Molex的矩形连接器 - 针座，公插针_正品采购_价格信息

品牌是'Molex' (10000)

产品型号	品牌	数据表	库存	价格(含增值税)	数量	工厂交货时间	触点镀层	底架	安装类型	引脚数	触点形状	外壳材料	材料	房屋材料	安装选项1	板安装选项							操作温度	包装	已出版	系列	JESD-609代码	无铅代码	零件状态	湿度敏感性等级(MSL)	终端	ECCN 代码	连接器类型	定位的数量	最高工作温度	最小工作温度	颜色	应用	行数	性别	附加功能	HTS代码	紧固类型	电压 - 额定直流	MIL一致性	符合 DIN 标准	IEC一致性	过滤功能	触点类型	混合接触	选项	额定电流	螺距	触头总数	方向	端子间距	深度	绝缘高度	样式	已加载定位数量	Reach合规守则	额定电流	间距 - 配套	绝缘颜色	导体数量	参考标准	电压 - 额定交流	可靠性	本体长度/直径	行间距-交配	触点长度 - 柱子	护罩,护罩	PCB行数	螺纹距离	接头数量	触点表面处理 - 柱子	PCB接触图案	配套信息	本体宽度	触点性别	UL可燃性规范	房屋颜色	引线长度	空壳	本体深度	额定电流（信号）	接触总长度	触点样式	触点电阻	绝缘电阻	配套触点间距	主体/外壳样式	弱电	电路数量	最大额定电压（交流）	偏振键	介电耐压	PCB 触点行距	耐用性	极数	最大额定电压（直流）	触点图案	插入力-最大值	拉坯力 - 最小值	无卤素	配套立柱长度	行数	电压-测试	符合辉光线	电压-工作	特征	直径	高度	长度	宽度	电镀厚度	触点表面处理厚度 - 配套	触点表面处理厚度 - 柱子	长度 - 终端	堆栈高度（配接）	材料可燃性等级	辐射硬化	达到SVHC
5055670471	Molex	数据表	36000 In Stock	-	最小起订量: 1 最小包装量: 1	14 Weeks	Surface Mount, Right Angle		Square						Tin	Brass	Polyamide (PA), Nylon, Glass Filled	50VAC/DC			-40°C~105°C	Tape & Reel (TR)		Micro-Lock PLUS 505567			活跃	1 (Unlimited)	Solder	EAR99	Header	4				Automotive, General Purpose, Industrial				锁定坡道						公母针								0.154 3.90mm	Board to Cable/Wire	All		因导线规格而异	0.049 1.25mm	Black								Shrouded - 4 Wall																																			1				Solder Retention						39.4μin 1.00μm	39.4μin 1.00μm			UL94 V-0			ROHS3 Compliant
87832-3420	Molex	数据表	9 In Stock	-	最小起订量: 1 最小包装量: 1	9 Weeks	Gold	表面贴装		Thermoplastic			3.5814mm	Brass							2009		e3	yes	活跃		Solder	EAR99	公母针	34	105°C	-55°C	Black		Male	套管	8536.69.40.40		125V	NO	NO	NO	NO		NO	GENERAL PURPOSE	2mm	34	Vertical							2A			ONE	UL		COMMERCIAL	1.443 inch	2.0066 mm			2	2mm			RECTANGULAR	MULTIPLE MATING PARTS AVAILABLE			94V-0					1A		SQ PIN-SKT	30mOhm	1GOhm		RECEPTACLE				CTR W/GUIDE SLOTS	500VAC V		100 Cycles			RECTANGULAR					2		Non-compliant							15μin						无	Unknown	符合RoHS标准	UL94 V-0
0705550051	Molex	数据表	N/A	-	最小起订量: 1 最小包装量: 1	5 Weeks	Gold	通孔	Through Hole, Right Angle	Square		Brass	Polyester			Gold	0.240 6.10mm	磷青铜	Polyester, Glass Filled	250V		-40°C~105°C	Tube		SL 70555			活跃	1 (Unlimited)	Solder		Header	17	105°C	-40°C	Black	Automotive, General Purpose, Industrial, Medical				插销座						公母针			2.54mm		直角		13.59mm	0.215 5.45mm	Board to Cable/Wire	All		3A	0.100 2.54mm	Black							0.130 3.30mm	Shrouded - 4 Wall			17	Tin						Black							15mOhm					16													1				电路板指南			46.63mm			15.0μin 0.38μm	74.8μin 1.90μm			UL94 V-0			ROHS3 Compliant
22-10-2081	Molex	数据表	37 In Stock	-	最小起订量: 1 最小包装量: 1	7 Weeks	Gold	通孔		Nylon			7.493mm	Brass						Bulk	2011		e3	yes	活跃		Solder	EAR99	公母针		75°C	0°C	White			STACKED			250V	NO	NO	NO	NO		NO	GENERAL PURPOSE	2.54mm		Vertical							4A			ONE	UL, CSA		COMMERCIAL					1	2.54mm	8		RECTANGULAR	MULTIPLE MATING PARTS AVAILABLE		Male	94V-0					4A		SQ PIN-SKT	10mOhm	50GOhm		RECEPTACLE							25 Cycles			RECTANGULAR		.556 N	低卤素		1		Non-compliant				3.3mm	20.1mm		20μin						无		符合RoHS标准	UL94 V-0	无铅
1053101210	Molex	数据表	1 In Stock	1: ¥21.755583 10: ¥20.524132 100: ¥19.362388 500: ¥18.266406 查看所有的价格 -	最小起订量: 1 最小包装量: 1	12 Weeks	通孔		Square						Gold	Brass	Liquid Crystal Polymer (LCP)	250V			-40°C~105°C	Tray	2016	Nano-Fit 105310			活跃	不适用	Kinked Pin, Solder	EAR99	Header	10				Automotive, General Purpose, Industrial, Medical, Military, Telecommunications			8536.69.40.30	插销座						公母针									0.356 9.05mm	Board to Cable/Wire	All			0.098 2.50mm	Black						0.098 (2.50mm)	0.126 3.20mm	Shrouded - 4 Wall				Tin																															2				电路板指南						15.0μin 0.38μm	59.0μin 1.50μm		21.30mm				ROHS3 Compliant
0878312228	Molex	数据表	N/A	-	最小起订量: 1 最小包装量: 1	10 Weeks	Gold	通孔	通孔	Square		Nylon			Gold	0.141 3.60mm	磷青铜	Polyamide (PA), Nylon, Glass Filled				Tube		Milli-Grid 87831			活跃	1 (Unlimited)	Solder		Header	22	105°C	-55°C	Black	Automotive, General Purpose, Telecommunications				插销座						公母针			2mm		Vertical		6.3mm	0.252 6.40mm	板对板或电缆	All		2A	0.079 2.00mm	Black						0.079 (2.00mm)	0.098 2.50mm	Shrouded - 4 Wall			22	Tin						Black												22													2				Board Guide, Keying Slot			24.65mm			15.0μin 0.38μm	74.8μin 1.90μm			UL94 V-0			ROHS3 Compliant
1718571008	Molex	数据表	3345 In Stock	1: ¥16.911595 10: ¥15.954339 100: ¥15.051263 500: ¥14.199305 查看所有的价格 -	最小起订量: 1 最小包装量: 1	10 Weeks		Through Hole, Right Angle		Square				LOCKING		Gold	0.265 6.73mm	Brass	Polyamide (PA), Nylon	-40°C			Bulk	2013	KK 171857			活跃	1 (Unlimited)	Solder		Header	8				Automotive, General Purpose, Medical, Telecommunications				摩擦锁						公母针							2.54mm		0.250 6.35mm	板对板或电缆	All			0.100 2.54mm	Black	ONE	UL, CSA		COMMERCIAL			0.100 2.54mm	Shrouded - 1 Wall	1			Tin	RECTANGULAR		0.25 inch						0.442 inch																		2.502 N				1										15.0μin 0.38μm	100.0μin 2.54μm			UL94 V-2			ROHS3 Compliant
0026481112	Molex	数据表	334 In Stock	1: ¥8.758723 10: ¥8.262944 100: ¥7.795234 500: ¥7.353989 查看所有的价格 -	最小起订量: 1 最小包装量: 1	通孔	Through Hole, Right Angle		Square			Polyester			Tin	0.573 14.55mm	Brass	Polyester, Glass Filled				Bulk		KK 41662	e3	yes	活跃	1 (Unlimited)	Solder		Header, Breakaway		105°C	-40°C		Automotive, General Purpose, Industrial, Medical, Telecommunications	Male	POLARIZED		Push-Pull	250V	NO	NO	NO	NO	公母针	NO				Right Angle, Vertical		18.42mm	0.128 3.25mm	板对板或电缆	All		7A	0.156 3.96mm								0.184 4.67mm	Unshrouded		3.96mm	11						94V-0	Black							6mOhm						250V												1							42.44mm			60.0μin 1.52μm	60.0μin 1.52μm			UL94 V-0			ROHS3 Compliant		无铅
1510481211	Molex	数据表	3704 In Stock	1: ¥13.122104 10: ¥12.379343 100: ¥11.678628 500: ¥11.017572 查看所有的价格 -	最小起订量: 1 最小包装量: 1	12 Weeks	通孔		Square						Tin	0.348 8.85mm	Copper Alloy	Polyamide (PA), Nylon, Glass Filled				Tray	2015	CP-6.5 151048		yes	活跃	1 (Unlimited)	Kinked Pin, Solder	EAR99	Header	2				General Purpose, Industrial				8536.69.40.30	插销座						公母针									0.630 16.00mm	Board to Cable/Wire	All				Natural						0.256 (6.50mm)	0.150 3.81mm	Shrouded - 4 Wall																																							电路板指南						50.0μin 1.27μm				UL94 V-0			ROHS3 Compliant
1722982208	Molex	数据表	1347 In Stock	1: ¥8.630864 10: ¥8.142327 100: ¥7.681443 500: ¥7.246638 查看所有的价格 -	最小起订量: 1 最小包装量: 1	14 Weeks	通孔	通孔	Square						Gold	Copper Alloy	Liquid Crystal Polymer (LCP)	400V			-40°C~120°C	Bulk	2015	Ultra-Fit 172298			活跃	1 (Unlimited)	Kinked Pin, Solder	EAR99	Header	8				Automotive, General Purpose, Industrial, Lighting, Medical, Military, Telecommunications				插销座						公母针									0.465 11.80mm	Board to Cable/Wire	All	unknown		0.138 3.50mm	Natural						0.181 (4.60mm)	0.126 3.20mm	Shrouded - 4 Wall				Tin																															2				电路板指南						15.0μin 0.38μm	60.0μin 1.52μm		26.99mm	UL94 V-0			ROHS3 Compliant
90121-0770	Molex	数据表	1595 In Stock	-	最小起订量: 1 最小包装量: 1	9 Weeks	Gold	通孔	Glass, Polyester	Polyester			6.7564mm	Brass						Bulk	2002		e3	yes			Solder		公母针		125°C	-55°C	Black		Male	C-GRID III			350V	NO	NO	NO	NO		NO	GENERAL PURPOSE	2.54mm	10	直角							3A			ONE	UL	350V	COMMERCIAL					1	2.54mm			RECTANGULAR	MULTIPLE MATING PARTS AVAILABLE								3A		SQ PIN-SKT	20mOhm	5GOhm		RECEPTACLE		9			350VDC V			10		RECTANGULAR					1		Non-compliant	350V												无	Unknown	符合RoHS标准		无铅
1722991204	Molex	数据表	2149 In Stock	1: ¥13.818665 10: ¥13.036478 100: ¥12.298559 500: ¥11.602417 查看所有的价格 -	最小起订量: 1 最小包装量: 1	13 Weeks	通孔		Square						Gold	Copper Alloy	Liquid Crystal Polymer (LCP)	400V			-40°C~120°C	Bulk	2015	Ultra-Fit 172299		yes	活跃	1 (Unlimited)	Solder	EAR99	Header	4				Automotive, General Purpose, Industrial, Lighting, Medical, Military, Telecommunications				插销座						公母针									0.465 11.80mm	Board to Cable/Wire	All			0.138 3.50mm	Black						0.181 (4.60mm)	0.126 3.20mm	Shrouded - 4 Wall				Tin																															2				Board Guide, Solder Retention						15.0μin 0.38μm	60.0μin 1.52μm		26.99mm	UL94 V-0			ROHS3 Compliant
1722862208	Molex	数据表	43 In Stock	1: ¥21.038773 10: ¥19.847894 100: ¥18.724428 500: ¥17.664559 查看所有的价格 -	最小起订量: 1 最小包装量: 1	16 Weeks	通孔	通孔	Square						Gold	Copper Alloy	Liquid Crystal Polymer (LCP)	600V			-40°C~120°C	Bulk	2014	Ultra-Fit 172286			活跃	1 (Unlimited)	Kinked Pin, Solder	EAR99	Header	8				Automotive, General Purpose, Industrial, Lighting, Medical, Military, Telecommunications				插销座						公母针									0.465 11.80mm	板对板或电缆	All	unknown		0.138 3.50mm	Natural							0.126 3.20mm	Shrouded - 4 Wall				Tin																															1				电路板指南						15.0μin 0.38μm	60.0μin 1.52μm		26.99mm	UL94 V-0			ROHS3 Compliant
39-29-9247	Molex	数据表	56 In Stock	1: ¥46.004430 10: ¥43.400406 100: ¥40.943783 500: ¥38.626206 查看所有的价格 -	最小起订量: 1 最小包装量: 1	8 Weeks	Tin	通孔	POLYAMIDE66	Nylon		Brass								2007		e3	yes	活跃		Solder	EAR99	公母针	24	105°C	-40°C	Natural			MINI-FIT JR.	8536.69.40.30	Ramp	600V	NO	NO	NO	NO		NO	GENERAL PURPOSE	4.2mm	24	Vertical							6A			ONE	UL, CSA		COMMERCIAL		4.191 mm			2	4.2mm			RECTANGULAR		0.38 inch	Male	94V-0			NO	0.504 inch	6A		SQ PIN-SKT	10mOhm	1GOhm		PLUG				外壳侧	1500VAC V	5.5118 mm	30 Cycles		600.6kV	RECTANGULAR		3.1136 N	低卤素		2		Non-compliant										0.14 inch			无	Unknown	符合RoHS标准	UL94 V-0
90130-1118	Molex	数据表	N/A	1: ¥5.507168 10: ¥5.195441 100: ¥4.901360 500: ¥4.623925 查看所有的价格 -	最小起订量: 1 最小包装量: 1	9 Weeks	Tin	通孔	16	Polyester			Brass	6.7564mm							2011			yes	活跃		Solder	EAR99	公母针	18	125°C	-55°C	Black		Male	C-GRID, SHROUDED	8536.69.40.40		350V	NO	NO	NO	NO		NO	GENERAL PURPOSE	2.54mm	18	Vertical							3A			ONE	UL		COMMERCIAL		2.54 mm			2	2.54mm			RECTANGULAR		0.384 inch		94V-0				0.515 inch	3A		SQ PIN-SKT		5000000000Ohm		RECEPTACLE					700VAC V		500 Cycles		350.35kV	RECTANGULAR					2		Non-compliant										0.114 inch			无	Unknown	符合RoHS标准		无铅
0022284175	Molex	数据表	36 In Stock	1: ¥6.213553 10: ¥5.861841 100: ¥5.530042 500: ¥5.217017 查看所有的价格 -	最小起订量: 1 最小包装量: 1	11 Weeks	通孔	通孔		Square			Nylon			Gold	0.295 7.49mm	Brass	Polyamide (PA), Nylon, Glass Filled	250V			Bulk		KK 42375	e3	yes	活跃	1 (Unlimited)	Solder		Header, Breakaway					Automotive, General Purpose, Medical, Telecommunications				Push-Pull		NO	NO	NO	NO	公母针	NO				Vertical	2.54mm		0.090 2.29mm	板对板或电缆	All		4A	0.100 2.54mm	Black							0.120 3.05mm	Unshrouded			17	Tin				Male	94V-0		3.05mm				0.505 12.83mm																			7.49mm	1		Non-compliant				2.29mm	43.2mm	2.49mm		15.0μin 0.38μm	100.0μin 2.54μm			UL94 V-0			ROHS3 Compliant		无铅
0430451416	Molex	数据表	36 In Stock	1: ¥29.535227 10: ¥27.863421 100: ¥26.286248 500: ¥24.798351 查看所有的价格 -	最小起订量: 1 最小包装量: 1	7 Weeks	表面贴装	表面贴装	Square	POLYETHYLENE		Polymer			Gold	Brass	Liquid Crystal Polymer (LCP), Glass Filled	600V				Tape & Reel (TR)		Micro-Fit 3.0 43045		yes	活跃	1 (Unlimited)	Solder	EAR99	Header		105°C	-40°C		General Purpose, Medical, Military, Telecommunications		MICRO-FIT 3.0, SHROUDED, POLARIZED	8536.69.40.30	锁定坡道	250V	NO	NO	NO	NO	公母针	NO		8A			Vertical		8.77mm	0.390 9.91mm	Board to Cable/Wire	All		5A	0.118 3.00mm							0.118 (3.00mm)		Shrouded - 4 Wall		3mm	14	Tin					94V-0	Black		NO					10mOhm																		2				板锁			25.15mm			15.0μin 0.38μm	100.0μin 2.54μm			UL94 V-0			ROHS3 Compliant
0010883061	Molex	数据表	36 In Stock	1: ¥5.708898 10: ¥5.385751 100: ¥5.080898 500: ¥4.793295 查看所有的价格 -	最小起订量: 1 最小包装量: 1	7 Weeks	通孔	Through Hole, Right Angle		Square		Brass	Polyester			Tin	0.240 6.10mm	Copper Alloy	Polyester, Glass Filled	250V			Tube		C-Grid 70216	e3	yes	活跃	1 (Unlimited)	Solder		Header, Breakaway		105°C	-40°C		Automotive, General Purpose, Lighting, Medical, Telecommunications	Male			Push-Pull		NO	NO	NO	NO	公母针	NO				直角			0.220 5.60mm	板对板或电缆	All		3A	0.100 2.54mm							0.100 (2.54mm)	0.110 2.79mm	Unshrouded			6						94V-0	Black											Compliant								250.25kV						2		Non-compliant								150.0μin 3.81μm				UL94 V-0			ROHS3 Compliant	UL94 V-0	无铅
5023520810	Molex	数据表	998 In Stock	1: ¥15.551461 10: ¥14.671193 100: ¥13.840743 500: ¥13.057305 查看所有的价格 -	最小起订量: 1 最小包装量: 1	17 Weeks	表面贴装	Surface Mount, Right Angle	Square		Polyamide			Gold	Copper Alloy	Polyamide (PA), Nylon					Tape & Reel (TR)	2015	DuraClik 502352			活跃	1 (Unlimited)	Solder	EAR99	Header	8	105°C	-40°C		Automotive, Industrial				插销座						公母针					8	直角	2.0066mm	9.4mm	0.252 6.40mm	Board to Cable/Wire	All			0.079 2.00mm		ONE	UL		COMMERCIAL				Shrouded - 4 Wall	1				RECTANGULAR		0.252 inch			Natural									0.079 inch					极化外壳	500VAC V		30 Cycles								1		Non-compliant		Solder Retention			20mm							UL94 V-0			ROHS3 Compliant
0015913043	Molex	数据表	1290 In Stock	1: ¥26.142711 10: ¥24.662938 100: ¥23.266922 500: ¥21.949924 查看所有的价格 -	最小起订量: 1 最小包装量: 1	6 Weeks	Surface Mount, Right Angle		Square						Gold	0.240 6.10mm	磷青铜	Polyester, Glass Filled				Tube		SL 70634	e3	yes	活跃	1 (Unlimited)	Solder		Header	4				Automotive, General Purpose, Industrial, Medical		SL, LOW PROFILE		插销座		NO	NO	NO	NO	公母针	NO				4				0.215 5.45mm	Board to Cable/Wire	All			0.100 2.54mm	Black								Shrouded - 4 Wall				Tin																															1				电路板指南						29.5μin 0.75μm	74.8μin 1.90μm			UL94 V-0			ROHS3 Compliant
1718563002	Molex	数据表	1000 In Stock	1: ¥8.916911 10: ¥8.412183 100: ¥7.936020 500: ¥7.486812 查看所有的价格 -	最小起订量: 1 最小包装量: 1	10 Weeks	通孔		Square						Tin	0.293 7.45mm	Brass	Polyamide (PA), Nylon				Tape & Reel (TR)	2014	KK 171856			活跃	1 (Unlimited)	Solder		Header	2				Automotive, General Purpose, Medical, Telecommunications				摩擦锁						公母针									0.322 8.18mm	板对板或电缆	All			0.100 2.54mm	Black							0.092 2.34mm	Shrouded - 1 Wall															0.510 12.95mm																				1				挑选和放置						60.0μin 1.52μm	60.0μin 1.52μm			UL94 V-2			ROHS3 Compliant
0015911503	Molex	数据表	681 In Stock	1: ¥77.167556 10: ¥72.799579 100: ¥68.678849 500: ¥64.791364 查看所有的价格 -	最小起订量: 1 最小包装量: 1	7 Weeks	表面贴装	表面贴装		Square		Bronze	Thermoplastic			Gold	0.240 6.10mm	Copper Alloy	Liquid Crystal Polymer (LCP), Glass Filled	250V			Tube		C-Grid 71308	e3	yes	活跃	1 (Unlimited)	Solder		Header, Breakaway		105°C	-40°C		Automotive, General Purpose, Lighting, Medical, Telecommunications		STACKABLE		Push-Pull		NO	NO	NO	NO	公母针	NO				Vertical		5.08mm	0.090 2.29mm	板对板或电缆	All		3A	0.100 2.54mm	Black						0.100 (2.54mm)		Unshrouded			50	Tin					94V-0								15mOhm				Compliant		250V						250.25kV				低卤素		2		Non-compliant		电路板指南			63.5mm			30.0μin 0.76μm	74.8μin 1.90μm			UL94 V-0			ROHS3 Compliant	UL94 V-0
39-29-1228	Molex	数据表	20 In Stock	1: ¥13.627735 10: ¥12.856354 100: ¥12.128636 500: ¥11.442110 查看所有的价格 -	最小起订量: 1 最小包装量: 1	11 Weeks	Tin	通孔		Nylon			未说明	Brass						Bulk	2002		e3	yes	活跃		Solder	EAR99	公母针	22	105°C	-40°C	Natural		2		MINI-FIT JR, LOW PROFILE	8536.69.40.30	Ramp	600V	NO	NO	NO	NO		NO	GENERAL PURPOSE	4.2mm	22	直角							6A			ONE	UL, CSA		COMMERCIAL		4.191 mm			2	4.2mm			RECTANGULAR		0.394 inch	Male				NO		6A		SQ PIN-SKT	10mOhm	1GOhm		RECEPTACLE	Compliant			极化外壳	1500VAC V	5.5118 mm	30 Cycles			RECTANGULAR		3.1136 N	低卤素		2	1.5kV	Non-compliant				10mm	57.4mm	12.8mm								无SVHC	符合RoHS标准	UL94 V-2
5023520610	Molex	数据表	1141 In Stock	1: ¥14.489161 10: ¥13.669017 100: ¥12.895299 500: ¥12.165376 查看所有的价格 -	最小起订量: 1 最小包装量: 1	17 Weeks	Surface Mount, Right Angle		Square				LOCKING	装配钉	Gold	Copper Alloy	Polyamide (PA), Nylon	-40°C				Tape & Reel (TR)	2015	DuraClik 502352			活跃	1 (Unlimited)	Solder	EAR99	Header	6				Automotive, Industrial				插销座						公母针					6				0.252 6.40mm	Board to Cable/Wire	All			0.079 2.00mm	Natural	ONE	UL		COMMERCIAL				Shrouded - 4 Wall	1				RECTANGULAR		0.252 inch						0.37 inch						0.079 inch					极化外壳	500VAC V		30 Cycles								1				Solder Retention										UL94 V-0			ROHS3 Compliant
44472-0654	Molex	数据表	3229 In Stock	1: ¥11.261707 10: ¥10.624252 100: ¥10.022878 500: ¥9.455547 查看所有的价格 -	最小起订量: 1 最小包装量: 1	Tin	通孔		Nylon			铜合金							Bulk			e3	yes			Solder	EAR99	公母针	6	105°C	-40°C	Natural		Male	MINI-FIT HCS		Ramp	600V	NO	NO	NO	NO		NO	GENERAL PURPOSE	4.2mm	6	Vertical							11A			ONE	UL, CSA		COMMERCIAL		4.191 mm			2	4.2mm			RECTANGULAR							NO	0.5 inch			SQ PIN-SKT	10mOhm	1GOhm		RECEPTACLE				极化外壳	1500VDC V	5.5118 mm	30 Cycles			RECTANGULAR					2		Non-compliant			4.2mm		13.8mm	9.6mm									符合RoHS标准	UL94 V-2	无铅