201221003 六、發明說明 【發明所屬之技術領域】 本發明關於電子元件之表面安裝方法，詳言之爲 設於印刷配線板之貫穿導孔正上方的安裝焊墊進行電 件之表面安裝的方法及使用該方法製作之印刷電路板 【先前技術】 近年來以行動電話爲代表之電子機器之小型化及 能化持續進展。伴隨此而要求將更小型化、高機能化 子元件安裝於印刷配線板。此種電子元件之一爲 (Chip Size Package) » CSP 通常爲具有以約 0.3 〜1 窄間距接合用之錫球的封裝元件，於印刷配線板上被 表面安裝。 配合電子元件之連接部之高密度化，印刷配線板 裝安裝焊墊部亦需要高密度。因此，可考慮於貫穿導 上方設置安裝焊墊部。 但是，習知於印刷配線板之貫穿導孔（through via)正上方設置安裝焊墊部，而提升安裝密度乃 者。 詳細說明該問題之前，先說明習知技術之印刷配 之構造、及電子元件對該印刷配線板之表面安裝方法 圖5表示具有貫穿導孔之印刷配線板之一例，表 層印刷配線板120之構成。圖5(a)表示具有貫穿 之多層印刷配線板120之平面圖，圖5(b)表示沿 ，在 子元 高機 之電 CSP .0mm 實施 之安 孔正 hole 困難 線板 〇 示多 導孔 圖5 201221003 (a )之A-A’線之端面圖。 首先，說明多層印刷配線板120之平面構造。 如圖5 ( a )所示，多層印刷配線板120之表面，除 開口部119A〜11 9E以外被光焊錫阻劑層115覆蓋。 於開口部119A〜119D之底面，設置電子元件之安裝 用的安裝焊墊部116A〜116D及貫穿導孔118A〜118D。 由圖 5(a) 、 （b)可知，安裝焊墊部116A〜116D，係 藉由鏟層披膜114分別電連接於貫穿導孔118A〜118D。 另外，於開口部119E之底面，設置安裝焊墊部116E，但 未設置貫穿導孔。該安裝焊墊部116E大多用於接合電子 元件之虛擬腳位。虛擬腳位係指不使用於實際之信號導 通，而用於保持被表面安裝於印刷配線板上之電子元件之 平行度。 另外，在露出開口部11 9A〜11 9E之底面的鍍層披膜 114，爲提升焊錫潤溼性而實施金鍍層等之表面處理。 以下說明多層印刷配線板120之斷面構造。 如圖5 ( b )所示，多層印刷配線板1 20之基本構造 爲，將2個電路基材、亦即，附加有覆蓋層之電路基材 108與電路基材113，介由接著劑層1〇9貼合之多層電路 基材。 附加有覆蓋層之電路基材108，係於電路基材104之 背面，貼合由聚醯亞胺薄膜1〇6(例如12μιη厚度），及 形成於其上之接著劑層105 (例如15 μιη厚度）構成之覆 蓋層107者。接著劑層105，例如爲丙烯基系或環氧系接 -6- 201221003 著劑構成。 電路基材104，係在可撓性絕緣基底材1〇1( 25μιη厚度之聚醯亞胺薄膜）之兩面，針對具有 102、103 (例如各爲12μιη厚度）之兩面銅箔積層板 由光加工手法將銅箔加工成爲特定圖案者。又，於光 手法，係藉由光阻劑層之形成、曝光、及顯像將阻劑 形成於銅箔上之後，以阻劑圖案爲遮罩進行銅箔之蝕 而形成具有特定圖案之銅箔（電路圖案）。 電路基材113，係在可撓性絕緣基底材110之兩 針對具有銅箔111、112之兩面銅箔積層板，藉由光 手法將銅箔加工成爲特定圖案者。 多層印刷配線板120之貫穿導孔（through-via) 〜11 8D，係在上述多層電路基材之特定位置形成貫 度方向之貫穿通孔（through-hole )，於該貫穿通孔 導電化處理及電解銅鑛層處理而形成之鍍層披膜114 如8μηι厚度）構成。貫穿導孔118A〜118D，係作爲 導電路之機能，用於電連接各層配線。貫穿通孔，係 NC鑽孔加工等形成例如Φ 150μπι之大小。 以下使用圖6Α、6Β說明習知技術之於上述多層 配線板120進行電子元件之表面安裝之方法。圖6Α 表示電子元件之表面安裝方法說明用之工程端面圖。 (1)首先，準備焊錫印刷用之金屬版（金屬遮 130。金屬版130，具有多層印刷配線板120之安裝 部 1 16Α〜1 16Ε及分別對應之複數開口部 1: 例如 銅箔 ，藉 加工 圖案 刻， 面， 加工 1 1 8 A 穿厚 實施 (例 層間 藉由 印刷 、6B 罩） 焊墊 3 1 ' 201221003 131、 · · · 0 如圖6A ( 1 )所示，以金屬版130之複數開口部 1 3 1、1 3 1、·..分別重疊於多層印刷配線板1 20之安裝 焊墊部11 6A〜116E的方式，將金屬版130載置於多層印 刷配線板120之上。 (2 )之後，如圖6A ( 2 )所示，將錫膏140積層於 金屬版130上之後，滑動刮版150進行焊錫印刷。如此而 於金屬版130之開口部131內部塡埋錫膏140。201221003 6. Technical Field [Technical Field] The present invention relates to a surface mounting method for an electronic component, and more particularly to a method for mounting a surface of an electrical component by mounting a solder pad disposed directly above a through-via of a printed wiring board Printed circuit board produced by the method [Prior Art] In recent years, the miniaturization and energyization of electronic devices represented by mobile phones have continued to progress. Along with this, it is required to mount a more compact and high-performance device element on a printed wiring board. One such electronic component is a Chip Size Package. The CSP is usually a packaged component having solder balls bonded at a narrow pitch of about 0.3 to 1 and is surface mounted on a printed wiring board. In order to increase the density of the connection portion of the electronic component, it is also required to have a high density in the printed wiring board mounting and soldering portion. Therefore, it is conceivable to provide a mounting pad portion above the through guide. However, it is conventional to provide a mounting pad portion directly above the through via of the printed wiring board to increase the mounting density. Before explaining this problem in detail, a structure of a conventional printing technique and a method of mounting an electronic component on the surface of the printed wiring board will be described. FIG. 5 shows an example of a printed wiring board having a through-via, and a surface printed wiring board 120. . Fig. 5(a) is a plan view showing a multilayer printed wiring board 120 having a through-hole, and Fig. 5(b) is a view showing a multi-hole pattern along an Ankong positive hole hard line plate implemented in a sub-element motor CSP.0 mm. 5 201221003 (a) End view of the A-A' line. First, the planar structure of the multilayer printed wiring board 120 will be described. As shown in Fig. 5 (a), the surface of the multilayer printed wiring board 120 is covered with the solder resist layer 115 except for the openings 119A to 11 9E. Mounting pad portions 116A to 116D and through holes 118A to 118D for mounting electronic components are provided on the bottom surfaces of the openings 119A to 119D. 5(a) and 5(b), the mounting pad portions 116A to 116D are electrically connected to the through vias 118A to 118D by the shovel layer mask 114, respectively. Further, a mounting pad portion 116E is provided on the bottom surface of the opening portion 119E, but a through hole is not provided. The mounting pad portion 116E is mostly used to bond the dummy pins of the electronic component. The virtual pin refers to the parallelism of the electronic components that are surface mounted on the printed wiring board, which is not used for actual signal conduction. Further, the plating mask 114 exposing the bottom surfaces of the openings 11 9 to 11 9E is subjected to surface treatment such as gold plating to improve solder wettability. The cross-sectional structure of the multilayer printed wiring board 120 will be described below. As shown in FIG. 5(b), the multilayer printed wiring board 120 has a basic structure in which two circuit substrates, that is, a circuit substrate 108 to which a cover layer is added, and a circuit substrate 113 are interposed via an adhesive layer. 1〇9 laminated multilayer circuit substrate. The circuit substrate 108 to which the cover layer is attached is attached to the back surface of the circuit substrate 104, and is laminated with a polyimide film 1〇6 (for example, a thickness of 12 μm), and an adhesive layer 105 (for example, 15 μm) formed thereon. Thickness) of the cover layer 107. The subsequent agent layer 105 is, for example, a propylene-based or epoxy-based -6-201221003 primer. The circuit substrate 104 is formed on both sides of a flexible insulating substrate 1〇1 (25 μm thick polyimide film) for photo-processing of a double-sided copper foil laminate having 102, 103 (for example, each 12 μm thickness) The method of processing copper foil into a specific pattern. Further, in the photo-method method, after the resist is formed on the copper foil by the formation, exposure, and development of the photoresist layer, the copper foil is etched with the resist pattern as a mask to form a copper having a specific pattern. Foil (circuit pattern). The circuit substrate 113 is formed of a two-sided copper foil laminate having copper foils 111 and 112 on both sides of the flexible insulating substrate 110, and the copper foil is processed into a specific pattern by photo-method. The through-via of the multilayer printed wiring board 120 is a through-hole formed at a specific position of the multilayer circuit substrate, and the through-hole is formed in the through-hole. And the plating layer 114 formed by the treatment of the electrolytic copper ore layer is composed of a thickness of 8 μm. The through holes 118A to 118D function as a conductive circuit for electrically connecting the wirings of the respective layers. Throughout the through hole, the NC drilling process or the like is formed to have a size of, for example, Φ 150 μm. Next, a method of performing surface mounting of an electronic component on the above-mentioned multilayer wiring board 120 will be described with reference to Figs. 6A and 6B. Fig. 6A shows an engineering end view for explaining the surface mounting method of the electronic component. (1) First, a metal plate for solder printing (metal cover 130, metal plate 130, mounting portion 1 having a multilayer printed wiring board 120, 16 Α to 1 16 Ε, and a plurality of corresponding opening portions 1 respectively: for example, copper foil, for processing Pattern engraving, surface, processing 1 1 8 A wearing thickness (example between layers by printing, 6B cover) pad 3 1 '201221003 131, · · · 0 As shown in Figure 6A (1), the number of metal plates 130 The metal plate 130 is placed on the multilayer printed wiring board 120 so that the openings 1 3 1 , 1 3 1 , . . . are superimposed on the mounting pad portions 117A to 116E of the multilayer printed wiring board 1 20, respectively. 2) Thereafter, as shown in Fig. 6A (2), after the solder paste 140 is laminated on the metal plate 130, the scratch plate 150 is subjected to solder printing. Thus, the solder paste 140 is buried inside the opening portion 131 of the metal plate 130.
(3 )之後，如圖6B ( 3 )所示，由多層印刷配線板 1 20取下金屬版1 30。如此則，錫膏構成之焊錫部（預備 焊錫層）141、141、· ··被形成於各安裝焊墊部11 6A 〜1 16E之上。 (4) 之後，準備在端子161設有錫球之電子元件 160 (例如CSP)。以使電子元件160之錫球載置於焊錫 部1 4 1上的方式，進行電子元件1 60與多層印刷配線板 1 20之定位後，將電子元件1 60搭載於多層印刷配線板 120 上。(3) Thereafter, as shown in Fig. 6B (3), the metal plate 1 30 is removed from the multilayer printed wiring board 120. In this manner, solder portions (pre-solder layers) 141, 141, ... formed of solder paste are formed on the respective mounting pad portions 11 6A to 16E. (4) Thereafter, an electronic component 160 (for example, CSP) of a solder ball is provided at the terminal 161. The electronic component 160 is mounted on the multilayer printed wiring board 120 after the electronic component 160 and the multilayer printed wiring board 120 are positioned such that the solder balls of the electronic component 160 are placed on the solder portion 141.
(5) 之後，針對搭載有電子元件160的多層印刷配 線板120進行加熱處理（回焊工程）。如此則，如圖6B (4)所示，藉由焊錫部141之錫膏及電子元件160之錫 球溶融而形成之焊錫接合部142，使電子元件160被接合 於安裝焊墊部116A〜116E上。 以下詳細說明上述習知技術之問題，亦即，在具有貫 穿導孔之多層印刷配線板1 20之貫穿導孔1 1 8 A〜1 1 8D上 201221003 無法設置安裝焊墊部之問題。 由上述表面安裝工程可知，在貫穿導孔正上方設置安 裝焊墊部時，回焊工程中溶融之焊錫流入貫穿導孔之貫通 孔。結果，焊錫接合部之焊錫量不足，而有連接不良之可 能性。另外，流入各個貫通孔之焊錫量不同，導致電子元 件對於多層印刷配線板成傾斜，無法維持平行度。此一問 題，不限定於此，多層印刷配線板120之構造，只要是具 有貫穿導孔之任意印刷配線板均會發生。 由上述理由可知，習知技術上，印刷配線板之安裝焊 墊部即使犧牲安裝密度，通常也是避開貫穿導孔正上方而 設置。 另外，習知被提案於貫穿導孔正上方進行電子元件之 表面安裝之方法（專利文獻1)。於該方法，首先，係於 貫穿導孔（實施鍍層後之貫穿導孔17)正上方之安裝焊 墊部（焊錫·焊墊12 )上印刷錫膏。之後，進行加熱處 理，將溶融之錫膏引入貫穿導孔之之貫穿通孔內，於貫穿 通孔內固化。重複該預備焊接工程，使焊錫完全塡充於貫 穿通孔內。之後，使安裝焊墊部平坦化之後，安裝電子元 件。 此方法之問題點在於，直至安裝電子元件爲止需要重 複進行預備焊錫工程，工程變爲複雜，生產性降低。另 外，對印刷配線板提供複數次之熱損傷，而有可能產生各 種不良（貫穿導孔之龜裂、絕緣樹脂膨脹、剝離等）。 近年來，考慮到環境問題而有增加使用無鉛焊錫之情 -9- 201221003 況，和共晶焊錫比較，無鉛焊錫之潤溼性不佳。因此，使 用無鉛焊錫時，焊錫同樣塡充於全部貫穿通孔內實際上有 極大困難。 其他之表面安裝方法可考慮使用有底導孔，例如專利 文獻2揭示，具有有底之導孔（肓孔（blind via hole) 30)，可以膏密度安裝之增層型（build up type)多層印 刷配線板。有底導孔時無焊錫之流出，因此於盲孔30正 上方比較容易安裝電子元件。 但是，增層型多層印刷配線板之製造通常需要較多工 時及材料。另外，有底導孔需要藉由具備詳細條件設定之 雷射加工形成，難以藉由NC鑽孔加工等予以形成。 如上述說明，習知上被要求能兼顧生產性及信賴性， 而且能在設於貫穿導孔正上方的安裝焊墊部進行電子元件 之安裝之方法。 [習知技術文獻] [專利文獻] 專利文獻1 :特公平7-1 12109號公報 專利文獻2 :特開2004-200260號公報 【發明內容】 (發明所欲解決之課題） 本發明依據上述技術之認識而完成，目的爲提供表面 安裝方法，其可在不損及生產性與信賴性情況下，在設於 貫穿導孔正上方的安裝焊墊部進行電子元件之表面安裝， -10- 201221003 以及使用該方法製作之印刷電路板。 (用以解決課題的手段） 依據本發明一態樣提供之電子元件之表面安裝方法， 係在設於印刷配線板之貫穿導孔正上方的安裝焊墊部進行 電子元件之表面安裝者；其特徵爲：準備：熱膨脹係數爲 上述電子元件之熱膨脹係數與上述印刷配線板之熱膨脹係 數之間之値的蓋體；以對上述貫穿導孔之貫穿通孔實施加 蓋的方式，使上述蓋體載置於上述安裝焊墊部；藉由進行 焊錫印刷，而使埋設上述蓋體用的焊錫部形成於上述安裝 焊墊部；以使上述電子元件之連接部載置於上述焊錫部之 上的方式，將上述電子元件搭載於上述印刷配線板之上； 對搭載有上述電子元件的上述印刷配線板進行加熱處理。 依據本發明另一態樣提供之印刷電路板，其特徵爲具 備：印刷配線板，其具有進行層間連接之貫穿導孔；焊錫 接合部，設於上述貫穿導孔之貫穿通孔之正上方；蓋體， 用於對上述貫穿導孔之貫穿通孔加蓋，被埋設於上述焊錫 接合部內；及電子元件，介由上述焊錫接合部被安裝於上 述印刷配線板；上述蓋體之熱膨脹係數爲，上述電子元件 之熱膨脹係數與上述印刷配線板之熱膨脹係數之間之値。 【實施方式】 以下參照圖面說明本發明之實施形態。各圖中具有同 等機能之構成要素附加同一符號，而省略同一符號之構成 -11 - 201221003 要素之詳細說明。 首先，使用圖1說明貫穿導孔正上方設有安裝焊墊部 之多層印刷配線板之製造方法。 (1)準備在可撓性絕緣基底材1A (例如25μιη厚之 聚醯亞胺薄膜）之兩面具有銅箔2Α及銅箔3Α (各爲例如 12μιη厚）的可撓性之兩面銅箔積層板。如圖1(1)所 示，使用光加工手法將銅箔2Α加工成爲特定之電路圖 案，製作增層用之電路基材4Α。 (2 )接著，準備在可撓性絕緣基底材1Β (例如 25 μπι厚之聚醯亞胺薄膜）之兩面具有銅箔2Β及銅箔3Β (各爲例如12 μιη厚）的可撓性之兩面銅箔積層板。和電 路基材4Α之情況同樣，使用光加工手法將銅箔3Β加工 成爲特定之電路圖案，製作如圖1(2)所示增層用之電路基 材4Β。 (3)接著，由圖1(3)可知，在電路基材4Β之背 面（圖中下側）貼合覆蓋層5，製作附加有覆蓋層之電路 基材6。該覆蓋層5，係於絕緣薄膜5a (例如12μηι厚之 聚醯亞胺薄膜）之上，形成丙烯基系或環氧系接著材構成 之接著劑層5b者（例如15ym厚）。 (Ο接著，如圖1(3)所示，進行電路基材4A與 附加有覆蓋層之電路基材6之定位之後，介由丙烯基系或 環氧系接著材構成之接著劑層7予以積層，而製作積層電 路基材8 * (5 )接著，如圖1 ( 4 )所示，藉由NC鑽孔加工於 -12- 201221003 積層電路基材8之特定位置形成貫穿通孔9 ( φ 150μιη) 。貫穿通孔9之直徑係考慮貫穿通孔9與搭載之電子元件 之連接部之形狀間之平衡而決定。通常，孔徑小時加工成 本容易變高，孔徑大時對之後搭載之電子元件之安裝高度 有影響。因此，貫穿通孔9之直徑設爲例如100〜300 μιη 範圍內。 貫穿通孔9，不限定於NC鑽孔加工，亦可藉由各種 雷射（UV-YAG雷射、碳酸雷射、激發雷射等）之雷射加 工予以形成。 (6) 接著，由圖1(5)可知，對貫穿通孔9實施導 電化處理之後，藉由實施電解銅鍍層而於積層電路基材8 之外層、以及貫穿通孔9之內壁形成鍍層披膜10(例如 8 μιη厚）。如此則，可獲得進行層間連接之貫穿導孔 1 1 〇 (7) 接著，藉由光加工手法將積層電路基材8之外 層之導電膜（銅箔+鍍層披膜）加工成爲特定圖案，於積 層電路基材8之兩面形成外層電路圖案12Α、12Β。 本工程使用之光加工手法所使用之光阻劑，較好是使 用具有可將貫穿通孔9掩蔽（tenting )之厚度（例如 2〇μιη厚）之乾薄膜阻劑。另外，亦可使用液狀阻劑或電 著阻劑，亦可保護貫穿導孔1 1。 (8) 接著，如圖1(5)所示，在需要絕緣保護之區 域形成光焊錫阻劑層1 3。於光焊錫阻劑層1 3形成開口部 15，由該開口部15之底面可使安裝焊墊部14(包含貫穿 -13- 201221003 導孔1 1 )露出。 之後’對露出開口部15之鑪層披膜10實施金鍍層等 之表面處理，進行外形加工，而獲得具有貫穿導孔之多層 印刷配線板1 6。 圖2 (a)表示上述方法製作之多層印刷配線板16之 平面圖。圖2(b)爲沿圖2(a)之A-A’線之端面圖。 由圖2(a) 、2(b)可知，多層印刷配線板16之安 裝焊墊部14，係設於貫穿導孔11正上方。如此則，和上 述多層印刷配線板1 20比較，多層印刷配線板1 6之安裝 焊墊部之配置密度可以提升，可對應於膏密度安裝。 以下使用圖3A〜3C說明於該多層印刷配線板16進 行電子元件之表面安裝的方法。 (1)首先，準備焊錫印刷用之金屬版（金屬遮罩） 20。金屬版20具有多層印刷配線板16之安裝焊墊部 14、1 4、. · ·及分別對應之開口部21、2 1 · _ .。 如圖3A ( 1 )所示，以使金屬版20之開口部21、 2 1 ··.分別重疊於多層印刷配線板1 6之安裝焊墊部 14、14、.··的方式，將金屬版20載置於多層印刷配 線板1 6之上。 金屬版20之開口部2 1之大小，係作爲如後述說明之 1個蓋體30通過之程度之大小。亦即，開口部21之直 徑，係大於球狀蓋體30之直徑大。與此同時，爲防止2 個蓋體30進入1個開口部21，較好是將開口部21之直 徑設爲未滿蓋體30之直徑之2倍。 -14· 201221003 (2)接著，如圖3A(2)所示，以金屬構成之 蓋體30實施貫穿導孔11之貫穿通孔之加蓋的方式， 體30載置於安裝焊墊部14之各個。 具體言之爲，於金屬版20上沈積複數個蓋體 30、·..之後，使刮板40滑動掃描金屬版20之上 使1個個蓋體30掉落至金屬版20之開口部21內部 住貫穿導孔1 1之貫穿通孔。由貫穿導孔1 1之下部側 空氣吸附而將蓋體30固定。 蓋體 30之直徑設爲較貫穿導孔11之直徑 130μπ〇大10〜20 μιη之値。蓋體30之大小（直徑） 確保電子元件之平行度而較好是統整爲一定値。 (3 )接著，如圖3Β ( 3 )所示，將錫膏50沈積 屬版20上之後，滑動刮板40而進行焊錫印刷。如此 錫膏50埋入金屬版20之開口部21內部之同時，開 21內之蓋體30被埋設於錫膏50內而固定。 (4) 接著，如圖3Β (4)所示，將金屬版20由 印刷配線板1 6取下。如此則，埋設有蓋體3 0之焊 (預備焊錫層）5 1、5 1、·..分別被形成於安裝焊 14、 14、 · · ·之上。 (5) 接著，準備表面安裝用之電子元件60 ( CSP) ’以使電子元件60之連接部（電子元件60之 61、或設於端子61上之錫球）載置於焊錫部51的方 進行電子元件60與多層印刷配線板1 6之定位。之後 電子元件60搭載於多層印刷配線板丨6上。 球狀 將蓋 30、 面， ，堵 進行 (約 ，爲 於金 而使 口部 多層 錫部 墊部 例如 端子 式， ，使 -15- 201221003 (6)接著，對搭載有電子元件60之多層印刷配線板 1 6進行加熱處理（回焊工程）。如此則，如圖3 C ( 5 )所 示，焊錫部51之錫膏溶融而形成焊錫接合部52。藉由該 焊錫接合部52使電子元件60接合於多層印刷配線板16 之安裝焊墊部14上。 本工程中，蓋體30係作爲貫穿導孔11之貫穿通孔之 蓋部之機能，因此，溶融之焊錫不會流入貫穿通孔。如此 則，構成焊錫接合部52之焊錫量不會減少，焊錫接合部 52之信賴性可以提升之同時，可維持電子元件60對多層 印刷配線板1 6之平行度。 另外，蓋體30爲球體，其頂部成爲一定之高度，電 子元件60之安裝高度（stand-off)呈穩定，更能確保平 行度。 經由上述工程，可以獲得在設於貫穿導孔1 1正上方 之安裝焊墊部14，被安裝有電子元件60的多層印刷電路 板70。 如圖3C ( 5 )所示，多層印刷電路板70，係介由設於 貫穿導孔11之貫穿通孔正上方之焊錫接合部52，而具由 安裝於多層印刷配線板16之電子元件60。另外，蓋體 30，係埋設於焊錫接合部52內，堵住貫穿導孔11之貫穿 通孔。 如上述說明，依據本實施形態，在不損及生產性及信 賴性之情況下’可對設於貫穿導孔11正上方之安裝焊墊 部，進行電子元件之表面安裝。另外，依據本實施形態， -16- 201221003 可以提供可安裝窄間距之電子元件，焊錫接合部之信賴性 變高，而且電子元件之平行度良好的印刷電路板。 又’於上述說明中，蓋體30之材質爲金屬，但本發 明不限定於此，亦即蓋體30之材質，只要是在回焊工程 溶融而不失去作爲蓋體機能者即可。因此，可爲樹脂等之 絕緣體。但是，就焊錫潤溼性觀點而言，蓋體之表面較好 是金屬。因此，以於樹脂構成之核心體實施鍍層處理，於 表面形成有導電披膜（例如Ni/Au鍍層）之樹脂核心作爲 蓋體使用亦可。 爲緩和作用於安裝有電子元件之印刷配線板（印刷電 路板）之應力，而將蓋體材料之熱膨脹係數設爲電子元件 之熱膨脹係數與印刷配線板之熱膨脹係數之中間値亦可。 以具有此種熱膨脹係數之樹脂作爲蓋體30之材料使用 時，安裝之電子元件60與多層印刷配線板1 6之間之熱膨 脹差引起之應力，可以被樹脂之彈性緩和。 又蓋體30只需設於正上方成爲安裝焊墊部之貫穿導 孔上即可，無須設於正上方不成爲安裝焊墊部之貫穿導孔 上。如上述說明，藉由僅於必要位置配置蓋體，可節省製 造工程。 又，如上述說明，蓋體30之形狀雖設爲球狀，但本 發明不限定於此，亦即，蓋體3 0之形狀只要能覆蓋貫穿 導孔之貫穿通孔即可，例如亦可爲橢圓球狀之蓋體30A (參照圖4(a))，或圓盤形狀之蓋體30B (參照圖4 (b) ) 〇 -17- 201221003 其他，和球體同樣更能確保電子元件之平行度之形 狀，可由對貫穿通孔加蓋的圓盤體30C1，及和該圓盤體 30C1正交的柱狀體30C2構成（參照圖4(c))之蓋體 3 0C。此情況下，柱狀體30C 2之長度較好是大於開口部 15之直徑。 又，本發明之電子元件之安裝方法，不限定於上述多 層印刷配線板16，可以適用於具備在貫穿導孔正上方設 有安裝焊墊部之構成的任意之印刷配線板。 業者可依據上述記載想到本發明之追加效果或各種變 形例，但本發明不限定於上述溼蝕刻。在不脫離申請專利 範圍所規定內容及其均等物所導出知本發明之槪念思想及 趣旨範圍內，可作各種追加、變更及部分刪除。 (發明效果） 依據彼等特徵，本發明可獲得以下效果》 將用於對上述貫穿導孔之貫穿通孔加蓋的蓋體，載置 於貫穿導孔之貫穿通孔上，形成埋設上述蓋體之焊錫部 (預備焊錫層）。如此則，回焊工程時蓋體會堵住貫穿通 孔，溶融之焊錫不會流入貫穿通孔內。因此，構成接合部 之焊錫量減少，可以提升焊錫接合部之信賴性之同時，可 維持電子元件對印刷配線板之平行度。 【圖式簡單說明】 圖1表示貫穿導孔正上方具有安裝焊墊部之多層印刷 -18- 201221003 配線板之製造方法說明用之工程端面圖。 圖2(a)表示貫穿導孔正上方設有安裝焊墊部之印 刷配線板之平面圖，（b )爲沿（a )之A-A’線之端面 圖。 圖3A表示本發明實施形態之電子元件之表面安裝方 法之工程端面說明圖。 圖3B表示接續圖3A之本發明實施形態之電子元件 之表面安裝方法之工程端面說明圖。 圖3C表示接續圖3B之本發明實施形態之電子元件 之表面安裝方法之工程端面說明圖。 圖4表示變形例之蓋體被載置於貫穿通孔上之印刷配 線板之端面說明圖。 圖5(a)表示具有和貫穿導孔分離設置之安裝焊墊 部之印刷配線板之平面圖，（b)爲沿（a)之A-A’線之 端面圖。 圖6A表示習知技術之電子元件之表面安裝方法工程 端面說明圖。 圖6B表示接續圖6A之習知技術之電子元件之表面 安裝方法工程端面說明圖。 【主要元件符號說明】 ΙΑ、1B、101、110:可撓性絕緣基底材 2A ' 2B ' 3A ' 3B、102、103、111、112：銅箱 4A、4B、1 04、1 1 3 :電路基材 -19- 201221003 5、 107 :覆蓋層 5a :絕緣薄膜 5 b、1 0 9 :接著劑層 6、 108:附加有覆蓋層之電路基材 7、 105 :接著劑層 8 :積層電路基材 9 :貫穿通孔 10、1 14 :鍍層披膜 1 1 :貫穿導孔 12A、12B:外層電路圖案 1 3、1 1 5 :光焊錫阻劑層 14 :安裝焊墊部 1 5 :開口部 1 6、1 2 0 :多層印刷配線板 20、130:金屬版（金屬遮罩） 2 1、1 3 1 :開口部 30 、 30A 、 30B 、 30C ：蓋體 30C1 :圓盤體 30C2 :柱狀體 4 0、1 5 0 :刮板 5 0、1 4 0 :錫膏 51、 141:焊錫部（預備焊錫層） 52、 142 :焊錫接合部 60、160:電子元件 -20- 201221003 6 1、1 6 1 :端子 70:多層印刷電路板 106 :聚醯亞胺薄膜 116E :安裝焊墊部 貫穿導孔 119E :開口部 1 1 6A、1 1 6B、1 1 6C、1 1 6D、 1 1 8 A、1 1 8B、1 1 8C、1 1 8D ： 119A ' 119B、 119C、 119D、 -21 -(5) Thereafter, the multilayer printed wiring board 120 on which the electronic component 160 is mounted is subjected to heat treatment (reflow process). As a result, as shown in FIG. 6B (4), the solder joint portion 142 formed by melting the solder paste of the solder portion 141 and the solder ball of the electronic component 160 causes the electronic component 160 to be bonded to the mounting pad portion 116A to 116E. on. The problem of the above-mentioned conventional technique will be described in detail below, that is, the problem of mounting the pad portion cannot be set on the through-holes 1 1 8 A to 1 8 8D of the multilayer printed wiring board 120 which penetrates the via hole. According to the surface mounting work described above, when the mounting pad portion is provided directly above the through hole, the molten solder in the reflow process flows into the through hole penetrating the via hole. As a result, the amount of solder in the solder joint portion is insufficient, and there is a possibility of poor connection. Further, the amount of solder flowing into each of the through holes is different, and the electronic component is inclined with respect to the multilayer printed wiring board, and the parallelism cannot be maintained. This problem is not limited to this, and the structure of the multilayer printed wiring board 120 may occur as long as it is any printed wiring board having a through-via. From the above reasons, it is known that the mounting pad portion of the printed wiring board is usually disposed so as to avoid the mounting density immediately above the through-hole. Further, a method of mounting the surface of an electronic component directly above the via hole has been proposed (Patent Document 1). In this method, first, solder paste is printed on a mounting pad portion (solder/pad 12) directly above the via hole (through via hole 17 after plating). Thereafter, heat treatment is performed to introduce the molten solder into the through-holes penetrating the via holes and solidify in the through-holes. This preliminary welding process is repeated so that the solder is completely filled in the through hole. After that, the mounting pad portion is planarized, and then the electronic component is mounted. The problem with this method is that the preparatory soldering process needs to be repeated until the mounting of the electronic components, and the engineering becomes complicated and the productivity is lowered. In addition, the printed wiring board is provided with a plurality of thermal damages, and various defects (cracks through the via holes, expansion of the insulating resin, peeling, etc.) may occur. In recent years, the use of lead-free solder has been increased in consideration of environmental issues. -9- 201221003, the wettability of lead-free solder is poor compared with eutectic solder. Therefore, when using lead-free solder, it is actually extremely difficult for the solder to be filled in all of the through holes. Other surface mounting methods may consider the use of a bottomed via, as disclosed in Patent Document 2, having a bottomed via hole 30, which can be installed in a paste density. Printed wiring board. When there is a bottom guide hole, there is no solder outflow, so it is easier to mount the electronic component directly above the blind hole 30. However, the manufacture of build-up multilayer printed wiring boards generally requires more man-hours and materials. Further, the bottomed via hole needs to be formed by laser processing with detailed condition setting, and it is difficult to form it by NC drilling processing or the like. As described above, it is conventionally required to perform productivity and reliability, and to mount the electronic component in the mounting pad portion provided directly above the through hole. [PRIOR ART DOCUMENT] [Patent Document 1] Patent Document 1: Japanese Patent Publication No. Hei No. Hei. No. 2004-200260 (Patent Document) The purpose of the invention is to provide a surface mounting method for surface mounting of electronic components in a mounting pad portion directly above the through hole without damaging productivity and reliability, -10- 201221003 And a printed circuit board produced using the method. (Means for Solving the Problem) A surface mounting method for an electronic component according to an aspect of the present invention is to mount a surface of an electronic component on a mounting pad portion provided directly above a through-via of a printed wiring board; The method is characterized in that: a cover body having a thermal expansion coefficient between a thermal expansion coefficient of the electronic component and a thermal expansion coefficient of the printed wiring board; and the cover body is covered by a through hole of the through-via hole Loading the soldering pad portion; forming a solder portion for embedding the lid body on the mounting pad portion by solder printing; and placing the connecting portion of the electronic component on the solder portion In the embodiment, the electronic component is mounted on the printed wiring board, and the printed wiring board on which the electronic component is mounted is subjected to heat treatment. A printed circuit board according to another aspect of the present invention includes: a printed wiring board having a through via for interlayer connection; and a solder joint portion directly above the through via of the through via; a cover body for covering the through hole of the through hole and embedded in the solder joint portion; and an electronic component mounted on the printed wiring board via the solder joint portion; the thermal expansion coefficient of the cover body is The coefficient of thermal expansion between the electronic component and the thermal expansion coefficient of the printed wiring board. [Embodiment] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The components having the same function in the respective drawings are denoted by the same reference numerals, and the same symbols are omitted. -11 - 201221003 Detailed description of the elements. First, a method of manufacturing a multilayer printed wiring board having a mounting pad portion directly above the via hole will be described with reference to Fig. 1 . (1) A flexible two-sided copper foil laminate having copper foil 2 turns and copper foil 3 turns (each of which is, for example, 12 μm thick) on both sides of a flexible insulating base material 1A (for example, a 25 μm thick polyimide film) . As shown in Fig. 1 (1), the copper foil 2 is processed into a specific circuit pattern by a photo-processing method, and a circuit substrate 4 for layer formation is produced. (2) Next, two sides of the flexible insulating base material 1 (for example, a 25 μm thick polyimide film) having two sides of a copper foil 2 Β and a copper foil 3 Β (each of which is, for example, 12 μm thick) are prepared. Copper foil laminate. Similarly to the case of the circuit substrate 4, the copper foil 3 is processed into a specific circuit pattern by a photo-processing method, and a circuit substrate 4A for layer formation as shown in Fig. 1 (2) is produced. (3) Next, as is clear from Fig. 1 (3), the cover layer 5 is bonded to the back surface (lower side in the figure) of the circuit substrate 4, and the circuit substrate 6 to which the cover layer is attached is produced. The cover layer 5 is formed on the insulating film 5a (e.g., a 12 μm thick polyimide film) to form an adhesive layer 5b of an acryl-based or epoxy-based adhesive material (e.g., 15 μm thick). (Ο), as shown in Fig. 1 (3), after the circuit substrate 4A and the circuit substrate 6 to which the coating layer is attached are positioned, the adhesive layer 7 composed of an acryl-based or epoxy-based adhesive material is applied. Lamination, and fabrication of the laminated circuit substrate 8 * (5) Next, as shown in Fig. 1 (4), a through hole 9 is formed by a NC drilling process at a specific position of the laminated circuit substrate 8 of -12-201221003 (φ) The diameter of the through-hole 9 is determined by the balance between the shape of the connection portion between the through-hole 9 and the mounted electronic component. Generally, the processing cost per hour is high, and the electronic component mounted after the aperture is large. The mounting height has an influence. Therefore, the diameter of the through hole 9 is set to be, for example, in the range of 100 to 300 μm. The through hole 9 is not limited to the NC drilling process, and various lasers (UV-YAG lasers) can also be used. Laser processing such as carbonic acid laser, excitation laser, etc. is formed. (6) Next, as shown in Fig. 1 (5), after the through hole 9 is subjected to a conductive treatment, the electrolytic copper plating layer is applied to laminate The outer layer of the circuit substrate 8 and the inner wall of the through hole 9 are formed The coated film 10 (for example, 8 μm thick). Thus, the through-via 1 1 〇 (7) for interlayer connection can be obtained. Next, the conductive film (copper foil) of the outer layer of the laminated circuit substrate 8 is laminated by a photo-processing method. + plating film) is processed into a specific pattern, and outer layer circuit patterns 12 Α and 12 形成 are formed on both sides of the laminated circuit substrate 8. The photoresist used in the light processing method used in the project is preferably used to have a through hole. 9 dry film resisting thickness (for example, 2 〇μηη thick). Alternatively, a liquid resist or an electric resist may be used, and the through-hole 1 1 may be protected. (8) Next, As shown in Fig. 1 (5), a solder resist layer 13 is formed in a region where insulation protection is required. An opening portion 15 is formed in the solder resist layer 13, and a pad portion 14 can be mounted on the bottom surface of the opening portion 15. (including the through hole 13 - 201221003 guide hole 1 1 ) is exposed. Then, the surface layer of the furnace layer 10 that exposes the opening 15 is subjected to a surface treatment such as a gold plating layer, and the outer shape is processed to obtain a multilayer printed wiring board having a through hole. 1 6. Figure 2 (a) shows the multilayer produced by the above method Fig. 2(b) is an end view taken along line A-A' of Fig. 2(a). Fig. 2(a) and 2(b) show the mounting welding of the multilayer printed wiring board 16. The pad portion 14 is disposed directly above the through hole 11. Thus, compared with the multilayer printed wiring board 120, the mounting density of the mounting pad portion of the multilayer printed wiring board 16 can be increased, and can be installed corresponding to the paste density. A method of mounting the surface of the electronic component on the multilayer printed wiring board 16 will be described below with reference to Figs. 3A to 3C. (1) First, a metal plate (metal mask) 20 for solder printing is prepared. The metal plate 20 has the mounting pad portions 14 of the multilayer printed wiring board 16 , 14 , . . . , and the corresponding opening portions 21 , 2 1 · _ . As shown in FIG. 3A (1), the metal portions 20 are overlapped with the mounting pads 14 , 14 , . . . of the multilayer printed wiring board 16 , respectively. The plate 20 is placed on top of the multilayer printed wiring board 16. The size of the opening portion 2 1 of the metal plate 20 is such a size as to pass through one cover 30 as will be described later. That is, the diameter of the opening portion 21 is larger than the diameter of the spherical cover 30. At the same time, in order to prevent the two lids 30 from entering the one opening portion 21, it is preferable to set the diameter of the opening portion 21 to be less than twice the diameter of the lid body 30. -14·201221003 (2) Next, as shown in FIG. 3A (2), the lid body 30 made of metal is attached to the through hole of the guide hole 11, and the body 30 is placed on the mounting pad portion 14. Each. Specifically, after depositing a plurality of covers 30, . . . on the metal plate 20, the squeegee 40 is slid on the scanning metal plate 20 to drop the one cover 30 to the opening portion 21 of the metal plate 20. The through hole is penetrated through the through hole 1 1 . The lid body 30 is fixed by air suction through the lower side of the guide hole 1 1 . The diameter of the lid body 30 is set to be 10 to 20 μm larger than the diameter of the through hole 11 by 130 μπ. The size (diameter) of the cover 30 ensures the parallelism of the electronic components and is preferably uniform. (3) Next, as shown in Fig. 3 (3), after the solder paste 50 is deposited on the master 20, the squeegee 40 is slid and solder-printed. When the solder paste 50 is buried in the inside of the opening portion 21 of the metal plate 20, the lid body 30 in the opening 21 is buried in the solder paste 50 and fixed. (4) Next, as shown in Fig. 3 (4), the metal plate 20 is removed from the printed wiring board 16. In this manner, the welding (pre-soldering layer) 5 1 , 5 1 , . . . in which the lid body 30 is embedded is formed on the mounting welds 14, 14, . (5) Next, an electronic component 60 (CSP) ' for surface mounting is prepared so that the connection portion of the electronic component 60 (61 of the electronic component 60 or the solder ball provided on the terminal 61) is placed on the soldering portion 51. The positioning of the electronic component 60 and the multilayer printed wiring board 16 is performed. Thereafter, the electronic component 60 is mounted on the multilayer printed wiring board 丨6. The cover 30, the surface, and the plug are formed in a spherical shape (about, for the gold, the multi-layered tin portion of the mouth is, for example, a terminal type, -15-201221003 (6). Next, the multi-layer printing on which the electronic component 60 is mounted The wiring board 16 is subjected to heat treatment (reflow process). Thus, as shown in Fig. 3 C (5), the solder paste of the solder portion 51 is melted to form the solder joint portion 52. The solder joint portion 52 makes the electronic component 60 is bonded to the mounting pad portion 14 of the multilayer printed wiring board 16. In this project, the cover 30 functions as a cover portion penetrating the through hole of the via hole 11, so that the molten solder does not flow into the through hole. In this case, the amount of solder constituting the solder joint portion 52 is not reduced, and the reliability of the solder joint portion 52 can be improved while maintaining the parallelism of the electronic component 60 to the multilayer printed wiring board 16. Further, the cover 30 is The sphere has a certain height at the top, and the mounting height of the electronic component 60 is stable, and the parallelism is ensured. Through the above engineering, the mounting pad portion directly above the through-via 1 1 can be obtained. 14, was installed The multilayer printed circuit board 70 of the electronic component 60. As shown in Fig. 3C (5), the multilayer printed circuit board 70 is mounted by a solder joint portion 52 provided directly above the through via hole penetrating through the via hole 11. The electronic component 60 of the multilayer printed wiring board 16 is embedded in the solder joint portion 52 to block the through hole penetrating through the via hole 11. As described above, according to the embodiment, the damage is not impaired. In the case of productivity and reliability, the surface of the electronic component can be mounted on the mounting pad portion provided directly above the through hole 11. Further, according to the present embodiment, -16-201221003 can be provided with a narrow pitch. In the electronic component, the reliability of the solder joint portion is high, and the printed circuit board having good parallelism of the electronic component. In the above description, the material of the lid body 30 is metal, but the present invention is not limited thereto, that is, the cover. The material of the body 30 may be melted in the reflow process without losing the function as a cover. Therefore, it may be an insulator such as a resin. However, from the viewpoint of solder wettability, the surface of the cover is preferably Therefore, the core body made of a resin is subjected to a plating treatment, and a resin core having a conductive film (for example, a Ni/Au plating layer) formed on the surface thereof may be used as a lid. The printing wiring for mounting electronic components may be used for relaxation. The stress of the board (printed circuit board), and the thermal expansion coefficient of the cover material is set to be the middle of the thermal expansion coefficient of the electronic component and the thermal expansion coefficient of the printed wiring board. The resin having such a thermal expansion coefficient is used as the cover 30. When the material is used, the stress caused by the difference in thermal expansion between the mounted electronic component 60 and the multilayer printed wiring board 16 can be relaxed by the elasticity of the resin. Further, the cover 30 only needs to be disposed directly above and becomes the through guide of the mounting pad portion. It can be placed on the hole, and it is not required to be placed directly above the through-hole of the mounting pad portion. As explained above, the manufacturing process can be saved by arranging the cover only at the necessary positions. Further, as described above, the shape of the lid body 30 is a spherical shape. However, the present invention is not limited thereto, that is, the shape of the lid body 30 may cover the through hole penetrating through the guide hole, for example, It is an elliptical spherical cover 30A (refer to Fig. 4 (a)), or a disc-shaped cover 30B (refer to Fig. 4 (b)) 〇-17- 201221003 Other, and the spherical body can ensure the parallel of electronic components. The shape of the degree can be composed of a disk body 30C1 that is inserted through the through hole and a column body 30C2 that is orthogonal to the disk body 30C1 (see FIG. 4(c)). In this case, the length of the columnar body 30C 2 is preferably larger than the diameter of the opening portion 15. Further, the method of mounting the electronic component of the present invention is not limited to the multilayer printed wiring board 16, and can be applied to any printed wiring board having a configuration in which a pad portion is provided directly above the via hole. The additional effects or various modifications of the present invention can be considered based on the above description, but the present invention is not limited to the wet etching described above. Various additions, modifications, and partial deletions may be made without departing from the spirit and scope of the invention as set forth in the appended claims. According to the features of the present invention, the present invention can obtain the following effects: a cover body for covering the through-hole of the through-hole is placed on the through-hole of the through-hole, and the cover is buried. Soldering part of the body (pre-solder layer). In this case, the cover body will block the through hole when the reflowing process is performed, and the molten solder does not flow into the through hole. Therefore, the amount of solder constituting the joint portion is reduced, and the reliability of the solder joint portion can be improved, and the parallelism of the electronic component to the printed wiring board can be maintained. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view showing the construction of a multilayer printed -18-201221003 wiring board having a pad portion directly above the via hole. Fig. 2(a) is a plan view showing a printed wiring board having a pad portion mounted directly above the via hole, and (b) is an end view taken along line A-A' of (a). Fig. 3A is a perspective view showing the construction of an end surface of an electronic component according to an embodiment of the present invention. Fig. 3B is a perspective view showing the construction of the surface mounting method of the electronic component according to the embodiment of the invention of Fig. 3A. Fig. 3C is a view showing an engineering end face of the surface mounting method of the electronic component according to the embodiment of the invention of Fig. 3B. Fig. 4 is an explanatory view showing an end face of a printed wiring board which is placed on a through hole through a cover body according to a modification. Fig. 5(a) is a plan view showing a printed wiring board having a mounting pad portion which is provided separately from the through hole, and Fig. 5(b) is an end view taken along line A-A' of (a). Fig. 6A is a perspective view showing the surface mounting method of the electronic component of the prior art. Fig. 6B is a view showing the end face of the surface mounting method of the electronic component of the prior art of Fig. 6A. [Description of main component symbols] ΙΑ, 1B, 101, 110: flexible insulating base material 2A ' 2B ' 3A ' 3B, 102, 103, 111, 112: copper boxes 4A, 4B, 104, 1 1 3 : circuit Substrate-19-201221003 5, 107: cover layer 5a: insulating film 5b, 1 0 9 : adhesive layer 6, 108: circuit substrate 7 with additional cover layer: 105: adhesive layer 8: laminated circuit base Material 9: through-holes 10, 1 14 : plated film 1 1 : through-holes 12A, 12B: outer layer circuit pattern 1 3, 1 1 5 : solder resist layer 14 : mounting pad portion 1 5 : opening 1 6, 1 2 0 : multilayer printed wiring board 20, 130: metal plate (metal mask) 2 1 , 1 3 1 : opening 30, 30A, 30B, 30C: cover 30C1: disk body 30C2: columnar Body 40, 1 50: Scraper 50, 1 40: Solder paste 51, 141: Soldering portion (pre-solder layer) 52, 142: Solder joint 60, 160: Electronic component -20- 201221003 6 1. 1 6 1 : terminal 70: multilayer printed circuit board 106: polyimide film 116E: mounting pad portion through guide hole 119E: opening portion 1 1 6A, 1 1 6B, 1 1 6C, 1 1 6D, 1 1 8 A, 1 1 8B, 1 1 8C, 1 1 8D : 119A ' 11 9B, 119C, 119D, -21 -