category.连接器_category.连接器品牌厂家，型号_价格_规格

类别是'category.矩形连接器 - 针座，公插针' (10000)

所有品牌

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	触点形状	房屋材料	安装选项1						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	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	入口保护	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	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	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	电路数量	最大额定电压（交流）	最大额定电流	偏振键	介电耐压	触点图案	插入力-最大值	拉坯力 - 最小值	符合辉光线	特征	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	RoHS状态	无铅
DF1B-16DP-2.5DS(01)	Hirose Electric Co Ltd	数据表	505 In Stock	1: ¥5.507940 10: ¥5.196170 100: ¥4.902048 500: ¥4.624573 查看所有的价格 -	最小起订量: 1 最小包装量: 1	10 Weeks	通孔	Through Hole, Right Angle	Square	Polyamide		Gold	0.177 4.50mm	Brass	Polyamide (PA), Nylon		-35°C~85°C	Bulk		DF1B	e3/e4	yes	活跃	1 (Unlimited)	Solder	EAR99	Header	16					2	Male	PACKAGING 100 PCS. IN A BAG	8536.69.40.40	Push-Pull	NO	NO	NO	NO	公母针	NO	GENERAL PURPOSE				直角			12.5mm	0.339 8.61mm	Board to Cable/Wire	All	unknown		0.098 2.50mm		ONE	UL, CSA	COMMERCIAL		0.098 (2.50mm)	0.130 3.30mm	Shrouded - 4 Wall	2	2.5mm			RECTANGULAR	MULTIPLE MATING PARTS AVAILABLE	0.339 inch	Female	94V-0	White		3A			30mOhm	1000000000Ohm	0.098 inch		250V	3A	极化外壳	650VAC V	50 Cycles		.417 N		键槽		22.5mm			8.00μin 0.203μm				UL94 V-0			符合RoHS标准	无铅
DF3-5P-2DSA(01)	Hirose Electric Co Ltd	数据表	N/A	1: ¥2.370600 10: ¥2.236416 100: ¥2.109825 500: ¥1.990402 查看所有的价格 -	最小起订量: 1 最小包装量: 1	10 Weeks	Gold	通孔	通孔	Square	Polyamide		Gold	0.122 3.10mm	Brass	Polyamide (PA), Nylon	100V	-55°C~105°C	Bulk	2008	DF3			活跃	1 (Unlimited)	Press-Fit, Solder		Header	5	85°C	-30°C	Black		1	Male			Push-Pull					公母针			3A	2mm		Straight			5mm	0.197 5.00mm	板对板或电缆	All		3A	0.079 2.00mm	Black						0.114 2.90mm	Shrouded - 4 Wall		2mm	5					Male		Black			0.299 7.60mm		30mOhm				100V	3A								5mm	12mm			8.00μin 0.203μm				UL94 V-0			符合RoHS标准	无铅
HIF3H-20P-2.54W	Hirose Electric Co Ltd	数据表	5 In Stock	-	最小起订量: 1 最小包装量: 1	10 Weeks		通孔	通孔	Square			Gold	0.276 7.00mm	Brass	Polybutylene Terephthalate (PBT)	300V	-55°C~85°C	Bulk		HIF3H	e3	yes	活跃	1 (Unlimited)	Wire Wrap	EAR99	Header	20					2			8536.69.40.40	Push-Pull	NO	NO	NO	NO	公母针	NO	GENERAL PURPOSE							0.177 4.50mm	板对板	All	unknown	3A	0.100 2.54mm	Black	ONE	UL	COMMERCIAL	1.039 inch	0.100 (2.54mm)	0.630 16.00mm	Unshrouded	2				RECTANGULAR	MULTIPLE MATING PARTS AVAILABLE			94V-0		0.177 inch		1.043 26.50mm		15mOhm	10000000Ohm	0.1 inch					650VAC V	500 Cycles									8.00μin 0.203μm	8.00μin 0.203μm	0.63 inch		UL94 V-0			符合RoHS标准
0878325016	Molex	数据表	28 In Stock	1: ¥18.260712 10: ¥17.227091 100: ¥16.251966 500: ¥15.332049 查看所有的价格 -	最小起订量: 1 最小包装量: 1	15 Weeks		表面贴装	Square			Gold	0.141 3.60mm	磷青铜	Polyamide (PA), Nylon, Glass Filled			Tube		Milli-Grid 87832		yes	活跃	1 (Unlimited)	Solder		Header	50				Automotive, General Purpose, Telecommunications	2				插销座					公母针										0.252 6.40mm	板对板或电缆	All			0.079 2.00mm	Black					0.079 (2.00mm)		Shrouded - 4 Wall				Tin																							Keying Slot, Pick and Place					15.0μin 0.38μm	74.8μin 1.90μm			UL94 V-0			ROHS3 Compliant
0015910068	Molex	数据表	19 In Stock	1: ¥2.861730 10: ¥2.699741 100: ¥2.546925 500: ¥2.402763 查看所有的价格 -	最小起订量: 1 最小包装量: 1	9 Weeks	表面贴装	表面贴装	Square			Gold	0.320 8.13mm	Copper Alloy	Liquid Crystal Polymer (LCP), Glass Filled			Tube		C-Grid 71308		yes	活跃	1 (Unlimited)	Solder		Header, Breakaway	6				Automotive, General Purpose, Lighting, Medical, Telecommunications	2	Male			Push-Pull	NO	NO	NO	NO	公母针	NO				6					0.090 2.29mm	板对板或电缆	All			0.100 2.54mm	Black					0.100 (2.54mm)		Unshrouded				Tin					94V-0																							15.0μin 0.38μm	74.8μin 1.90μm			UL94 V-0			ROHS3 Compliant
1510481609	Molex	数据表	3774 In Stock	1: ¥12.773255 10: ¥12.050237 100: ¥11.368153 500: ¥10.724667 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		Header	6				General Purpose, Industrial	2				插销座					公母针										0.630 16.00mm	Board to Cable/Wire	All			0.256 6.50mm	Red					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
DF19L-30P-1H(54)	Hirose Electric Co Ltd	数据表	N/A	-	最小起订量: 1 最小包装量: 1	10 Weeks	表面贴装	Board Edge, Cutout; Surface Mount, Right Angle		Polyamide		Gold	磷青铜	Polyamide (PA), Nylon	100V		-35°C~85°C	Tape & Reel (TR)	2008	DF19			活跃	1 (Unlimited)	Solder	EAR99	Receptacle	30					1			8536.69.40.40	摩擦锁					公母针										0.057 1.45mm	Board to Cable/Wire	All	unknown		0.039 1.00mm	Black							Shrouded - 3 Wall								Male								500MOhm											Solder Retention									UL94 V-0		无SVHC	符合RoHS标准
1053112202	Molex	数据表	3821 In Stock	1: ¥7.997612 10: ¥7.544914 100: ¥7.117848 500: ¥6.714947 查看所有的价格 -	最小起订量: 1 最小包装量: 1	9 Weeks		通孔	Square			Gold	Brass	Liquid Crystal Polymer (LCP)	250V		-40°C~105°C	Tray	2016	Nano-Fit 105311			活跃	不适用	Solder	EAR99	Header	2				Automotive, General Purpose, Industrial, Medical, Military, Telecommunications	1			8536.69.40.30	插销座					公母针										0.356 9.05mm	Board to Cable/Wire	All			0.098 2.50mm	Natural						0.126 3.20mm	Shrouded - 4 Wall				Tin																							Board Guide, Board Lock					15.0μin 0.38μm	59.0μin 1.50μm		21.30mm				ROHS3 Compliant
1053112203	Molex	数据表	72 In Stock	1: ¥6.203602 10: ¥5.852451 100: ¥5.521180 500: ¥5.208660 查看所有的价格 -	最小起订量: 1 最小包装量: 1	9 Weeks		通孔	Square			Gold	Brass	Liquid Crystal Polymer (LCP)	250V		-40°C~105°C	Tray	2016	Nano-Fit 105311			活跃	不适用	Solder	EAR99	Header	3				Automotive, General Purpose, Industrial, Medical, Military, Telecommunications	1				插销座					公母针										0.356 9.05mm	Board to Cable/Wire	All			0.098 2.50mm	Natural						0.126 3.20mm	Shrouded - 4 Wall				Tin																							Board Guide, Board Lock					15.0μin 0.38μm	59.0μin 1.50μm		21.30mm				ROHS3 Compliant
1053122206	Molex	数据表	766 In Stock	1: ¥13.995820 10: ¥13.203601 100: ¥12.456227 500: ¥11.751159 查看所有的价格 -	最小起订量: 1 最小包装量: 1	10 Weeks		通孔	Square			Gold	Brass	Liquid Crystal Polymer (LCP)	250V		-40°C~105°C	Tray	2016	Nano-Fit 105312			活跃	不适用	Solder	EAR99	Header	6				Automotive, General Purpose, Industrial, Medical, Military, Telecommunications	2				插销座					公母针										0.356 9.05mm	Board to Cable/Wire	All			0.098 2.50mm	Natural					0.098 (2.50mm)	0.126 3.20mm	Shrouded - 4 Wall				Tin																							板锁					15.0μin 0.38μm	59.0μin 1.50μm		21.30mm				ROHS3 Compliant
1722991110	Molex	数据表	1341 In Stock	1: ¥14.369699 10: ¥13.556324 100: ¥12.788982 500: ¥12.065074 查看所有的价格 -	最小起订量: 1 最小包装量: 1	7 Weeks	通孔	通孔	Square			Tin	Copper Alloy	Liquid Crystal Polymer (LCP)	400V		-40°C~105°C	Bulk	2015	Ultra-Fit 172299		yes	活跃	1 (Unlimited)	Solder	EAR99	Header	10				Automotive, General Purpose, Industrial, Lighting, Medical, Military, Telecommunications	2			8536.69.40.30	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																											Board Guide, Solder Retention					60.0μin 1.52μm	60.0μin 1.52μm		26.99mm	UL94 V-0			ROHS3 Compliant
1722992310	Molex	数据表	N/A	-	最小起订量: 1 最小包装量: 1	13 Weeks	通孔	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	10				Automotive, General Purpose, Industrial, Lighting, Medical, Military, Telecommunications	2			8536.69.40.30	插销座					公母针										0.465 11.80mm	Board to Cable/Wire	All			0.138 3.50mm	Natural					0.181 (4.60mm)	0.126 3.20mm	Shrouded - 4 Wall				Tin																							Board Guide, Solder Retention					30.0μin 0.76μm	60.0μin 1.52μm		26.99mm	UL94 V-0			ROHS3 Compliant
1722981310	Molex	数据表	601 In Stock	1: ¥33.413929 10: ¥31.522575 100: ¥29.738278 500: ¥28.054981 查看所有的价格 -	最小起订量: 1 最小包装量: 1	13 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	10				Automotive, General Purpose, Industrial, Lighting, Medical, Military, Telecommunications	2			8536.69.40.30	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																							电路板指南					30.0μin 0.76μm	60.0μin 1.52μm		26.99mm	UL94 V-0			ROHS3 Compliant
0878315035	Molex	数据表	19 In Stock	1: ¥52.580267 10: ¥49.604032 100: ¥46.796257 500: ¥44.147411 查看所有的价格 -	最小起订量: 1 最小包装量: 1	15 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	50	105°C	-55°C	Black	Automotive, General Purpose, Telecommunications	2				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)	0.138 3.50mm	Shrouded - 4 Wall			50	Tin						Black									50								Board Guide, Keying Slot		52.65mm			30.0μin 0.76μm	74.8μin 1.90μm			UL94 V-0	无		ROHS3 Compliant
1053111308	Molex	数据表	52 In Stock	1: ¥18.429295 10: ¥17.386130 100: ¥16.402007 500: ¥15.473589 查看所有的价格 -	最小起订量: 1 最小包装量: 1	9 Weeks		通孔	Square			Gold	Brass	Liquid Crystal Polymer (LCP)	250V		-40°C~105°C	Tray	2016	Nano-Fit 105311		yes	活跃	不适用	Solder		Header	8				Automotive, General Purpose, Industrial, Medical, Military, Telecommunications	1				插销座					公母针										0.356 9.05mm	Board to Cable/Wire	All			0.098 2.50mm	Black						0.126 3.20mm	Shrouded - 4 Wall				Tin																							Board Guide, Board Lock					30.0μin 0.76μm	59.0μin 1.50μm		21.30mm				ROHS3 Compliant
DF14-8P-1.25H(56)	Hirose Electric Co Ltd	数据表	N/A	-	最小起订量: 1 最小包装量: 1	10 Weeks		表面贴装	Surface Mount, Right Angle	Square			Gold	0.086 2.20mm	Brass	Polyamide (PA), Nylon	150V	-35°C~85°C	Tape & Reel (TR)		DF14	e4	yes	活跃	1 (Unlimited)	Solder	EAR99	Header	8					1	Male			Push-Pull	NO	NO	NO	NO	公母针	NO	GENERAL PURPOSE		8					0.098 2.50mm	Board to Cable/Wire	All		1A	0.049 1.25mm	Beige							Shrouded - 4 Wall				Tin-Copper		MULTIPLE MATING PARTS AVAILABLE			94V-0																		Board Guide, Solder Retention					3.90μin 0.099μm	39.4μin 1.00μm			UL94 V-0	无	Unknown	符合RoHS标准
1722982112	Molex	数据表	145 In Stock	1: ¥11.566136 10: ¥10.911446 100: ¥10.293816 500: ¥9.711152 查看所有的价格 -	最小起订量: 1 最小包装量: 1	13 Weeks	通孔	通孔	Square			Tin	Copper Alloy	Liquid Crystal Polymer (LCP)	400V		-40°C~105°C	Bulk	2015	Ultra-Fit 172298			活跃	1 (Unlimited)	Kinked Pin, Solder	EAR99	Header	12				Automotive, General Purpose, Industrial, Lighting, Medical, Military, Telecommunications	2			8536.69.40.30	插销座					公母针										0.465 11.80mm	Board to Cable/Wire	All			0.138 3.50mm	Natural					0.181 (4.60mm)	0.126 3.20mm	Shrouded - 4 Wall																											电路板指南					60.0μin 1.52μm	60.0μin 1.52μm		26.99mm	UL94 V-0			ROHS3 Compliant
HIF3E-20PA-2.54DSA(71)	Hirose Electric Co Ltd	数据表	186 In Stock	1: ¥23.253851 10: ¥21.937591 100: ¥20.695842 500: ¥19.524379 查看所有的价格 -	最小起订量: 1 最小包装量: 1	10 Weeks			通孔	Square		LOCKING	Gold	0.244 6.20mm	Brass	Polybutylene Terephthalate (PBT)	200V	-55°C~85°C	Tray		HIF3			活跃	1 (Unlimited)	Solder	EAR99	Header	20					2			8536.69.40.40	Push-Pull	NO	NO	NO	NO	公母针	NO	GENERAL PURPOSE							0.299 7.60mm	Board to Cable/Wire	All	unknown	1A	0.100 2.54mm	Black	ONE	UL	COMMERCIAL		0.100 (2.54mm)	0.114 2.90mm	Unshrouded	2			Tin	RECTANGULAR				94V-0				0.657 16.70mm		15mOhm	1000000000Ohm	0.1 inch															8.00μin 0.203μm	78.7μin 2.00μm			UL94 V-0			符合RoHS标准	无铅
0194280006	Molex	数据表	872 In Stock	1: ¥33.449881 10: ¥31.556491 100: ¥29.770276 500: ¥28.085166 查看所有的价格 -	最小起订量: 1 最小包装量: 1	13 Weeks	Panel, Through Hole	Panel Mount, Through Hole	Square		Tin	Copper Alloy	Polybutylene Terephthalate (PBT), Glass Filled				Tray		MX150L 19428		yes	活跃	1 (Unlimited)	Solder		Header					Automotive, General Purpose, Industrial	2				锁定坡道					公母针					Vertical	IP67 - Dust Tight, Waterproof			1.562 39.66mm	Board to Cable/Wire	All		18A	0.230 5.84mm	Black			600V		0.236 (6.00mm)	0.130 3.30mm	Shrouded - 4 Wall			4													1GOhm											Mounting Flange					100.0μin 2.54μm	100.0μin 2.54μm			UL94 V-0			ROHS3 Compliant
22-28-8244	Molex	数据表	N/A	-	最小起订量: 1 最小包装量: 1	10 Weeks	Gold	通孔	Thermoplastic		6.1976mm	Brass	250V				Bulk	2012		e3	yes	活跃		Solder	EAR99	公母针	24	75°C	0°C	Black		1			8536.69.40.40		NO	NO	NO	NO		NO	GENERAL PURPOSE	2.54mm	24	直角								4A			ONE	UL, CSA		COMMERCIAL				1				RECTANGULAR	MULTIPLE MATING PARTS AVAILABLE	0.098 inch	Male	94V-0					SQ PIN-SKT	20mOhm	50000000000Ohm		RECEPTACLE			极针位置		25 Cycles	250.25kV	RECTANGULAR	Non-compliant					30μin								符合RoHS标准	无铅
DF3-12P-2DS(01)	Hirose Electric Co Ltd	数据表	90 In Stock	-	最小起订量: 1 最小包装量: 1	10 Weeks		通孔	Through Hole, Right Angle	Square	Plastic		Gold	0.122 3.10mm	Brass	Polyamide (PA), Nylon	100V	-55°C~105°C	Bulk	2004	DF3	e4	yes	活跃	1 (Unlimited)	Press-Fit, Solder	EAR99	Header	12					1			8536.69.40.40	Push-Pull	NO	NO	NO	NO	公母针	NO	GENERAL PURPOSE			直角				0.197 5.00mm	板对板或电缆	All	unknown	3A	0.079 2.00mm		ONE	UL, CSA	COMMERCIAL			0.114 2.90mm	Shrouded - 4 Wall	1	2mm			RECTANGULAR	MULTIPLE MATING PARTS AVAILABLE		Male	94V-0	Black	0.283 inch	3A			30mOhm		0.079 inch				外壳侧	650VAC V	50 Cycles	4.3924 N	.3058 N							8.00μin 0.203μm				UL94 V-0			符合RoHS标准	无铅
TSM-103-01-S-SH-P-TR	Samtec Inc.	数据表	654 In Stock	1: ¥9.789159 10: ¥9.235054 100: ¥8.712320 500: ¥8.219164 查看所有的价格 -	最小起订量: 1 最小包装量: 1	3 Weeks		Surface Mount, Right Angle	Square	Polymer	LOCKING	Gold	0.230 5.84mm	磷青铜	Liquid Crystal Polymer (LCP)		-55°C~125°C	Tape & Reel (TR)	2011	TSM	e3		活跃		Solder		Header	3					1	Male			Push-Pull	NO	NO	NO	NO	公母针	NO	GENERAL PURPOSE			3	直角		2.54mm	10.92mm	0.120 3.05mm	板对板或电缆	All			0.100 2.54mm	Black	ONE	UL	COMMERCIAL				Unshrouded	1			Tin	RECTANGULAR														475V	7A							挑选和放置		7.62mm			30.0μin 0.76μm				UL94 V-0	无		ROHS3 Compliant	无铅
1053121310	Molex	数据表	286 In Stock	1: ¥29.100445 10: ¥27.453252 100: ¥25.899298 500: ¥24.433293 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	250V	Liquid Crystal Polymer (LCP)		-40°C~105°C	Tray	2016	Nano-Fit 105312			活跃	不适用	Solder	EAR99	Header	10				Automotive, General Purpose, Industrial, Medical, Military, Telecommunications	2			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																							板锁					30.0μin 0.76μm	59.0μin 1.50μm		21.30mm				ROHS3 Compliant
0015911203	Molex	数据表	6 In Stock	1: ¥44.911793 10: ¥42.369616 100: ¥39.971337 500: ¥37.708807 查看所有的价格 -	最小起订量: 1 最小包装量: 1	8 Weeks		表面贴装	Square			Gold	0.240 6.10mm	Copper Alloy	Liquid Crystal Polymer (LCP), Glass Filled			Tube		C-Grid 71308	e3	yes	活跃	1 (Unlimited)	Solder		Header, Breakaway	20				Automotive, General Purpose, Lighting, Medical, Telecommunications	2		STACKABLE		Push-Pull	NO	NO	NO	NO	公母针	NO				20					0.090 2.29mm	板对板或电缆	All			0.100 2.54mm	Black					0.100 (2.54mm)		Unshrouded				Tin					94V-0																		电路板指南					30.0μin 0.76μm	74.8μin 1.90μm			UL94 V-0			ROHS3 Compliant
B6B-EH-A(LF)(SN)	JST Sales America Inc.	数据表	21693 In Stock	1: ¥0.542469 10: ¥0.511763 100: ¥0.482796 500: ¥0.455468 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	Nylon		Tin	0.130 3.30mm	Brass	Polyamide (PA66), Nylon 6/6	250V	-25°C~85°C	Bulk	2010	EH	e3	yes	活跃	1 (Unlimited)	Press-Fit, Solder	EAR99	Header	6					1	Male	POLARIZED, TOP ENTRY, SHROUDED		摩擦锁	NO	NO	NO	NO	公母针	NO	GENERAL PURPOSE			Straight				0.236 6.00mm	Board to Cable/Wire	All		3A	0.098 2.50mm	Natural						0.126 3.20mm	Shrouded - 3 Wall		2.5mm							94V-0	White																		6mm	17.5mm	3.8mm					8.1mm	UL94 V-0		无SVHC	符合RoHS标准	无铅