1261327 九、發明說明： 【發明所屬之技術領域】 本發明係有關於一種薄膜覆晶封裝方法，特別係有關 於一種薄膜覆晶封裝之晶片接合方法。 【先前技術】 薄膜覆晶封裝技術（COF，ChiP〇nFilm)可將驅動IC 及其電子零件直接接合在一薄膜（Film)上，省去傳統的印 • 刷電路板，達到更輕薄短小的目的，可運用於例如行動電 話、液晶顯示器等面積不大的產品上。 在1知薄膜覆晶封裝之晶片接合方法中，請參閱第1 圖，首先提供一壓合治具，該治具係包含有一壓合頭i i 及一壓焊座12,該壓合頭U與該壓焊座12係皆為硬質金 屬材料。提供一可撓性基板110，該可撓性基板11〇之一 上表面111係具有一線路層113及複數個連接墊114，該 線路層113上係形成有一覆蓋層115，防止該線路層113 瞻 X到污染。放置一晶片120於該壓焊座12上，該晶片120 之一主動面121上係設置複數個凸塊123，其中該些凸塊 123係包含金。 請參閱第2圖，接著熱壓合該可撓性基板11()與該晶 片120，加熱該壓合頭U與該壓焊座12並將該壓合頭n 下壓至該可徺性基板110之一下表面112，通常在薄膜覆 晶（cof)封裝製程中該壓合頭η之設定溫度係低於該壓焊 座12之設定溫度。該可撓性基板11〇之該些連接墊114 係對準於該晶片120之該些凸塊123，以電性導接該可撓 1261327 . * 性基板11 0與該晶片1 2 0。然而，該壓合頭11係為硬質材 料，其壓焊至該可撓性基板11 〇時，由於該可撓性基板η 〇 係為平坦狀，並且該晶片120上之該些凸塊123在製作形 成過程中會產生高度誤差，無法使得該些凸塊123之高度 完全一致，若該壓合頭11下壓之力量過大，容易使得先 接合之較高凸塊變形量過大而與相鄰凸塊產生電性短 路，若該壓合頭11下壓之力量不足，則該可撓性基板u〇 φ 之部分連接墊114與該晶片120之較低凸塊123無法完全 電性導接，進而產生假銲之情形。 【發明内容】 本發明之主要目的係在於提供一種薄膜覆晶封裝之 晶片接合方法，一壓合治具之一壓合頭係具有一軟質表 面，利用一熱壓合步驟使一可撓性基板電性導接至一晶 片，藉由該壓合頭之該軟質表面下壓至該可撓性基板，使 該些連接墊與該些凸塊完全電性導接，防止假焊之情形產 • 生。 依據本發明，一種薄膜覆晶封裝之晶片接合方法係提 供一壓合治具，該治具係包含有一壓合頭及一壓焊座，其 中該壓合頭係具有一軟質表面，並提供一可撓性基板，該 可撓性基板係具有一上表面及一下表面，該上表面係具有 一線路層及複數個連接墊，該線路層上係形成有一覆蓋 層’防止該線路層受到污染。放置一晶片於該壓焊座上， 該晶片係具有一主動面及一背面，該主動面上係設置複數 個凸塊，進行一熱壓合步驟，其係加熱該壓合頭與該壓焊 1261327 % ·工〒俊碌口」镜 ’其中該壓合頭 座並將該壓合頭下壓至該可撓性基板 性基板之該些連接墊與該晶片之該些 之溫度係低於該壓焊座之溫度。 【實施方式】 請參閱第3圖，本發明之一具體實施例係揭示一種薄 膜覆晶封裝之晶片接合方法，首先提供一壓合治具，該治 具係包含有一壓合頭21及一壓焊座22,其中該壓合頭^ • 係具有一軟質表面23，在本實施例中，該壓合頭21係為 具有一硬質本體24以及一軟膜25，該軟膜25之厚度係約 為1〇〇微米，以提供該軟質表面23，該軟膜25之材質係 可為塑膠或橡膠類，該壓焊座22係為硬質金屬材料。此 外，該壓合頭21亦可直接選用一種單件式軟質壓合材料。 提供一可撓性基板2 1 0，該可撓性基板2丨〇係具有一 上表面211及一下表面212，該上表面211係具有一線路 層213及複數個連接墊214，該線路層213上係形成有一 • t蓋層215，以防止該線路層213受到污染。放置一晶片 220於該壓焊座22上，該晶片22〇係具有一主動面221及 一背面222，該主動面221上係設置複數個凸塊223，其 中該些凸塊223係包含金。 請參閱第4圖，接著進行一熱壓合步驟，其係加熱該 壓合頭21與該壓焊座22並將該壓合頭21下壓至該可撓 性基板210，該壓合頭21之溫度係介於25〜2〇(rc，該壓 焊座22之溫度係介於360〜420。(：，其中該壓合頭21之溫 度係低於該壓焊座22之溫度。該可撓性基板21〇之該些 7 1261327 連接墊214係對準於該晶片22〇之該些凸塊223，以電性 導接忒可撓性基板2 1 〇之該些連接墊2丨4與該晶片之 該些凸塊223，由於該壓合頭21之該軟質表面23壓焊至 該可撓性基板210時，該軟質表面23能產生一適當之變 形以使該可撓性基板2 1 〇之該些連接墊2丨4係完全電性導 接至該晶片220之該些凸塊223，防止假銲之情形產生。 本發明之保護範圍當視後附之申請專利範圍所界定 2為準，任何熟知此項技藝者，在不脫離本發明之精神和 範圍内所作之任何變化與修改，均屬於本發明之保 圍。 【圖式簡單說明】 第1圖 習头薄膜覆曰曰封裝製程中晶片於熱壓合步驟前之 截面示意圖。 第2圖 習知薄膜覆晶封裝製程中晶片於熱壓合步驟時之 截面示意圖。 第3圖 依據本^明之具體實施例，在一種薄膜覆晶封 ^ 裝製程中一晶片於熱壓合步驟前之截面示意圖。 【主要元件符號說明】 第4圖&據本發明之一具體實施例，在該薄膜覆晶封裝 製程中該晶片於熱壓合步驟時之截面示意圖。 11 壓合頭 12 壓焊座 21 壓合頭 22 壓焊座 24 硬質本體 25 軟膜 110 可撓性基板 111 上表面 23軟質表面 下表面 8 1261327 113 線路層 114 連接墊 115 覆 蓋 層 120 晶片 121 主動面 122 背 面 123 凸塊 210 可撓性基板 211 上表面 212 下 表 面 213 線路層 214 連接墊 215 覆 蓋 層 220 晶片 221 主動面 222 背 面 223 凸塊BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film flip chip packaging method, and more particularly to a wafer bonding method for a film flip chip package. [Prior Art] The film flip chip packaging technology (COF, ChiP〇nFilm) can directly bond the driver IC and its electronic components to a film (Film), eliminating the need for a conventional printed circuit board to achieve a lighter, thinner and shorter purpose. It can be used in products such as mobile phones and liquid crystal displays. In the wafer bonding method of the film flip chip package, please refer to FIG. 1 . First, a press fixture is provided. The fixture comprises a press head ii and a pressure pad 12, and the press head U and The bonding pads 12 are all made of a hard metal material. A flexible substrate 110 is provided. The upper surface 111 of the flexible substrate 11 has a circuit layer 113 and a plurality of connection pads 114. The circuit layer 113 is formed with a cover layer 115 to prevent the circuit layer 113. Looking X to pollution. A wafer 120 is placed on the bonding pad 12, and a plurality of bumps 123 are disposed on one of the active faces 121 of the wafer 120, wherein the bumps 123 comprise gold. Referring to FIG. 2, the flexible substrate 11 () and the wafer 120 are then thermocompression-bonded, the bonding head U and the bonding pad 12 are heated, and the bonding head n is pressed down to the flexible substrate. The lower surface 112 of one of the 110 is generally set at a lower temperature than the set temperature of the bonding pad 12 in a film over-cladding (cof) packaging process. The connecting pads 114 of the flexible substrate 11 are aligned with the bumps 123 of the wafer 120 to electrically connect the flexible 1261327. The substrate 110 and the wafer 120. However, the press-fit head 11 is a hard material, and when it is pressure-bonded to the flexible substrate 11 , the flexible substrate η is flat, and the bumps 123 on the wafer 120 are There is a height error in the formation process, and the heights of the bumps 123 cannot be completely uniform. If the force of pressing the press head 11 is too large, the deformation of the higher bumps that are first joined is too large and the adjacent convexity is excessive. The block is electrically short-circuited. If the pressing force of the pressing head 11 is insufficient, the portion of the connecting pads 114 of the flexible substrate u〇φ and the lower bumps 123 of the wafer 120 cannot be electrically connected. The situation of false welding. SUMMARY OF THE INVENTION The main object of the present invention is to provide a wafer bonding method for a wafer flip chip package. A press-fit head has a soft surface, and a flexible substrate is used to make a flexible substrate. Conductively connecting to a wafer, the soft surface of the pressing head is pressed down to the flexible substrate, and the connecting pads are completely electrically connected to the bumps to prevent false soldering. Health. According to the present invention, a wafer bonding method for a wafer flip chip package provides a press fixture comprising a press head and a press pad, wherein the press head has a soft surface and provides a The flexible substrate has an upper surface and a lower surface. The upper surface has a circuit layer and a plurality of connection pads. The circuit layer is formed with a cover layer to prevent contamination of the circuit layer. Depositing a wafer on the bonding pad, the wafer has an active surface and a back surface, the active surface is provided with a plurality of bumps, and a thermal pressing step is performed, which heats the pressing head and the pressure welding 1261327 % · 〒 碌 」 」 ” ” ” ” ” ” ” ” ” ” ” ” 613 」 」 」 」 」 」 」 」 」 」 」 」 」 」 」 」 」 」 」 」 」 」 」 」 」 」 」 」 」 The temperature of the pad. [Embodiment] Referring to FIG. 3, an embodiment of the present invention discloses a wafer bonding method for a film flip chip package. First, a press fixture is provided. The fixture includes a press head 21 and a pressure. The solder joint 22, wherein the press head has a soft surface 23, in the embodiment, the press head 21 has a rigid body 24 and a soft film 25, and the thickness of the soft film 25 is about 1 The soft surface 23 is provided in a micron size, and the material of the soft film 25 may be plastic or rubber. The bonding pad 22 is made of a hard metal material. In addition, the press head 21 can also directly use a one-piece soft press material. A flexible substrate 2 10 is provided. The flexible substrate 2 has an upper surface 211 and a lower surface 212. The upper surface 211 has a circuit layer 213 and a plurality of connection pads 214. The circuit layer 213 A top layer 215 is formed on the upper layer to prevent contamination of the circuit layer 213. A wafer 220 is disposed on the bonding pad 22, the wafer 22 having an active surface 221 and a back surface 222. The active surface 221 is provided with a plurality of bumps 223, wherein the bumps 223 comprise gold. Referring to FIG. 4, a thermocompression bonding step is performed to heat the bonding head 21 and the bonding pad 22 and press the bonding head 21 down to the flexible substrate 210. The pressing head 21 is pressed. The temperature is between 25 and 2 〇 (rc, the temperature of the bonding pad 22 is between 360 and 420. (: wherein the temperature of the pressing head 21 is lower than the temperature of the bonding pad 22. The connecting pads 214 of the flexible substrate 21 are aligned with the bumps 223 of the wafer 22 to electrically connect the flexible pads 2 1 to the connecting pads 2丨4 and The soft surface 23 of the wafer 223 can be appropriately deformed to make the flexible substrate 2 1 The connection pads 2丨4 are completely electrically connected to the bumps 223 of the wafer 220 to prevent the occurrence of false soldering. The scope of protection of the present invention is defined by the scope of the appended patent application. Any changes and modifications made by those skilled in the art without departing from the spirit and scope of the invention belong to the present invention. Brief Description of the Drawings Fig. 1 is a schematic cross-sectional view of the wafer before the thermocompression bonding step in the film coating process of the first film. Fig. 2 is a schematic cross-sectional view of the wafer during the thermal compression bonding step in the conventional film flip chip packaging process. 3 is a schematic cross-sectional view of a wafer before a thermocompression bonding step in a film overmolding process according to a specific embodiment of the present invention. [Description of Main Components] FIG. 4 & For example, a cross-sectional view of the wafer during the thermal lamination step in the film flip-chip packaging process. 11 Pressing head 12 Bonding pad 21 Pressing head 22 Bonding pad 24 Hard body 25 Soft film 110 Flexible substrate 111 Surface 23 soft surface lower surface 8 1261327 113 circuit layer 114 connection pad 115 cover layer 120 wafer 121 active surface 122 back surface 123 bump 210 flexible substrate 211 upper surface 212 lower surface 213 circuit layer 214 connection pad 215 cover layer 220 wafer 221 Active surface 222 back 223 bump