以下，一面參照圖式一面詳細地說明應用本技術之保護元件。再者，本技術並不僅限定於以下實施形態，當然可於不脫離本技術主旨之範圍內進行各種變更。又，圖式係模式性之圖，各尺寸之比例等有時與現實不同。具體尺寸等應參考以下說明進行判斷。又，當然圖式彼此間亦包含尺寸之關係或比例彼此不同之部分。 [保護元件] 如圖1、圖2所示，應用本發明之保護元件1係藉由表面安裝於電路基板2而構成電路模組3者。電路基板2例如藉由形成鋰離子蓄電池之保護電路等，並表面安裝保護元件1，而於鋰離子蓄電池之充放電路徑上組裝可熔導體13。而且，若電路模組3中流通超過保護元件1之額定值之大電流，則可熔導體13藉由自發熱(焦耳熱)而熔斷，藉此阻斷電流路徑。又，電路模組3可藉由如下方式阻斷電流路徑，即，利用設置於電路基板2等之電流控制元件於特定時序向發熱體14通電，而藉由發熱體14之發熱使可熔導體13熔斷。 再者，圖1係表示應用本發明之保護元件1之外觀立體圖，圖2係表示將保護元件1安裝於電路基板2而成之電路模組3之一部分之剖視圖，圖3係將蓋構件20省略而表示保護元件1之絕緣基板10之表面10e上之俯視圖，圖4係表示保護元件1之背面側之外觀立體圖。 如圖1～圖4所示，保護元件1具備：絕緣基板10；發熱體14，其積層於絕緣基板10，且由絕緣構件15覆蓋；第1電極11及第2電極12，其等形成於絕緣基板10之第1、第2側緣10a、10b；發熱體引出電極16，其以與發熱體14重疊之方式積層於絕緣構件15上；及可熔導體13，其兩端分別連接於第1、第2電極11、12，且其中央部連接於發熱體引出電極16。 [絕緣基板] 絕緣基板10係由例如氧化鋁、玻璃陶瓷、富鋁紅柱石、氧化鋯等具有絕緣性之構件呈大致方形狀而形成。絕緣基板10除此以外亦可使用玻璃環氧基板、酚基板等印刷配線基板中所使用之材料。 絕緣基板10形成為四邊形狀，而具有形成有第1電極11及第2電極12之相對向之第1、第2側緣10a、10b，及與該等第1、第2側緣相鄰且形成有下述第1、第2發熱體電極18、19之相對向之第3、第4側緣10c、10d。 [第1、第2電極] 第1、第2電極11、12於絕緣基板10之表面10e上，彼此相隔地配置於相對向之側緣10a、10b附近，藉此而開放，且藉由搭載下述可熔導體13而經由可熔導體13電性連接。又，第1、第2電極11、12係藉由如下方式而被阻斷，即，對保護元件1通入超過額定值之大電流，使可熔導體13藉由自發熱(焦耳熱)而熔斷，或者使發熱體14伴隨通電發熱，而將可熔導體13熔斷。 如圖2所示，第1、第2電極11、12分別經由設置於絕緣基板10之第1、第2側緣10a、10b之城堡型結構與設置於背面10f之外部連接電極11a、12a連接。保護元件1經由該等外部連接電極11a、12a與形成有外部電路之電路基板2連接，而構成該外部電路之通電路徑之一部分。 第1、第2電極11、12可使用Cu或Ag等常用電極材料而形成。又，較佳為，於第1、第2電極11、12之表面上藉由鍍覆處理等公知之手法而塗佈Ni/Au鍍覆、Ni/Pd鍍覆、Ni/Pd/Au鍍覆等被膜。藉此，保護元件1可防止第1、第2電極11、12氧化，且防止額定值伴隨導通電阻之上升而變動。又，可防止回焊安裝保護元件1時因連接可熔導體13之連接用焊料或形成可熔導體13外層之低熔點金屬熔融而熔蝕(焊料侵蝕)第1、第2電極11、12。 [發熱體] 發熱體14係具有若通電則發熱之導電性之構件，由例如W、Mo、Ru、Cu、Ag、或以其等為主成分之合金等構成。發熱體14可藉由如下方式而形成，即，將其等之合金、組成物、或化合物之粉狀體與樹脂黏合劑等混合，而製成膏狀物，然後於絕緣基板10上使用網版印刷技術對該膏狀物進行圖案形成、煅燒等處理。又，發熱體14形成為以第3、第4側緣10c、10d間為長邊之大致矩形狀，且寬度方向之一端與形成於第3側緣10c側之第1發熱體電極18連接，寬度方向之另一端與形成於第4側緣10d側之第2發熱體電極19連接。 保護元件1以覆蓋發熱體14之方式配設有絕緣構件15，且以隔著該絕緣構件15與發熱體14對向之方式形成有發熱體引出電極16。於保護元件1中，為了將發熱體14之熱高效地傳遞至可熔導體13，亦可於發熱體14與絕緣基板10之間亦積層絕緣構件15。作為絕緣構件15，例如可使用玻璃。 發熱體引出電極16之一端連接於第2發熱體電極19，並且經由第2發熱體電極19與發熱體14之一端連續。第1發熱體電極18形成於第3側緣10c側，並且沿著絕緣基板10之長邊方向形成有與發熱體14之一長邊連接之連接邊18a。同樣地，第2發熱體電極19形成於第4側緣10d側，並且沿著絕緣基板10之長邊方向形成有與發熱體14之另一長邊連接之連接邊19a。又，第1發熱體電極18經由孔部25與形成於絕緣基板10之背面10f之外部連接電極18b連接。孔部25可如圖3所示形成為形成於第3側面10c之城堡型結構，亦可形成為形成於較第3側面10c稍靠內側之通孔，或可將城堡型結構及通孔併用。又，孔部25可形成有1個或複數個。 如此，保護元件1形成為僅於第1、第2發熱體電極18、19中之一者形成有孔部25之非對稱形狀。與發熱體引出電極16連接之第2發熱體電極19相較於形成有孔部25之第1發熱體電極18，熱容量較大，且對抗熱衝擊之耐性較高。 又，應用本技術之保護元件亦可如圖5所示，於第2發熱體電極19亦形成有形成於第4側緣10d之城堡型結構、或形成於較第4側緣10d稍靠內側之通孔等孔部26。第2發熱體電極19經由孔部26與形成於絕緣基板10之背面10f之外部連接電極連接。圖5所示之保護元件27藉由於第1、第2發熱體電極18、19形成孔部25、26而形成為對稱形狀。保護元件27之形成於第2發熱體電極19之孔部26同樣地，可如圖5所示形成為城堡型結構，亦可形成為通孔，或可將城堡型結構及通孔併用。又，孔部26可形成有1個或複數個。 發熱體14藉由將保護元件1安裝於電路基板2，而經由外部連接電極18b及第1發熱體電極18與形成於電路基板2之外部電路連接。而且，發熱體14藉由於將外部電路之通電路徑阻斷之特定時序經由外部連接電極18b及第1發熱體電極18而通電、發熱，可將連接第1、第2電極11、12之可熔導體13熔斷。又，發熱體14自身之通電路徑亦會因可熔導體13熔斷而被阻斷，故而停止發熱。 [可熔導體] 可熔導體13由利用發熱體14之發熱而迅速熔斷之材料構成，例如可較佳地使用焊料、或以Sn為主成分之無鉛焊料等低熔點金屬。 又，可熔導體13亦可使用In、Pb、Ag、Cu或以其等中之任一者為主成分之合金等高熔點金屬，或者亦可為低熔點金屬與高熔點金屬之積層體。藉由含有高熔點金屬及低熔點金屬，即便回焊安裝保護元件1時，回焊溫度超過低熔點金屬之熔融溫度，從而低熔點金屬熔融，亦可抑制低熔點金屬向外部流出，從而維持可熔導體13之形狀。又，即便於熔斷時，亦能藉由低熔點金屬熔融而熔蝕(焊料侵蝕)高熔點金屬，藉此以高熔點金屬之熔點以下之溫度將其迅速熔斷。 再者，可熔導體13係藉由焊料等而連接於發熱體引出電極16及第1、第2電極11、12。可熔導體13可藉由回焊焊接而容易地連接。 又，可熔導體13為了防止氧化、提高潤濕性等，較佳為塗佈有助熔劑17。 [蓋構件] 又，保護元件1為了保護內部，而於絕緣基板10之表面10e上設置有蓋構件20。蓋構件20係對應於絕緣基板10之形狀而形成為大致矩形狀。又，如圖1所示，蓋構件20具有：側面21，其連接於設置有可熔導體13之絕緣基板10之表面10e上；及頂面22，其覆蓋絕緣基板10之表面10e上；且於絕緣基板10之表面10e上，具有充分足夠可熔導體13於熔融時呈球狀膨脹且熔融導體於發熱體引出電極16或第1、第2電極11、12上凝聚之內部空間。 於蓋構件20中，側面21藉由接著劑或熔接等連接於絕緣基板10之表面10e上。作為連接蓋構件20之接著劑，可較佳地使用連接可靠性優異之熱硬化性之接著劑。 [製造步驟] 繼而，對保護元件1之製造步驟進行說明。首先，於絕緣基板10之表面10e形成第1、第2電極11、12、發熱體14、第1、第2發熱體電極18、19、絕緣構件15及發熱體引出電極16。又，於絕緣基板10之背面10f形成外部連接電極11a、12a、18b，並且經由城堡型結構或孔部25將其等與第1、第2電極11、12及第1發熱體電極18連接。然後，將可熔導體13隔著發熱體引出電極16橫跨於第1、第2電極11、12間而搭載。再者，亦可對可熔導體13與第1、第2電極11、12及發熱體引出電極16之間供給連接焊料。 其次，將蓋構件20連接於絕緣基板10之表面10e上。蓋構件20之連接較佳為藉由將連接強度優異之熱硬化性之接著劑供給至側面21之下部而進行。 繼而，將絕緣基板10之表面10e上搭載有蓋構件20之構造體加熱處理，而將可熔導體13經由連接用焊料與第1、第2電極11、12及發熱體引出電極16連接，又，將熱硬化性之接著劑硬化而將蓋構件20連接於絕緣基板10之表面10e上，藉此形成保護元件1。保護元件1藉由回焊等安裝於形成有電源電路等之電路基板2，藉此形成電路模組3。 [可熔導體之中心與發熱體之發熱中心之一致] 此時，保護元件1較佳為以可熔導體13之中心與發熱體14之發熱中心重疊之方式搭載可熔導體13。於形成為矩形板狀體之可熔導體13中，可熔導體13之中心係指可熔導體13之重心位置。發熱體14之發熱中心係指發熱初期溫度最高之位置，於形成為矩形狀之發熱體14中，其係指發熱體14之重心位置。 藉由使可熔導體13之中心與發熱體14之發熱中心重疊而搭載，可將發熱體14之熱高效地傳遞至可熔導體13，且於發熱後可迅速將可熔導體13熔斷。又，藉由將發熱體14之熱高效地傳遞至可熔導體13，可防止絕緣基板10或發熱體14自身過熱，從而可抑制龜裂之發生。 [各部之配置] 此處，發熱體14之發熱量係對應於發熱體14之大小而變大。又，設置於第1發熱體電極18之孔部25與發熱體14之距離相對較近，容易受到伴隨發熱體14之發熱而產生之熱衝擊之影響。因此，若使用應保護元件1之高容量化要求而大型化之可熔導體13，並且欲藉由發熱體14獲得使大型可熔導體13迅速熔融之發熱量，則存在因熱衝擊而朝向孔部25地於絕緣基板或發熱體14發生龜裂之虞。於發熱體14中，發生龜裂之部位之發熱停止，故而無法獲得所期望之發熱量，從而亦存在可熔導體13之熔斷時間延長之虞。 因此，保護元件1得當地配置發熱體14或孔部25等構成保護元件1之各構成部位，藉此可防止因發熱體14通電發熱時之熱衝擊而朝向孔部25地發生龜裂。 具體而言，如圖6所示，保護元件1係發熱體14之發熱中心C1自絕緣基板10之第3側緣10c至第4側緣10d之距離的中間位置C2向設置有上述第1、第2發熱體電極18、19中熱容量較大之發熱體電極之側緣側偏倚而形成。如上所述，保護元件1係於第2發熱體電極19形成有發熱體引出電極16並且未形成孔部25，故而該第2發熱體電極19相較於形成有孔部25之第1發熱體電極18，熱容量較大。因此，保護元件1係發熱體14之發熱中心C1向設置有第2發熱體電極19之第4側緣10d側偏倚而形成。 藉此，於保護元件1中，發熱體14之發熱對孔部25與發熱體14之第3側緣10c側之端部間之區域的熱衝擊變弱，從而可防止龜裂之發生。再者，於圖5所示之在第2發熱體電極19亦形成有孔部26之對稱型保護元件27中，使發熱體14之發熱中心向設置有第1、第2發熱體電極18、19中熱容量較大之發熱體電極之側緣側偏倚而形成。 又，保護元件1亦能以如下方式形成，即，按以下所述定義圖7所示之保護元件1之俯視圖中的各部之尺寸，使之滿足以下所說明之第1～第7形態所示之條件。 A：絕緣基板10之第3側緣10c與發熱體14之第3側緣10c側之端部的最短距離 B：發熱體14之第3側緣10c側之端部與設置於第1發熱體電極18之孔部25之外緣的最短距離 C：絕緣基板10之第4側緣10d與發熱體14之第4側緣10d側之端部的最短距離 D：通過絕緣基板10之第3、第4側緣10c、10d間之中心部且平行於第3、第4側緣10c、10d的中心線與發熱體14之第3側緣10c側之端部的距離 E：通過絕緣基板10之第3、第4側緣10c、10d間之中心部且平行於第3、第4側緣10c、10d之中心線與發熱體14之第4側緣10d側之端部的距離 F：絕緣基板10之第3、第4側緣10c、10d間之距離 G：形成為大致矩形狀之發熱體14之寬度 H：與絕緣基板10之第3、第4側緣10c、10d相鄰之第1、第2側緣10a、10b間之距離 此處，若對B進行補充，則於存在複數個孔部25之情形時，B係指發熱體14之第3側緣10c側之端部與位於最靠發熱體14側之孔部25之外緣的最短距離。圖8係表示具有形成於較第3側緣10c稍靠內側之通孔作為設置於第1發熱體電極18之孔部25的保護元件1之俯視圖。於圖8所示之保護元件1中，孔部25之外緣成為該通孔之外緣。 又，圖9係表示具有設置於第3側緣10c之城堡型結構、及形成於較第3側緣10c稍靠內側之通孔作為設置於第1發熱體電極18之孔部25的保護元件1之俯視圖。於圖9所示之保護元件1中，孔部25之外緣成為位於最靠發熱體14側之通孔之外緣。 又，於在第1發熱體電極18設置有孔部25並且在第2發熱體電極19設置有孔部26之對稱型保護元件27中，針對第1、第2發熱體電極18、19及第3、第4側緣10c、10d，將形成有熱容量較小之發熱體電極之孔部之外緣與形成有該發熱體電極之側緣的距離設為B，將形成有熱容量較大之發熱體電極之孔部之外緣與形成有該發熱體電極之側緣的距離設為C。 [第1形態：B/(D＋E)] 保護元件1較佳為將B/(D＋E)設定為0.20以上。即，保護元件1較佳為，發熱體14之第3側緣10c側之端部與設置於第1發熱體電極18之孔部25之外緣之最短距離(B)相對於發熱體14之長度(D＋E)的比率為0.20以上。 發熱體14之發熱量對應於發熱體14之長度(D＋E)而變大，又，發熱體14與孔部25之距離越長則對抗龜裂之耐性越大。而且，藉由將發熱體14至孔部25之距離(B)相對於發熱體14之長度(D＋E)的比率設定為0.20以上，可使對抗發熱體14之發熱量之耐性提高，從而可防止朝向孔部25之龜裂之發生。 另一方面，於發熱體14至孔部25之距離(B)相對於發熱體14之長度(D＋E)的比率未達0.20之情形時，較之發熱體14之長度(D＋E)而言發熱體14與孔部25之距離甚為短小，對抗熱衝擊之耐性不足，而存在發生龜裂之虞。 [第2形態：B/G] 又，保護元件1較佳為將B/G設定為1.0以上。即，保護元件1較佳為，發熱體14之第3側緣10c側之端部與孔部25之外緣之最短距離(B)相對於形成為大致矩形狀之發熱體14之寬度(G)的比率為1.0以上。 發熱體14之發熱量亦對應於發熱體14之寬度(G)而變大，寬度越寬則朝向孔部25之傳熱通路亦越寬，故而越容易被熱衝擊之影響所波及。又，發熱體14與孔部25之距離越長則對抗龜裂之耐性越大。因此，藉由將發熱體14至孔部25之距離(B)相對於發熱體之寬度(G)的比率設定為1.0以上，可具備對抗發熱體14之發熱量之耐性，從而可防止朝向孔部25之龜裂之發生。 另一方面，於發熱體14至孔部25之距離(B)相對於發熱體之寬度(G)的比率未達1.0之情形時，較之發熱體14之寬度(G)而言發熱體14與孔部25之距離甚為短小，對抗熱衝擊之耐性不足，而存在發生龜裂之虞。 [第3形態：B/(G/(D＋E))] 又，保護元件1較佳為將B/(G/(D＋E))設定為6.0以上。即，保護元件1較佳為，發熱體14之第3側緣10c側之端部與孔部25之外緣之最短距離(B)相對於發熱體14之寬度(G)與長度(D＋E)之縱橫比(G/(D＋E))的比率為6.0以上。 於特定尺寸之絕緣基板10內，若使發熱體14之第3側緣10c側之端部與孔部25之外緣的最短距離(B)較大，則相對性地遍及第3、第4側緣10c、10d間而設置之發熱體14之長度(D＋E)之距離變短，發熱量變小。又，若發熱體14之寬度(G)變小則發熱量變小。 因此，於特定尺寸之絕緣基板中，藉由規定發熱體14至孔部25之距離(B)相對於發熱體14之寬度(G)與長度(D＋E)之縱橫比(G/(D＋E))的比率，可具備對抗發熱體14之發熱量之耐性。具體而言，藉由將發熱體14至孔部25之距離B相對於發熱體14之寬度(G)與長度(D＋E)之縱橫比(G/(D＋E))的比率設定為6.0以上，可具備對抗發熱體14之發熱量之耐性，從而可防止朝向孔部25之龜裂之發生。 另一方面，於發熱體14至孔部25之距離B相對於發熱體14之寬度(G)與長度(D＋E)之縱橫比(G/(D＋E))的比率未達6.0之情形時，較之發熱體14之長度(D＋E)或發熱體14之寬度(G)而言發熱體14與孔部25之距離甚為短小，對抗熱衝擊之耐性不足，而存在發生龜裂之虞。 [第4形態：B/(B＋D＋E＋C)] 又，保護元件1較佳為將B/(B＋D＋E＋C)設定為0.15以上。即，較佳為，發熱體14之第3側緣10c側之端部與孔部25之外緣之最短距離(B)相對於孔部25之外緣至第4側緣10d之距離(B＋D＋E＋C)的比率為0.15以上。 於絕緣基板10中，由於在第3側緣10c側設置有孔部25，故而絕緣基板10之發熱體14至孔部25此片區域對抗熱衝擊之耐性成為問題，因此絕緣基板10之除第3側緣10c至孔部25此片區域以外之區域、即孔部25之外緣至第4側緣10d之距離(B＋D＋E＋C)可謂之為承受發熱體14之熱衝擊之實質性的絕緣基板10之長度。而且，該承受發熱體14之熱衝擊之孔部25之外緣至第4側緣10d之距離(B＋D＋E＋C)中，發熱體14之第3側緣10c側之端部與孔部25之外緣之最短距離(B)的比率越大，則越可具備對抗發熱體14之發熱量之耐性。具體而言，藉由將B/(B＋D＋E＋C)設定為0.15以上，可具備對抗發熱體14之發熱量之耐性，從而可防止朝向孔部25之龜裂之發生。 另一方面，於孔部25之外緣至第4側緣10d之距離(B＋D＋E＋C)中發熱體14之第3側緣10c側之端部與孔部25之外緣之最短距離(B)的比率未達0.15之情形時，實質性的絕緣基板10之長度(B＋D＋E＋C)中發熱體14與孔部25之距離較短，對抗熱衝擊之耐性不足，而存在發生龜裂之虞。 [第5形態：B/C] 又，保護元件1較佳為將B/C設定為0.9以上。即，於特定尺寸之絕緣基板10中，較佳為，發熱體14之第3側緣10c側之端部與孔部25之外緣之最短距離(B)相對於絕緣基板10之第4側緣10d與發熱體14之第4側緣10d側之端部之最短距離(C)的比率為0.9以上。 於絕緣基板10之表面10e之第3、第4側緣10c、10d間所占的發熱體14之長度(D＋E)固定時，作為發熱體14之兩端部與孔部25之外緣及第4側緣10d之距離的比率，使發熱體14之第3側緣10c側之端部與孔部25之外緣的最短距離(B)較大，具體而言設定為0.9以上，藉此可使發熱體14向第4側緣10d側偏倚，使發熱體14至容易發生龜裂之孔部25此片區域對抗熱衝擊之耐性提高，從而可防止朝向孔部25之龜裂之發生。 另一方面，在絕緣基板10之表面10e中，於發熱體14之第3側緣10c側之端部與孔部25之外緣之最短距離(B)相對於絕緣基板10之第4側緣10d與發熱體14之第4側緣10d側之端部之最短距離(C)的比率未達0.9之情形時，發熱體14與孔部25之距離較短，對抗熱衝擊之耐性不足，而存在發生龜裂之虞。 [第6形態：B/(F－(E＋C))] 又，保護元件1較佳為將B/(F－(E＋C))設定為0.30以上。即，較佳為，發熱體14之第3側緣10c側之端部與孔部25之外緣之最短距離(B)相對於絕緣基板10之第3側緣10c至絕緣基板10之第3、第4側緣10c、10d間之中心位置之距離(F－(E＋C))的比率為0.30以上。 距第3側緣10c之距離(F－(E＋C))表示絕緣基板10之第3、第4側緣10c、10d間之中心位置，距離(B)表示孔部25之外緣至發熱體14之端部之距離。因此，B/(F－(E＋C))係規定絕緣基板10之中心位置與發熱體14之第3側緣10c側之端部的位置關係。 而且，藉由具有使發熱體14之第3側緣10c側之端部與孔部25之外緣之最短距離(B)相對於絕緣基板10之第3側緣10c至絕緣基板10之第3、第4側緣10c、10d間之中心位置之距離(F－(E＋C))的比率為0.30以上之位置關係，可於絕緣基板10之中心位置至第3側緣10c側區域中容易發生龜裂之孔部25此片區域確保具備對抗發熱體14之熱衝擊之耐性之長度，從而可防止朝向孔部25之龜裂之發生。 另一方面，於發熱體14之第3側緣10c側之端部與孔部25之外緣之最短距離(B)相對於絕緣基板10之第3側緣10c至絕緣基板10之第3、第4側緣10c、10d間之中心位置之距離(F－(E＋C))的比率未達0.30之情形時，在絕緣基板10之中心位置至第3側緣10c側之區域中發熱體14與孔部25之距離較短，對抗熱衝擊之耐性不足，而存在發生龜裂之虞。 再者，絕緣基板10之第3側緣10c至絕緣基板10之第3、第4側緣10c、10d間之中心位置的距離除了(F－(E＋C))以外，亦可規定為(A+D)或(F/2)。 [第7形態：｛B+(D＋E)/2｝/｛(B+C+D+E)/2｝] 又，保護元件1較佳為，孔部25之外緣至發熱體14之中心之距離｛B+(D＋E)/2｝相對於孔部25之外緣至絕緣基板10之第4側緣10d的一半長度之距離｛(B+C+D+E)/2｝的比率｛B+(D＋E)/2｝/｛(B+C+D+E)/2｝為0.99以上。 所謂孔部25之外緣至絕緣基板10之第4側緣10d的一半長度之距離｛(B+C+D+E)/2｝表示上述實質性的絕緣基板10之中心，藉由求出其與孔部25之外緣至發熱體14之中心之距離｛B+(D＋E)/2｝的比率，而規定發熱中心於該實質性的絕緣基板10內之位置。而且，藉由以｛B+(D＋E)/2｝/｛(B+C+D+E)/2｝成為0.99以上之方式形成發熱體14，發熱體14之發熱中心會與實質性的絕緣基板10之中心大致一致或向第4側緣10d側偏倚。因此，可於發熱體14之發熱中心至孔部25此片區域確保具備對抗發熱體14之熱衝擊之耐性之長度，從而可防止朝向孔部25之龜裂之發生。 另一方面，於孔部25之外緣至發熱體14之中心之距離｛B+(D＋E)/2｝相對於孔部25之外緣至絕緣基板10之第4側緣10d的一半長度之距離｛(B+C+D+E)/2｝的比率未達0.99之情形時，發熱體14之發熱中心自實質性的絕緣基板之中心向第3側緣10c側偏倚而設置，無法於發熱體14至孔部25此片區域確保具備對抗發熱體14之熱衝擊之耐性之長度，而存在發生朝向孔部25之龜裂之虞。 [電路基板] 繼而，對供安裝保護元件1之電路基板2進行說明。電路基板2例如可使用玻璃環氧基板、玻璃基板、或陶瓷基板等剛性基板、或者軟性基板等公知之絕緣基板。又，電路基板2如圖2所示，具有藉由回焊等表面安裝保護元件1之安裝部，且於安裝部內設置有分別與設置於保護元件1之絕緣基板10之背面10f之外部連接電極11a、12a、18b連接的連接電極。再者，電路基板2安裝有使保護元件1之發熱體14通電之FET等元件。 [電路模組之使用方法] 其次，對保護元件1及將保護元件1表面安裝於電路基板2而成之電路模組3之使用方法進行說明。如圖10所示，電路模組3例如可用作鋰離子蓄電池之電池組內之電路。 例如，保護元件1係組裝至具有電池堆55之電池組50而使用，該電池堆55包含共計4個鋰離子蓄電池之電池單元51～54。 電池組50具備：電池堆55；充放電控制電路60，其控制電池堆55之充放電；應用本發明之保護元件1，其於電池堆55異常時將充電阻斷；檢測電路56，其檢測各電池單元51～54之電壓；及電流控制元件57，其根據檢測電路56之檢測結果控制保護元件1之動作。 電池堆55係將需進行保護控制以免出現過充電及過放電狀態之電池單元51～54串聯連接而成者，經由電池組50之正極端子50a、負極端子50b能夠裝卸地連接於充電裝置65，而被施加來自充電裝置65之充電電壓。將藉由充電裝置65而充電後之電池組50之正極端子50a、負極端子50b連接於要利用電池來動作之電子設備，藉此可使該電子設備動作。 充放電控制電路60具備：2個電流控制元件61、62，其等串聯連接於自電池堆55流向充電裝置65之電流路徑；及控制部63，其控制該等電流控制元件61、62之動作。電流控制元件61、62例如包含電場效應電晶體(以下，稱為FET)，藉由利用控制部63控制閘極電壓，而控制向電池堆55之電流路徑之充電方向及/或放電方向之導通及阻斷。控制部63自充電裝置65接受電力供給而動作，根據由檢測電路56檢測出之檢測結果，以於電池堆55為過放電或過充電時將電流路徑阻斷之方式，控制電流控制元件61、62之動作。 保護元件1例如連接於電池堆55與充放電控制電路60之間之充放電電流路徑上，且其動作由電流控制元件57控制。 檢測電路56與各電池單元51～54連接，檢測各電池單元51～54之電壓值，並將各電壓值供給至充放電控制電路60之控制部63。又，檢測電路56於任一個電池單元51～54變成過充電電壓或過放電電壓時輸出控制電流控制元件57之控制信號。 電流控制元件57例如包含FET，根據自檢測電路56輸出之檢測信號，於電池單元51～54之電壓值變成特定之超過過放電或過充電狀態之電壓時，使保護元件1動作，而以無論電流控制元件61、62之開關動作如何均將電池堆55之充放電電流路徑阻斷之方式進行控制。 於包含如上構成之電池組50中，對保護元件1之構成具體地進行說明。 首先，應用本發明之保護元件1具有如圖11所示之電路構成。即，保護元件1係包含如下構件之電路構成：可熔導體13，其經由發熱體引出電極16而串聯連接；及發熱體14，其經由可熔導體13之連接點而通電並發熱，藉此將可熔導體13熔融。又，於保護元件1中，例如，可熔導體13串聯連接於充放電電流路徑上，發熱體14與電流控制元件57連接。保護元件1之第1電極11經由外部連接電極11a與電池堆55之開放端連接，第2電極12經由外部連接電極12a與電池組50之正極端子50a側之開放端連接。又，發熱體14藉由經由發熱體引出電極16與可熔導體13連接而與電池組50之充放電電流路徑連接，又，經由第1發熱體電極18及外部連接電極18b與電流控制元件57連接。 若保護元件1之發熱體14通電、發熱，則可熔導體13熔融，藉由其潤濕性，此種電池組50會被拖引至發熱體引出電極16上。其結果，保護元件1能藉由可熔導體13熔斷而確實地阻斷電流路徑。又，朝向發熱體14之供電路徑亦會因可熔導體13熔斷而被阻斷，故而發熱體14之發熱亦停止。 又，電池組50於充放電路徑上流通有超過保護元件1之額定值之預期以外之大電流的情形時，能藉由使可熔導體13利用自發熱(焦耳熱)熔斷而阻斷電流路徑。 如上所述，保護元件1得當地配置發熱體14或孔部25等構成保護元件1之各構成部位，故而可防止因發熱體14通電發熱時之熱衝擊而朝向孔部25地發生龜裂，又，可將發熱體14之發熱高效地傳遞至可熔導體13。因此，保護元件1可於發熱體14通電發熱時獲得所期望之發熱量，從而穩定地維持可熔導體13之熔斷特性。 再者，應用本技術之保護元件1並不限定於用在鋰離子蓄電池之電池組中之情形，當然能夠應用於避免IC(integrated circuit，積體電路)之異常過熱等需要利用電氣信號而阻斷電流路徑之各種用途。 [實施例] 其次，對本技術之實施例進行說明。於本實施例中，形成改變上述保護元件1之A～H之各部尺寸及配置的實施例1～3及比較例1～5之樣品，驗證發熱體(電力：33 W)發熱時龜裂發生之有無。於龜裂發生於絕緣基板或發熱體中之任一者之情形時，記為「有」。 各樣品之保護元件係以如下方式形成之非對稱型，即，使用矩形狀之陶瓷基板(長度F：9.5 mm，寬度H：5.0 mm)作為絕緣基板10，於絕緣基板10之長邊方向兩側之第3、第4側緣10c、10d形成第1、第2發熱體電極18、19，並且僅在形成於第3側緣10c側之第1發熱體電極18形成城堡型結構作為孔部25，將發熱體引出電極16連接於形成在第4側緣10d側之第2發熱體電極19。 將各實施例及比較例之樣品之尺寸示於表1，將上述第1～第7形態中之數值、及龜裂發生之有無示於表2。 [表1]
[表2]
[第1形態：關於B/(D＋E)] 於實施例1～3中，發熱體14之第3側緣10c側之端部與設置於第1發熱體電極18之孔部25之外緣之最短距離B相對於發熱體14之長度(D＋E)的比率(B/(D＋E))為0.20以上，對抗發熱體14之發熱量之耐性提高，未發生朝向孔部25之龜裂。 於比較例1～5中，(B/(D＋E))未達0.20，較之發熱體14之長度(D＋E)而言發熱體14與孔部25之距離甚為短小，對抗熱衝擊之耐性不足，從而發生了龜裂。 [第2形態：關於B/G] 於實施例1～3中，發熱體14之第3側緣10c側之端部與孔部25之外緣之最短距離(B)相對於形成為大致矩形狀之發熱體14之寬度(G)的比率為1.0以上，具備對抗發熱體14之發熱量之耐性，故而未發生朝向孔部25之龜裂。 於比較例1～5中，(B/G)未達1.0，較之發熱體14之寬度(G)而言發熱體14與孔部25之距離甚為短小，對抗熱衝擊之耐性不足，從而發生了龜裂。 [第3形態：關於B/(G/(D＋E))] 於實施例1～3中，發熱體14之第3側緣10c側之端部與孔部25之外緣之最短距離(B)相對於發熱體14之寬度(G)與長度(D＋E)之縱橫比(G/(D＋E))的比率為6.0，於特定尺寸(9.5×5.0 mm)之絕緣基板10內，可相對於發熱體14之寬度(G)與長度(D＋E)之縱橫比(G/(D＋E))確保僅具備對抗發熱體14之發熱量之耐性的發熱體14至孔部25之距離(B)，從而可防止朝向孔部25之龜裂之發生。 另一方面，於比較例1～5中，B/(G/(D＋E))未達6.0，較之發熱體14之長度(D＋E)或發熱體14之寬度(G)而言發熱體14與孔部25之距離甚為短小，對抗熱衝擊之耐性不足，從而發生了龜裂。 [第4形態：關於B/(B＋D＋E＋C)] 於實施例1～3中，發熱體14之第3側緣10c側之端部與孔部25之外緣之最短距離(B)相對於孔部25之外緣至第4側緣之距離(B＋D＋E＋C)的比率為0.15以上，故而發熱體14之第3側緣10c側之端部與孔部25之外緣之最短距離(B)相對於承受發熱體14之熱衝擊之實質性的絕緣基板10之長度的比率較大，具備對抗發熱體14之發熱量之耐性，從而未發生朝向孔部25之龜裂。 另一方面，於比較例1～5中，B/(B＋D＋E＋C)未達0.15，實質性的絕緣基板10之長度(B＋D＋E＋C)中發熱體14之第3側緣10c側之端部與孔部25之外緣之最短距離(B)較短，對抗熱衝擊之耐性不足，從而發生了龜裂。 [第5形態：關於B/C] 於實施例1～3中，在特定尺寸(9.5×5.0 mm)之絕緣基板10內，發熱體14之第3側緣10c側之端部與孔部25之外緣之最短距離(B)相對於第4側緣10d與發熱體14之第4側緣10d側之端部之最短距離(C)的比率為0.9以上，發熱體14向第4側緣10d側偏倚而形成，藉此發熱體14至容易發生龜裂之孔部25此片區域對抗熱衝擊之耐性提高，故而未發生朝向孔部25之龜裂。 另一方面，於比較例1～5中，B/C未達0.9，發熱體14之第3側緣10c側之端部與孔部25之外緣之最短距離(B)較短，對抗熱衝擊之耐性不足，從而發生了龜裂。 [第6形態：關於B/(F－(E＋C))] 於實施例1～3中，發熱體14之第3側緣10c側之端部與孔部25之外緣之最短距離(B)相對於絕緣基板10之第3側緣10c至絕緣基板10之第3、第4側緣10c、10d間之中心位置之距離(F－(E＋C))的比率為0.30以上，於絕緣基板10之中心位置至第3側緣10c側區域中容易發生龜裂之孔部25此片區域確保了具備對抗發熱體14之熱衝擊之耐性之長度，故而未發生朝向孔部25之龜裂。 另一方面，於比較例1～5中，B/(F－(E＋C))未達0.30，在絕緣基板10之中心位置至第3側緣10c側之區域中發熱體14之第3側緣10c側之端部與孔部25之外緣之最短距離(B)較短，對抗熱衝擊之耐性不足，從而發生了龜裂。 [第7形態：關於｛B+(D＋E)/2｝/｛(B+C+D+E)/2｝] 於實施例1～3中，孔部25之外緣至發熱體14之中心之距離｛B+(D＋E)/2｝相對於孔部25之外緣至絕緣基板10之第4側緣10d的一半長度之距離｛(B+C+D+E)/2｝的比率｛B+(D＋E)/2｝/｛(B+C+D+E)/2｝為0.99以上，發熱體14之發熱中心與實質性的絕緣基板10之中心大致一致或向第4側緣10d側偏倚，故而可於發熱體14之發熱中心至孔部25此片區域確保具備對抗發熱體14之熱衝擊之耐性之長度，未發生朝向孔部25之龜裂。 另一方面，於比較例1～5中，｛B+(D＋E)/2｝/｛(B+C+D+E)/2｝未達0.99，發熱體14之發熱中心自實質性的絕緣基板之中心向第3側緣10c側偏倚而設置，無法於發熱體14至孔部25此片區域確保具備對抗發熱體14之熱衝擊之耐性之長度，從而發生了朝向孔部25之龜裂。Hereinafter, the protective element to which the present technology is applied will be described in detail with reference to the drawings. In addition, the present invention is not limited to the embodiments described below, and various modifications can be made without departing from the spirit and scope of the invention. Moreover, the schema is a schematic diagram, and the ratio of each dimension may be different from reality. The specific dimensions and the like should be judged by referring to the following instructions. Moreover, of course, the drawings also include portions in which the relationship or the ratios are different from each other. [Protection Element] As shown in FIGS. 1 and 2, the protection element 1 to which the present invention is applied is formed by being surface-mounted on the circuit board 2 to constitute the circuit module 3. The circuit board 2 is assembled with a protective circuit of a lithium ion battery, for example, and the protective element 1 is surface-mounted, and the fusible conductor 13 is assembled on the charge and discharge path of the lithium ion battery. Further, when a large current exceeding the rated value of the protective element 1 flows in the circuit module 3, the soluble conductor 13 is blown by self-heating (Joule heat), thereby blocking the current path. Further, the circuit module 3 can block the current path by energizing the heat generating body 14 at a specific timing by the current control element provided on the circuit board 2 or the like, and the fusible conductor can be made by the heat generated by the heat generating body 14. 13 blown. 1 is a perspective view showing the appearance of a protective element 1 to which the present invention is applied, and FIG. 2 is a cross-sectional view showing a part of the circuit module 3 in which the protective element 1 is mounted on the circuit board 2, and FIG. 3 is a cover member 20; The top view of the surface 10e of the insulating substrate 10 of the protective element 1 is omitted, and FIG. 4 is an external perspective view showing the back side of the protective element 1. As shown in FIGS. 1 to 4, the protective element 1 includes an insulating substrate 10, a heat generating body 14 laminated on the insulating substrate 10, and covered with an insulating member 15, and the first electrode 11 and the second electrode 12 are formed in the same manner. The first and second side edges 10a and 10b of the insulating substrate 10; the heating element extraction electrode 16 laminated on the insulating member 15 so as to overlap the heating element 14, and the soluble conductor 13 having its two ends connected to the first 1. The second electrodes 11 and 12 are connected to the heating element extraction electrode 16 at the center. [Insulating Substrate] The insulating substrate 10 is formed of a member having insulating properties such as alumina, glass ceramic, mullite, or zirconia in a substantially square shape. In addition to the insulating substrate 10, a material used for a printed wiring board such as a glass epoxy substrate or a phenol substrate can be used. The insulating substrate 10 is formed in a quadrangular shape, and has first and second side edges 10a and 10b on which the first electrode 11 and the second electrode 12 are formed, and adjacent to the first and second side edges. The third and fourth side edges 10c and 10d of the first and second heat generating body electrodes 18 and 19 are formed to face each other. [First and second electrodes] The first and second electrodes 11 and 12 are disposed on the front surface 10e of the insulating substrate 10 so as to be spaced apart from each other in the vicinity of the side edges 10a and 10b, thereby being mounted thereon. The fusible conductor 13 described below is electrically connected via the fusible conductor 13. Further, the first and second electrodes 11 and 12 are blocked by applying a large current exceeding the rated value to the protective element 1 to cause the fusible conductor 13 to self-heat (Joule heat). On the other hand, the fuse element 14 is blown, or the heat generating body 14 is heated by electric conduction, and the fusible conductor 13 is melted. As shown in FIG. 2, the first and second electrodes 11 and 12 are connected to the external connection electrodes 11a and 12a provided on the back surface 10f via a castle-type structure provided on the first and second side edges 10a and 10b of the insulating substrate 10, respectively. . The protective element 1 is connected to the circuit board 2 on which the external circuit is formed via the external connection electrodes 11a and 12a, and constitutes a part of the energization path of the external circuit. The first and second electrodes 11 and 12 can be formed using a common electrode material such as Cu or Ag. Further, it is preferable to apply Ni/Au plating, Ni/Pd plating, Ni/Pd/Au plating to the surfaces of the first and second electrodes 11 and 12 by a known method such as a plating treatment. Wait for the film. Thereby, the protective element 1 can prevent oxidation of the first and second electrodes 11 and 12 and prevent the rated value from fluctuating with an increase in the on-resistance. Further, it is possible to prevent the first and second electrodes 11 and 12 from being eroded (solder erosion) by the solder for connection of the connection of the fusible conductor 13 or the low-melting-point metal forming the outer layer of the fusible conductor 13 when the protective element 1 is reflow-welded. [Heating element] The heating element 14 is a member having electrical conductivity that generates heat when it is energized, and is made of, for example, W, Mo, Ru, Cu, Ag, or an alloy containing the main component thereof. The heating element 14 can be formed by mixing an alloy, a composition, or a powder of a compound with a resin binder or the like to form a paste, and then using a mesh on the insulating substrate 10. The plate printing technique performs processing such as patterning, calcination, and the like on the paste. In addition, the heating element 14 is formed in a substantially rectangular shape having a long side between the third and fourth side edges 10c and 10d, and one end in the width direction is connected to the first heating element electrode 18 formed on the third side edge 10c side. The other end in the width direction is connected to the second heat generating body electrode 19 formed on the fourth side edge 10d side. The protective element 1 is provided with an insulating member 15 so as to cover the heating element 14, and the heating element extraction electrode 16 is formed to face the heating element 14 with the insulating member 15 interposed therebetween. In the protective element 1, in order to efficiently transfer the heat of the heat generating body 14 to the soluble conductor 13, the insulating member 15 may be laminated between the heat generating body 14 and the insulating substrate 10. As the insulating member 15, for example, glass can be used. One end of the heating element extraction electrode 16 is connected to the second heating element electrode 19, and is continuous with one end of the heating element 14 via the second heating element electrode 19. The first heating element electrode 18 is formed on the third side edge 10c side, and a connecting side 18a that is connected to one long side of the heating element 14 is formed along the longitudinal direction of the insulating substrate 10. Similarly, the second heat generating body electrode 19 is formed on the fourth side edge 10d side, and a connecting side 19a that is connected to the other long side of the heat generating body 14 is formed along the longitudinal direction of the insulating substrate 10. Further, the first heating element electrode 18 is connected to the external connection electrode 18b formed on the back surface 10f of the insulating substrate 10 via the hole portion 25. The hole portion 25 may be formed in a castle-type structure formed on the third side surface 10c as shown in FIG. 3, or may be formed in a through hole slightly inside the third side surface 10c, or may be used in combination with a castle type structure and a through hole. . Further, the hole portion 25 may be formed in one or a plurality of. In this manner, the protective element 1 is formed such that only one of the first and second heat generating body electrodes 18 and 19 has an asymmetrical shape in which the hole portion 25 is formed. The second heating element electrode 19 connected to the heating element extraction electrode 16 has a larger heat capacity than the first heating element electrode 18 in which the hole portion 25 is formed, and has high resistance against thermal shock. Further, as shown in FIG. 5, the protective element to which the present technique is applied may be formed in the castle-type structure formed on the fourth side edge 10d or on the inner side of the fourth side edge 10d in the second heating element electrode 19. The hole portion 26 such as a through hole. The second heating element electrode 19 is connected to an external connection electrode formed on the back surface 10f of the insulating substrate 10 via the hole portion 26. The protective element 27 shown in FIG. 5 is formed in a symmetrical shape by forming the hole portions 25 and 26 in the first and second heat generating body electrodes 18 and 19. Similarly, the hole portion 26 of the protective element 27 formed on the second heat generating body electrode 19 may be formed in a castle-like structure as shown in FIG. 5, or may be formed as a through hole, or may be used in combination with a castellation structure and a through hole. Further, the hole portion 26 may be formed in one or a plurality of. The heating element 14 is connected to the external circuit formed on the circuit board 2 via the external connection electrode 18b and the first heating element electrode 18 by attaching the protective element 1 to the circuit board 2. In addition, the heating element 14 is energized and generates heat via the external connection electrode 18b and the first heating element electrode 18 at a specific timing for blocking the energization path of the external circuit, and the first and second electrodes 11 and 12 can be melted. The conductor 13 is blown. Further, since the energizing path of the heating element 14 itself is blocked by the meltable conductor 13, the heat generation is stopped. [Fuse Conductor] The fusible conductor 13 is made of a material that is rapidly blown by heat generated by the heat generating body 14. For example, solder or a low melting point metal such as lead-free solder containing Sn as a main component can be preferably used. Further, the fusible conductor 13 may be a high melting point metal such as In, Pb, Ag, Cu, or an alloy containing any of them, or a laminate of a low melting point metal and a high melting point metal. By including a high melting point metal and a low melting point metal, even when the protective element 1 is reflowed, the reflow temperature exceeds the melting temperature of the low melting point metal, so that the low melting point metal is melted, and the low melting point metal can be suppressed from flowing out to the outside, thereby maintaining the The shape of the fuse conductor 13. Further, even at the time of melting, the high-melting-point metal can be ablated (solder-etched) by melting of the low-melting-point metal, whereby the high-melting-point metal is rapidly melted at a temperature lower than the melting point of the high-melting-point metal. Further, the soluble conductor 13 is connected to the heating element extraction electrode 16 and the first and second electrodes 11 and 12 by solder or the like. The fusible conductor 13 can be easily joined by reflow soldering. Further, the fusible conductor 13 is preferably coated with a flux 17 in order to prevent oxidation, improve wettability, and the like. [Cover Member] Further, the protective member 1 is provided with a cover member 20 on the surface 10e of the insulating substrate 10 in order to protect the inside. The cover member 20 is formed in a substantially rectangular shape in accordance with the shape of the insulating substrate 10. Moreover, as shown in FIG. 1, the cover member 20 has a side surface 21 connected to the surface 10e of the insulating substrate 10 on which the fusible conductor 13 is disposed, and a top surface 22 covering the surface 10e of the insulating substrate 10; On the surface 10e of the insulating substrate 10, there is an internal space in which the sufficiently soluble conductor 13 expands in a spherical shape upon melting, and the molten conductor is aggregated on the heating element extraction electrode 16 or the first and second electrodes 11 and 12. In the cover member 20, the side surface 21 is attached to the surface 10e of the insulating substrate 10 by an adhesive or welding. As the adhesive for the connection cover member 20, a thermosetting adhesive excellent in connection reliability can be preferably used. [Manufacturing Step] Next, the manufacturing steps of the protective element 1 will be described. First, the first and second electrodes 11 and 12, the heating element 14, the first and second heating element electrodes 18 and 19, the insulating member 15, and the heating element extraction electrode 16 are formed on the surface 10e of the insulating substrate 10. Further, the external connection electrodes 11a, 12a, and 18b are formed on the back surface 10f of the insulating substrate 10, and are connected to the first and second electrodes 11 and 12 and the first heating element electrode 18 via a castle-type structure or a hole portion 25. Then, the meltable conductor 13 is mounted across the heating element extraction electrode 16 across the first and second electrodes 11 and 12. Further, a connection solder may be supplied between the soluble conductor 13 and the first and second electrodes 11 and 12 and the heating element extraction electrode 16. Next, the cover member 20 is attached to the surface 10e of the insulating substrate 10. The connection of the lid member 20 is preferably performed by supplying a thermosetting adhesive having excellent joint strength to the lower portion of the side surface 21. Then, the structure of the cover member 20 on the surface 10e of the insulating substrate 10 is heat-treated, and the soluble conductor 13 is connected to the first and second electrodes 11 and 12 and the heat generating body lead-out electrode 16 via the solder for connection. The cover member 20 is bonded to the surface 10e of the insulating substrate 10 by hardening the thermosetting adhesive, whereby the protective member 1 is formed. The protective element 1 is mounted on a circuit board 2 on which a power supply circuit or the like is formed by reflow or the like, thereby forming the circuit module 3. [The center of the fusible conductor coincides with the heat generating center of the heating element] At this time, the protective element 1 preferably has the fusible conductor 13 mounted so that the center of the soluble conductor 13 overlaps the heat generating center of the heating element 14. In the fusible conductor 13 formed into a rectangular plate-like body, the center of the fusible conductor 13 means the position of the center of gravity of the fusible conductor 13. The heat generating center of the heat generating body 14 is the position at which the temperature at the initial stage of the heat generation is the highest, and is referred to as the center of gravity of the heat generating body 14 in the heat generating body 14 formed in a rectangular shape. By mounting the center of the soluble conductor 13 and the heat generating center of the heating element 14, the heat of the heating element 14 can be efficiently transmitted to the soluble conductor 13, and the soluble conductor 13 can be quickly melted after the heat is generated. Moreover, by efficiently transferring the heat of the heating element 14 to the soluble conductor 13, it is possible to prevent the insulating substrate 10 or the heating element 14 from overheating, and it is possible to suppress the occurrence of cracks. [Arrangement of Each Unit] Here, the amount of heat generated by the heating element 14 is increased in accordance with the size of the heating element 14. Further, the hole portion 25 provided in the first heating element electrode 18 is relatively close to the heating element 14, and is easily affected by the thermal shock caused by the heat generation of the heating element 14. Therefore, when the fusible conductor 13 which is increased in size by the high capacity requirement of the protective element 1 is used, and the heat generation body 14 is to obtain the heat generation for rapidly melting the large-sized fusible conductor 13, there is a thermal shock toward the hole. The portion 25 is cracked on the insulating substrate or the heating element 14. In the heating element 14, the heat generation of the cracked portion is stopped, so that the desired amount of heat generation cannot be obtained, and the melting time of the meltable conductor 13 is also prolonged. Therefore, the protective element 1 is disposed such that the heating element 14 or the hole portion 25 and the like constitute the respective constituent portions of the protective element 1, thereby preventing cracking from occurring in the hole portion 25 due to thermal shock when the heating element 14 is energized and heated. Specifically, as shown in FIG. 6, the protective element 1 is provided with the first place C1 from the intermediate position C2 of the distance from the third side edge 10c to the fourth side edge 10d of the insulating substrate 10 from the heat generating center C1 of the heat generating body 14. In the second heating element electrodes 18 and 19, the side edges of the heating element electrodes having a large heat capacity are formed to be biased. As described above, since the protective element 1 is formed with the heating element extraction electrode 16 and the hole portion 25 is not formed in the second heating element electrode 19, the second heating element electrode 19 is compared with the first heating element in which the hole portion 25 is formed. The electrode 18 has a large heat capacity. Therefore, the heat generating center C1 of the heat generating body 14 of the protective element 1 is formed to be biased toward the fourth side edge 10d side on which the second heat generating body electrode 19 is provided. As a result, in the protective element 1, the heat generated by the heat generating element 14 is weakened by the thermal shock to the region between the hole portion 25 and the end portion on the third side edge 10c side of the heat generating body 14, and cracking can be prevented. Further, in the symmetrical protection element 27 in which the hole portion 26 is formed in the second heating element electrode 19 as shown in FIG. 5, the first and second heating element electrodes 18 are provided in the heat generating center of the heating element 14. In 19, the side edge side of the heating element electrode having a large heat capacity is formed to be biased. Further, the protective element 1 can be formed by defining the dimensions of the respective portions in the plan view of the protective element 1 shown in FIG. 7 as follows, in accordance with the first to seventh aspects described below. The conditions. A: the shortest distance B between the third side edge 10c of the insulating substrate 10 and the end portion on the third side edge 10c side of the heat generating body 14: the end portion on the third side edge 10c side of the heat generating body 14 and the first heat generating body The shortest distance C of the outer edge of the hole portion 25 of the electrode 18: the shortest distance D between the fourth side edge 10d of the insulating substrate 10 and the end portion on the fourth side edge 10d side of the heat generating body 14: the third through the insulating substrate 10 The center portion between the fourth side edges 10c and 10d is parallel to the distance E between the center line of the third and fourth side edges 10c and 10d and the end portion on the third side edge 10c side of the heat generating body 14: through the insulating substrate 10 The center portion between the third and fourth side edges 10c and 10d is parallel to the distance between the center line of the third and fourth side edges 10c and 10d and the end portion on the fourth side edge 10d side of the heat generating body 14: an insulating substrate The distance G between the third and fourth side edges 10c and 10d of 10: the width H of the heat generating body 14 formed into a substantially rectangular shape: the first one adjacent to the third and fourth side edges 10c and 10d of the insulating substrate 10. The distance between the second side edges 10a and 10b. Here, when B is added, when B is present in a plurality of holes 25, B means the end and the side of the third side edge 10c side of the heat generating body 14 The hole portion 25 on the side of the heating element 14 The shortest distance from the outer edge. FIG. 8 is a plan view showing the protective element 1 having the through hole formed slightly inside the third side edge 10c as the hole portion 25 provided in the first heat generating body electrode 18. In the protective element 1 shown in Fig. 8, the outer edge of the hole portion 25 becomes the outer edge of the through hole. In addition, FIG. 9 is a view showing a castle-type structure provided on the third side edge 10c and a through hole formed slightly inside the third side edge 10c as a protective member provided in the hole portion 25 of the first heat generating body electrode 18. 1 top view. In the protective element 1 shown in Fig. 9, the outer edge of the hole portion 25 is located at the outer edge of the through hole located on the side closest to the heat generating body 14. In the symmetrical protection element 27 in which the hole portion 25 is provided in the first heating element electrode 18 and the hole portion 26 is provided in the second heating element electrode 19, the first and second heating element electrodes 18, 19 and 3. In the fourth side edges 10c and 10d, the distance between the outer edge of the hole portion in which the heat generating body electrode having a small heat capacity is formed and the side edge on which the heat generating body electrode is formed is B, and heat having a large heat capacity is formed. The distance between the outer edge of the hole portion of the body electrode and the side edge on which the heat generating body electrode is formed is C. [First Aspect: B/(D+E)] The protective element 1 preferably has B/(D+E) set to 0.20 or more. In other words, the protective element 1 preferably has the shortest distance (B) between the end portion on the third side edge 10c side of the heat generating body 14 and the outer edge of the hole portion 25 provided in the first heat generating body electrode 18 with respect to the heat generating body 14. The ratio of the length (D+E) is 0.20 or more. The amount of heat generated by the heating element 14 becomes larger in accordance with the length (D+E) of the heating element 14, and the longer the distance between the heating element 14 and the hole portion 25, the greater the resistance to cracking. Further, by setting the ratio of the distance (B) of the heating element 14 to the hole portion 25 to the length (D+E) of the heating element 14 to be 0.20 or more, the resistance to heat generation of the heat generating body 14 can be improved, thereby preventing it from being prevented. The occurrence of cracks toward the hole portion 25. On the other hand, when the ratio of the distance (B) of the heating element 14 to the hole portion 25 to the length (D+E) of the heating element 14 is less than 0.20, the heating element is larger than the length (D+E) of the heating element 14. The distance from the hole portion 25 is extremely short, and the resistance to thermal shock is insufficient, and there is a crack. [Second aspect: B/G] Further, it is preferable that the protection element 1 has B/G set to 1.0 or more. In other words, the protective element 1 preferably has a shortest distance (B) between the end portion on the third side edge 10c side of the heat generating body 14 and the outer edge of the hole portion 25 with respect to the width of the heat generating body 14 formed in a substantially rectangular shape (G). The ratio is 1.0 or more. The amount of heat generated by the heating element 14 also increases in accordance with the width (G) of the heating element 14, and the wider the width, the wider the heat transfer path toward the hole portion 25, so that it is more susceptible to the influence of thermal shock. Further, the longer the distance between the heating element 14 and the hole portion 25, the greater the resistance to cracking. Therefore, by setting the ratio of the distance (B) of the heating element 14 to the hole portion 25 to the width (G) of the heating element to be 1.0 or more, it is possible to provide resistance against the heat generation of the heating element 14, and it is possible to prevent the hole from being directed toward the hole. The occurrence of the crack in the part 25. On the other hand, when the ratio of the distance (B) of the heating element 14 to the hole portion 25 to the width (G) of the heating element is less than 1.0, the heating element 14 is larger than the width (G) of the heating element 14. The distance from the hole portion 25 is extremely short, the resistance to thermal shock is insufficient, and there is a crack. [Third aspect: B/(G/(D+E))] Further, the protective element 1 preferably has B/(G/(D+E)) of 6.0 or more. That is, the protective element 1 is preferably a shortest distance (B) from the end of the third side edge 10c side of the heat generating body 14 to the outer edge of the hole portion 25 with respect to the width (G) and length (D+E) of the heat generating body 14. The ratio of the aspect ratio (G/(D+E)) is 6.0 or more. When the shortest distance (B) between the end portion on the third side edge 10c side of the heat generating body 14 and the outer edge of the hole portion 25 is large in the insulating substrate 10 of a specific size, the third and fourth portions are relatively transparent. The distance (D+E) of the heat generating body 14 provided between the side edges 10c and 10d is shortened, and the amount of heat generation is small. Further, when the width (G) of the heating element 14 is small, the amount of heat generation is small. Therefore, in the insulating substrate of a specific size, the aspect ratio (G/(D+E)) of the width (G) and the length (D+E) of the heating element 14 to the hole portion 25 is defined by the distance (B) of the heating element 14 to the hole portion 25. The ratio can be resistant to the heat generation of the heating element 14. Specifically, the ratio of the distance B between the heating element 14 and the hole portion 25 to the aspect ratio (G/(D+E)) of the width (G) of the heating element 14 and the length (D+E) is set to 6.0 or more. The resistance to the heat generation of the heating element 14 is provided, and the occurrence of cracks toward the hole portion 25 can be prevented. On the other hand, when the ratio of the distance B between the heating element 14 to the hole portion 25 with respect to the aspect ratio (G/(D+E)) of the width (G) and the length (D+E) of the heating element 14 is less than 6.0, The length of the heating element 14 (D+E) or the width (G) of the heating element 14 is such that the distance between the heating element 14 and the hole portion 25 is extremely short, and resistance to thermal shock is insufficient, and cracking occurs. [Fourth aspect: B/(B+D+E+C)] Further, the protection element 1 preferably has B/(B+D+E+C) set to 0.15 or more. That is, it is preferable that the shortest distance (B) between the end portion on the third side edge 10c side of the heat generating body 14 and the outer edge of the hole portion 25 is relative to the distance from the outer edge of the hole portion 25 to the fourth side edge 10d (B+D+E+C) The ratio is 0.15 or more. In the insulating substrate 10, since the hole portion 25 is provided on the third side edge 10c side, the resistance of the heat generating body 14 to the hole portion 25 of the insulating substrate 10 against thermal shock becomes a problem, and therefore the insulating substrate 10 is removed. The distance from the side edge 10c to the region outside the sheet portion of the hole portion 25, that is, the distance from the outer edge of the hole portion 25 to the fourth side edge 10d (B+D+E+C) can be said to be the substantial insulating substrate 10 that receives the thermal shock of the heat generating body 14. The length. Further, in the distance (B+D+E+C) from the outer edge of the hole portion 25 that receives the thermal shock of the heat generating body 14 to the fourth side edge 10d, the end portion of the third side edge 10c side of the heat generating body 14 and the outer edge of the hole portion 25 The greater the ratio of the shortest distance (B), the more resistant it is to the heat generation of the heating element 14. Specifically, by setting B/(B+D+E+C) to 0.15 or more, resistance to heat generation of the heating element 14 can be provided, and occurrence of cracks toward the hole portion 25 can be prevented. On the other hand, in the distance from the outer edge of the hole portion 25 to the fourth side edge 10d (B+D+E+C), the shortest distance (B) between the end portion on the third side edge 10c side of the heat generating body 14 and the outer edge of the hole portion 25 When the ratio is less than 0.15, the length of the substantial insulating substrate 10 (B+D+E+C) is short in the distance between the heating element 14 and the hole portion 25, and the resistance against thermal shock is insufficient, and cracking occurs. [Fifth aspect: B/C] Further, it is preferable that the protective element 1 has B/C set to 0.9 or more. In other words, in the insulating substrate 10 of a specific size, it is preferable that the shortest distance (B) between the end portion on the third side edge 10c side of the heat generating body 14 and the outer edge of the hole portion 25 is opposite to the fourth side of the insulating substrate 10. The ratio of the edge 10d to the shortest distance (C) of the end portion on the fourth side edge 10d side of the heating element 14 is 0.9 or more. When the length (D+E) of the heat generating body 14 between the third and fourth side edges 10c and 10d of the surface 10e of the insulating substrate 10 is fixed, the both ends of the heat generating body 14 and the outer edge of the hole portion 25 and the The ratio of the distance of the side edge 10d is such that the shortest distance (B) between the end portion on the third side edge 10c side of the heat generating body 14 and the outer edge of the hole portion 25 is large, and specifically, it is set to 0.9 or more. The heat generating body 14 is biased toward the fourth side edge 10d side, and the resistance of the heat generating body 14 to the hole portion 25 where the crack is likely to occur is improved against thermal shock, and the occurrence of cracks toward the hole portion 25 can be prevented. On the other hand, in the surface 10e of the insulating substrate 10, the shortest distance (B) between the end portion on the third side edge 10c side of the heat generating body 14 and the outer edge of the hole portion 25 is opposite to the fourth side edge of the insulating substrate 10. When the ratio of the shortest distance (C) of the end portion of the heating element 14 to the fourth side edge 10d side of the heating element 14 is less than 0.9, the distance between the heating element 14 and the hole portion 25 is short, and the resistance against thermal shock is insufficient. There is a crack in the crack. [Sixth aspect: B/(F-(E+C))] Further, the protective element 1 preferably has B/(F-(E+C)) set to 0.30 or more. In other words, it is preferable that the shortest distance (B) between the end portion on the third side edge 10c side of the heat generating body 14 and the outer edge of the hole portion 25 is relative to the third side edge 10c of the insulating substrate 10 to the third of the insulating substrate 10. The ratio of the distance (F-(E+C)) at the center position between the fourth side edges 10c and 10d is 0.30 or more. The distance from the third side edge 10c (F-(E+C)) indicates the center position between the third and fourth side edges 10c and 10d of the insulating substrate 10, and the distance (B) indicates the outer edge of the hole portion 25 to the heat generating body 14. The distance from the end. Therefore, B/(F-(E+C)) defines the positional relationship between the center position of the insulating substrate 10 and the end portion on the third side edge 10c side of the heat generating body 14. Further, the shortest distance (B) between the end portion on the third side edge 10c side of the heat generating body 14 and the outer edge of the hole portion 25 is provided to the third side edge 10c of the insulating substrate 10 to the third side of the insulating substrate 10. The ratio of the distance (F-(E+C)) at the center position between the fourth side edges 10c and 10d is 0.30 or more, and the turtle can easily occur in the region from the center position of the insulating substrate 10 to the side of the third side edge 10c. The region of the cracked hole portion 25 is ensured to have a length against the thermal shock of the heat generating body 14, so that the occurrence of cracks toward the hole portion 25 can be prevented. On the other hand, the shortest distance (B) between the end portion on the third side edge 10c side of the heating element 14 and the outer edge of the hole portion 25 is the third edge 10c of the insulating substrate 10 to the third of the insulating substrate 10, When the ratio of the distance (F-(E+C)) at the center position between the fourth side edges 10c and 10d is less than 0.30, the heat generating body 14 is in the region from the center position of the insulating substrate 10 to the side of the third side edge 10c. The distance between the holes 25 is short, the resistance to thermal shock is insufficient, and there is a crack. Further, the distance from the third side edge 10c of the insulating substrate 10 to the center position between the third and fourth side edges 10c and 10d of the insulating substrate 10 may be defined as (A+) in addition to (F-(E+C)). D) or (F/2). [Seventh aspect: {B+(D+E)/2}/{(B+C+D+E)/2}] Further, the protective element 1 preferably has the outer edge of the hole portion 25 to the center of the heat generating body 14. The ratio of the distance {(B+C+D+E)/2} of the distance {B+(D+E)/2} from the outer edge of the hole portion 25 to the fourth side edge 10d of the insulating substrate 10 {B+( D+E)/2}/{(B+C+D+E)/2} is 0.99 or more. The distance {(B+C+D+E)/2} from the outer edge of the hole portion 25 to the half length of the fourth side edge 10d of the insulating substrate 10 indicates the center of the substantial insulating substrate 10, and is obtained by The ratio of the distance from the outer edge of the hole portion 25 to the center of the heat generating body 14 is {B + (D + E) / 2}, and the position of the heat generating center in the substantial insulating substrate 10 is defined. Further, the heat generating body 14 is formed in such a manner that {B+(D+E)/2}/{(B+C+D+E)/2} becomes 0.99 or more, and the heat generating body 14 has a heat generating center and a substantial insulating substrate. The center of 10 is substantially uniform or biased toward the side of the fourth side edge 10d. Therefore, the length of the heat-resistant body 14 to the hole portion 25 can be ensured to have a resistance against the thermal shock of the heat generating body 14, and the occurrence of cracks toward the hole portion 25 can be prevented. On the other hand, the distance from the outer edge of the hole portion 25 to the center of the heat generating body 14 is {B+(D+E)/2} with respect to the half length of the outer edge of the hole portion 25 to the fourth side edge 10d of the insulating substrate 10. When the ratio of {(B+C+D+E)/2} is less than 0.99, the heat generating center of the heating element 14 is biased from the center of the substantial insulating substrate toward the third side edge 10c side, and is not heated. The body region of the body 14 to the hole portion 25 is ensured to have a length against the thermal shock of the heat generating body 14, and there is a possibility that cracking occurs toward the hole portion 25. [Circuit Substrate] Next, the circuit board 2 on which the protective element 1 is mounted will be described. As the circuit board 2, for example, a rigid substrate such as a glass epoxy substrate, a glass substrate or a ceramic substrate, or a known insulating substrate such as a flexible substrate can be used. Further, as shown in FIG. 2, the circuit board 2 has a mounting portion on which the protective element 1 is surface-mounted by reflowing or the like, and is provided with an external connection electrode to the back surface 10f of the insulating substrate 10 provided on the protective element 1 in the mounting portion. Connecting electrodes connected to 11a, 12a, and 18b. Further, an element such as an FET that energizes the heating element 14 of the protective element 1 is attached to the circuit board 2. [Method of Using Circuit Module] Next, a method of using the protective element 1 and the circuit module 3 in which the surface of the protective element 1 is mounted on the circuit board 2 will be described. As shown in FIG. 10, the circuit module 3 can be used, for example, as a circuit in a battery pack of a lithium ion battery. For example, the protective element 1 is used by being assembled to a battery pack 50 having a battery stack 55 containing battery cells 51 to 54 of a total of four lithium ion batteries. The battery pack 50 includes: a battery stack 55; a charge and discharge control circuit 60 that controls charging and discharging of the battery stack 55; and a protective element 1 of the present invention that blocks charging when the battery stack 55 is abnormal; the detecting circuit 56 detects The voltage of each of the battery cells 51 to 54 and the current control element 57 control the operation of the protection element 1 based on the detection result of the detection circuit 56. The battery stack 55 is detachably connected to the charging device 65 via the positive electrode terminal 50a and the negative electrode terminal 50b of the battery pack 50, in which the battery cells 51 to 54 which are subjected to the protection control so as not to be overcharged and overdischarged are connected in series. The charging voltage from the charging device 65 is applied. The positive electrode terminal 50a and the negative electrode terminal 50b of the battery pack 50, which is charged by the charging device 65, are connected to an electronic device to be operated by the battery, whereby the electronic device can be operated. The charge and discharge control circuit 60 includes two current control elements 61 and 62 connected in series to a current path flowing from the battery stack 55 to the charging device 65, and a control unit 63 that controls the operations of the current control elements 61 and 62. . The current control elements 61 and 62 include, for example, an electric field effect transistor (hereinafter referred to as an FET), and control the conduction direction of the current path to the battery stack 55 and/or the discharge direction by controlling the gate voltage by the control unit 63. And block. The control unit 63 operates by receiving power supply from the charging device 65, and controls the current control element 61 such that the current path is blocked when the battery stack 55 is overdischarged or overcharged based on the detection result detected by the detection circuit 56. 62 action. The protection element 1 is connected, for example, to a charge and discharge current path between the battery stack 55 and the charge and discharge control circuit 60, and its operation is controlled by the current control element 57. The detection circuit 56 is connected to each of the battery cells 51 to 54 to detect the voltage values of the battery cells 51 to 54 and supply the respective voltage values to the control unit 63 of the charge and discharge control circuit 60. Further, the detection circuit 56 outputs a control signal for controlling the current control element 57 when any one of the battery cells 51 to 54 becomes an overcharge voltage or an overdischarge voltage. The current control element 57 includes, for example, an FET, and operates the protection element 1 when the voltage values of the battery cells 51 to 54 become a voltage exceeding a state of overdischarge or overcharge according to a detection signal output from the detection circuit 56. How the switching operations of the current control elements 61 and 62 both control the manner in which the charge and discharge current paths of the battery stack 55 are blocked. In the battery pack 50 including the above configuration, the configuration of the protective element 1 will be specifically described. First, the protective element 1 to which the present invention is applied has a circuit configuration as shown in FIG. In other words, the protective element 1 includes a circuit configuration of a fusible conductor 13 connected in series via the heating element extraction electrode 16 and a heating element 14 that is energized by the connection point of the soluble conductor 13 and generates heat. The fusible conductor 13 is melted. Further, in the protective element 1, for example, the soluble conductor 13 is connected in series to the charge and discharge current path, and the heat generating body 14 is connected to the current control element 57. The first electrode 11 of the protective element 1 is connected to the open end of the battery stack 55 via the external connection electrode 11a, and the second electrode 12 is connected to the open end of the battery pack 50 on the positive electrode terminal 50a side via the external connection electrode 12a. Further, the heating element 14 is connected to the charge and discharge current path of the battery pack 50 via the heating element extraction electrode 16 and the soluble conductor 13, and is further connected to the current control element 57 via the first heating element electrode 18 and the external connection electrode 18b. connection. When the heating element 14 of the protective element 1 is energized and generates heat, the soluble conductor 13 is melted, and the battery pack 50 is towed to the heating element extraction electrode 16 by its wettability. As a result, the protective element 1 can reliably block the current path by the fusible conductor 13 being blown. Further, since the power supply path to the heating element 14 is also blocked by the meltable conductor 13, the heat generation of the heating element 14 is also stopped. Further, when the battery pack 50 has a large current exceeding the expected value of the protection element 1 in the charge and discharge path, the current can be blocked by blowing the fusible conductor 13 by self-heating (Joule heat). path. As described above, since the protective element 1 is disposed such that the heating element 14 or the hole portion 25 and the like constitute the respective constituent portions of the protective element 1, it is possible to prevent cracking from occurring in the hole portion 25 due to thermal shock when the heating element 14 is energized and heated. Further, heat generation of the heat generating body 14 can be efficiently transmitted to the soluble conductor 13. Therefore, the protective element 1 can obtain a desired amount of heat generation when the heating element 14 is energized and heated, thereby stably maintaining the fusing characteristics of the fusible conductor 13. Furthermore, the protection element 1 to which the present technology is applied is not limited to the case of being used in a battery pack of a lithium ion battery, and can of course be applied to avoid abnormal overheating of an integrated circuit (IC), etc., which is required to be blocked by an electrical signal. Various uses of the breaking current path. [Embodiment] Next, an embodiment of the present technology will be described. In the present embodiment, samples of Examples 1 to 3 and Comparative Examples 1 to 5 which changed the size and arrangement of the respective portions A to H of the protective element 1 were formed, and it was confirmed that cracks occurred when the heating element (electric power: 33 W) was heated. Whether there is. In the case where the crack occurs in either of the insulating substrate or the heating element, it is referred to as "Yes". The protective element of each sample was an asymmetric type formed by using a rectangular ceramic substrate (length F: 9.5 mm, width H: 5.0 mm) as the insulating substrate 10, and two in the longitudinal direction of the insulating substrate 10. The third and fourth side edges 10c and 10d on the side form the first and second heat generating body electrodes 18 and 19, and the first heat generating body electrode 18 formed on the third side edge 10c side forms a castle-shaped structure as a hole portion. 25, the heating element extraction electrode 16 is connected to the second heating element electrode 19 formed on the fourth side edge 10d side. The dimensions of the samples of the respective examples and comparative examples are shown in Table 1, and the numerical values in the first to seventh aspects and the presence or absence of crack occurrence are shown in Table 2. [Table 1] [Table 2] [First embodiment: B/(D+E)] In the first to third embodiments, the end portion on the third side edge 10c side of the heat generating body 14 and the outer edge of the hole portion 25 provided in the first heat generating body electrode 18 are provided. The ratio (B/(D+E)) of the shortest distance B to the length (D+E) of the heating element 14 is 0.20 or more, and the resistance against the heat generation of the heating element 14 is improved, and cracking toward the hole portion 25 does not occur. In Comparative Examples 1 to 5, (B/(D+E)) was less than 0.20, and the distance between the heating element 14 and the hole portion 25 was short compared to the length (D+E) of the heating element 14, and the resistance against thermal shock was insufficient. , so that cracks have occurred. [Second aspect: B/G] In the first to third embodiments, the shortest distance (B) between the end portion on the third side edge 10c side of the heat generating body 14 and the outer edge of the hole portion 25 is formed to be substantially rectangular. The ratio of the width (G) of the heating element 14 is 1.0 or more, and the resistance to the heat generation of the heating element 14 is provided, so that the crack toward the hole portion 25 does not occur. In Comparative Examples 1 to 5, (B/G) was less than 1.0, and the distance between the heat generating body 14 and the hole portion 25 was short compared to the width (G) of the heat generating body 14, and the resistance against thermal shock was insufficient. Cracks have occurred. [Third aspect: B/(G/(D+E))] In the first to third embodiments, the shortest distance between the end portion on the third side edge 10c side of the heat generating body 14 and the outer edge of the hole portion 25 (B) The ratio of the aspect ratio (G/(D+E)) of the width (G) to the length (D+E) of the heating element 14 is 6.0, and is comparable to the heating element in the insulating substrate 10 of a specific size (9.5 × 5.0 mm). The aspect ratio (G/(D+E)) of the width (G) and the length (D+E) of 14 ensures that only the distance (B) of the heat generating body 14 to the hole portion 25 against the heat generation of the heat generating body 14 is provided, thereby preventing The occurrence of cracks toward the hole portion 25. On the other hand, in Comparative Examples 1 to 5, B/(G/(D+E)) was less than 6.0, and the heating element 14 was compared with the length (D+E) of the heating element 14 or the width (G) of the heating element 14. The distance between the holes 25 is extremely short, and the resistance to thermal shock is insufficient, so that cracking occurs. [Fourth Aspect: B/(B+D+E+C)] In the first to third embodiments, the shortest distance (B) between the end portion on the third side edge 10c side of the heat generating body 14 and the outer edge of the hole portion 25 is relative to the hole portion. The ratio of the distance from the outer edge to the fourth side edge (B+D+E+C) is 0.15 or more. Therefore, the shortest distance (B) between the end portion on the third side edge 10c side of the heating element 14 and the outer edge of the hole portion 25 is relatively resistant. The thermal shock of the heating element 14 has a large ratio of the length of the insulating substrate 10, and has resistance against the heat generation of the heating element 14, so that cracking toward the hole portion 25 does not occur. On the other hand, in Comparative Examples 1 to 5, B/(B+D+E+C) was less than 0.15, and the length of the insulating substrate 10 (B+D+E+C) was substantially the end of the third side edge 10c side of the heating element 14 and the hole portion 25. The shortest distance (B) of the outer edge is short, and the resistance to thermal shock is insufficient, so that cracking occurs. [Fifth Aspect: B/C] In the first to third embodiments, the end portion of the heat generating body 14 on the third side edge 10c side and the hole portion 25 in the insulating substrate 10 having a specific size (9.5 × 5.0 mm) The shortest distance (B) of the outer edge is 0.9 or more with respect to the shortest distance (C) of the fourth side edge 10d and the end portion of the heating element 14 on the fourth side edge 10d side, and the heating element 14 is directed to the fourth side edge. The 10d side is formed to be biased, whereby the heat generating body 14 is improved in resistance to thermal shock in the region of the hole portion 25 where cracking is likely to occur, so that cracking toward the hole portion 25 does not occur. On the other hand, in Comparative Examples 1 to 5, B/C was less than 0.9, and the shortest distance (B) between the end portion on the third side edge 10c side of the heat generating body 14 and the outer edge of the hole portion 25 was short, against heat. The impact resistance is insufficient and cracking occurs. [Sixth aspect: B/(F-(E+C))] In the first to third embodiments, the shortest distance between the end portion on the third side edge 10c side of the heat generating body 14 and the outer edge of the hole portion 25 (B) The ratio of the distance (F-(E+C)) from the third side edge 10c of the insulating substrate 10 to the center position between the third and fourth side edges 10c and 10d of the insulating substrate 10 is 0.30 or more, and is in the insulating substrate 10. The hole portion 25 in which the crack is likely to occur in the region from the center position to the third side edge 10c is ensured to have a resistance against the thermal shock of the heat generating body 14, so that the crack toward the hole portion 25 does not occur. On the other hand, in Comparative Examples 1 to 5, B/(F-(E+C)) was less than 0.30, and the third side edge of the heating element 14 was in the region from the center position of the insulating substrate 10 to the side of the third side edge 10c. The shortest distance (B) between the end portion of the 10c side and the outer edge of the hole portion 25 is short, and the resistance against thermal shock is insufficient, and cracking occurs. [Seventh aspect: about {B+(D+E)/2}/{(B+C+D+E)/2}] In the first to third embodiments, the outer edge of the hole portion 25 is at the center of the heating element 14. The ratio of the distance {(B+C+D+E)/2} of the distance {B+(D+E)/2} from the outer edge of the hole portion 25 to the fourth side edge 10d of the insulating substrate 10 {B+( D+E)/2}/{(B+C+D+E)/2} is 0.99 or more, and the heat generating center of the heating element 14 substantially coincides with the center of the substantial insulating substrate 10 or is biased toward the fourth side edge 10d side. Therefore, it is possible to ensure the length of the resistance against the thermal shock of the heating element 14 in the heat generating center of the heating element 14 to the hole portion 25, and no cracking toward the hole portion 25 occurs. On the other hand, in Comparative Examples 1 to 5, {B + (D + E) / 2} / {(B + C + D + E) / 2} was less than 0.99, and the heat generating center of the heating body 14 was a substantial insulating substrate. The center is biased toward the third side edge 10c side, and it is impossible to ensure the length of the heat-resistant body 14 to the hole portion 25 in the sheet region to withstand the thermal shock resistance of the heat generating body 14, and cracking toward the hole portion 25 occurs.
1‧‧‧保護元件1‧‧‧Protection components
2‧‧‧電路基板2‧‧‧ circuit board
3‧‧‧電路模組3‧‧‧Circuit Module
10‧‧‧絕緣基板10‧‧‧Insert substrate
10a‧‧‧第1側緣10a‧‧‧1st edge
10b‧‧‧第2側緣10b‧‧‧2nd edge
10c‧‧‧第3側緣10c‧‧‧3rd edge
10d‧‧‧第4側緣10d‧‧‧4th edge
10e‧‧‧表面10e‧‧‧ surface
10f‧‧‧背面10f‧‧‧back
11‧‧‧第1電極11‧‧‧1st electrode
11a‧‧‧外部連接電極11a‧‧‧External connection electrode
12‧‧‧第2電極12‧‧‧2nd electrode
12a‧‧‧外部連接電極12a‧‧‧External connection electrode
13‧‧‧可熔導體13‧‧‧Solid conductor
14‧‧‧發熱體14‧‧‧heating body
15‧‧‧絕緣構件15‧‧‧Insulating components
16‧‧‧發熱體引出電極16‧‧‧heating body extraction electrode
17‧‧‧助熔劑17‧‧‧ Flux
18‧‧‧第1發熱體電極18‧‧‧1st heating element electrode
18a‧‧‧連接邊18a‧‧‧Connecting side
19‧‧‧第2發熱體電極19‧‧‧2nd heating element electrode
19a‧‧‧連接邊19a‧‧‧Connecting side
20‧‧‧蓋構件20‧‧‧Cover components
21‧‧‧側面21‧‧‧ side
22‧‧‧頂面22‧‧‧ top surface
25‧‧‧孔部25‧‧‧ Hole Department
26‧‧‧孔部26‧‧‧ Hole Department
27‧‧‧保護元件27‧‧‧Protection components
50‧‧‧電池組50‧‧‧Battery Pack
50a‧‧‧正極端子50a‧‧‧positive terminal
50b‧‧‧負極端子50b‧‧‧Negative terminal
51～54‧‧‧電池單元51～54‧‧‧ battery unit
55‧‧‧電池堆55‧‧‧Battery stack
56‧‧‧檢測電路56‧‧‧Detection circuit
57‧‧‧電流控制元件57‧‧‧ Current control components
60‧‧‧充放電控制電路60‧‧‧Charge and discharge control circuit
61‧‧‧電流控制元件61‧‧‧ Current control components
62‧‧‧電流控制元件62‧‧‧ Current control components
63‧‧‧控制部63‧‧‧Control Department
65‧‧‧充電裝置65‧‧‧Charging device
90‧‧‧保護元件90‧‧‧Protection components
91‧‧‧第1電極91‧‧‧1st electrode
92‧‧‧第2電極92‧‧‧2nd electrode
93‧‧‧可熔導體93‧‧‧Solid conductor
94‧‧‧發熱體94‧‧‧heating body
95‧‧‧發熱體引出電極95‧‧‧heating body extraction electrode
97‧‧‧蓋構件97‧‧‧Cover components
98‧‧‧助熔劑98‧‧‧ Flux
A‧‧‧距離A‧‧‧ distance
B‧‧‧距離B‧‧‧ distance
C‧‧‧距離C‧‧‧ distance
C1‧‧‧發熱中心C1‧‧‧Fever Center
C2‧‧‧中間位置C2‧‧‧ intermediate position
D‧‧‧距離D‧‧‧Distance
E‧‧‧距離E‧‧‧ distance
F‧‧‧距離F‧‧‧ distance
G‧‧‧寬度G‧‧‧Width
H‧‧‧距離H‧‧‧ distance
圖1係表示應用本技術之保護元件之外觀立體圖。 圖2係表示應用本技術之電路模組之剖視圖。 圖3係將蓋構件省略而表示保護元件之絕緣基板之表面上之俯視圖。 圖4係自背面側表示應用本技術之保護元件之外觀立體圖。 圖5係表示於第3側緣及第4側緣側形成有孔部之保護元件之俯視圖。 圖6係表示絕緣基板中心與發熱體之中心之俯視圖。 圖7係表示測量保護元件之各構成尺寸之部位之俯視圖。 圖8係表示具有形成於較第3側緣稍靠內側之通孔作為設置於第1發熱體電極之孔部的保護元件之俯視圖。 圖9係表示具有設置於第3側緣之城堡型結構、及形成於較第3側緣稍靠內側之通孔作為設置於第1發熱體電極之孔部的保護元件之俯視圖。 圖10係表示使用有應用本發明之保險絲元件之電池電路之一構成例的電路圖。 圖11係應用本發明之保險絲元件之電路圖。 圖12係表示先前之保護元件之圖，(A)係將蓋構件省略而表示之俯視圖，(B)係剖視圖。Fig. 1 is a perspective view showing the appearance of a protective member to which the present technology is applied. 2 is a cross-sectional view showing a circuit module to which the present technology is applied. Fig. 3 is a plan view showing the surface of the insulating substrate of the protective element, which is omitted from the cover member. Fig. 4 is a perspective view showing the appearance of a protective member to which the present technology is applied from the back side. Fig. 5 is a plan view showing a protective element in which a hole portion is formed on the third side edge and the fourth side edge side. Fig. 6 is a plan view showing the center of the insulating substrate and the center of the heat generating body. Fig. 7 is a plan view showing a portion where each constituent size of the protective member is measured. 8 is a plan view showing a protective element having a through hole formed slightly inside the third side edge as a hole portion provided in the first heat generating body electrode. FIG. 9 is a plan view showing a castle-type structure provided on the third side edge and a through hole formed on the inner side of the third side edge as a protective element provided in the hole portion of the first heat generating body electrode. Fig. 10 is a circuit diagram showing an example of a configuration of a battery circuit using a fuse element to which the present invention is applied. Figure 11 is a circuit diagram of a fuse element to which the present invention is applied. Fig. 12 is a view showing a conventional protective element, (A) is a plan view showing a cover member omitted, and (B) is a cross-sectional view.