structure 40 of the embodiment of the invention is to utilize theground plane 50 of printed circuit board (PCB) as the ground connection oflead frame 400, uses and reduces signal and electromagnetic interference.

Please refer to Fig. 6, Fig. 7, Fig. 8 and Fig. 9, Fig. 6 is the schematic diagram of the embodiment of the invention one signal entrance loss (Insertion Loss), Fig. 7 is the schematic diagram of the embodiment of the invention one signal reflex loss (ReturnLoss), Fig. 8 is the schematic diagram of the embodiment of the invention one long-range string news (Far-End Crosstalk), and Fig. 9 is the schematic diagram of embodiment of the invention near-end crosstalk news (Near-End Crosstalk).In Fig. 6, suppose that signal is that thefirst end Port 1 fromlead frame 400 transfers to the second end Port 2.As shown in Figure 6, compared to the structure of existinglead frame 100, the signal entrance loss of thelead frame 400 of the embodiment of the invention is a little less than the signal entrance loss of existing lead frame 100.In Fig. 7, compared to the structure of existinglead frame 100, thelead frame 400 of the embodiment of the invention also is lower than the signal reflex loss of existinglead frame 100 in the signal reflex loss of the first end Port 1.For instance, under frequency 3000MHz, the signal reflex loss late oflead frame 400 reduces 6dB approximately.In addition, in Fig. 8, suppose that signal is that thefirst end Port 1 fromlead frame 400 transfers to the second end Port 2.Anotherlead frame 400 ofadjacent wires frame 400 can be subjected to cross-talk in leadframe encapsulation structure 40; In anotherlead frame 400, the3rd end Port 3 of thefirst end Port 1 ofadjacent wires frame 400 is called near-end in string news phenomenon, and is called long-range in string news phenomenon from the4th end Port 4 of thefirst end Port 1 away from.As shown in Figure 8, compared to the structure of existinglead frame 100, thelead frame 400 of the embodiment of the invention is lower than the long-range cross-talk of existinglead frame 100 in long-range cross-talk.For instance, under frequency 1500MHz, long-range cross-talk reduces 10dB approximately.In addition, in Fig. 9, thelead frame 400 of the embodiment of the invention also is lower than existinglead frame 100 in the cross-talk of near-end.For instance, under frequency 1500MHz, near-end crosstalk is disturbed and is reduced 3dB approximately.

From the above, compared to thewire portion 106 of existinglead frame 100 for level connect inpin 104 withoutside pin 102, thereby can't arrange the ground plane of printed circuit, cause problems such as string news and electromagnetic interference, thewire portion 406 of thelead frame 400 of the embodiment of the invention connectsinterior pin 104 andouter pin 102 for concave shape,lead frame 400 can be arranged press close to ground plane, and then effectively reduce problems such as string news and electromagnetic interference.It should be noted that at encapsulating structure in appearance the leadframe encapsulation structure 40 of the embodiment of the invention can be identical with the outward appearance of existing lead frame encapsulation structure, and need not change the making mould of present lead frame, therefore can save cost of manufacture.For instance, after producinglead frame 100, can carry out punching press towire portion 106, to form thewire portion 406 to recessed folding.

In sum, the present invention proposes a kind of new lead frame encapsulation structure, and compared to known conducting wire frame structure, the lead frame of the embodiment of the invention is depressed the ground plane of printed circuit board (PCB), therefore can effectively reduce the circulation inductance value, to reduce problems such as string news, electromagnetic interference.

The above is the preferred embodiments of the present invention only, is not limited to the present invention, and for a person skilled in the art, the present invention can have various changes and variation.Within the spirit and principles in the present invention all, any modification of doing, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (4)

1. lead frame encapsulation structure includes:

At least one load bearing seat is used for carrying a chip; And

At least one lead frame comprises one first end that electrically connects a printed circuit board (PCB), one second end that electrically connects this chip, and a wire portion that connects this first end and this second end;

Wherein, the height of this wire portion is lower than the height of this first end and this second end.

2. lead frame encapsulation structure as claimed in claim 1 is characterized in that, this wire portion is to form the height that highly is lower than this first end and this second end by an impact style.

3. lead frame encapsulation structure as claimed in claim 1 is characterized in that, this first end is a sea-gull aerofoil profile pin.

4. lead frame encapsulation structure as claimed in claim 1 is characterized in that, this second end electrically connects this chip by a wire bonds mode.

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