Unhu hwegungano reSMT (Surface Mount Technology) yakanangana nePCB padhi dhizaini, uye saizi reshiyo yemapadhi yakakosha. Kana iyo PCB pad dhizaini yakaringana, misalignment diki panguva yekuiswa inogona kugadziriswa panguva yereflow soldering process (inozivikanwa sekuzvigadzirisa kana kuzvigadzirisa). Kune rimwe divi, kana iyo PCB pad dhizaini isiriyo, kunyangwe kuiswa chaiko kunogona kukonzera kusarongeka kwechikamu, solder mabhiriji, uye kumwe kukanganiswa kwekutengesa mushure mekuyerera kwekutengesa.
Basic Nheyo dzePCB Pad Dhizaini
Zvichienderana nekuongororwa kweakasiyana echikamu majoini majoini, kuve nechokwadi chekuvimbika kwemajoini ekutengesa, iyo PCB pad dhizaini inofanirwa kutarisa pane zvinotevera zvinhu zvakakosha:
- Symmetry: Mapedhi kumativi ese ari maviri anofanirwa kunge ari symmetric kuti ive nechokwadi chekuenzana kwekunyungudusa kwesolder's surface tension.
- Pad Spacing: Ita shuwa kupindirana kwakaringana pakati pechikamu chinotungamira kana mapini nemapadhi. Mapadhi ari kure zvakanyanya kana ari padhuze pamwe chete anogona kukonzera kukanganisa kwekutengesa.
- Kusara Pad Size: Saizi yasara mushure mechikamu chinotungamira kana pini inopindirana nepedhi inofanira kunge yakakwana kubvumira kuumbwa kweanovimbika solder joint.
- Pad Width: Iyo pad hupamhi inofanirwa kuwanzoenderana nehupamhi hwechikamu chinotungamira kana pini.
Solderability Kukanganisa Kunokonzerwa nePad Size
Zvisingaenderani Pad Saizi
Mapedhi saizi anofanirwa kuenderana, uye kureba kwawo kunofanirwa kunge kuri mukati mechikamu chakakodzera. Mapedhi akapfupika kana akareba anogona kukonzera "tombstoneing" (kusimuka) chiitiko. Kusawirirana kwepadhi saizi kana kusaenzana kudhonza masimba kunogona zvakare kutungamira kune chikamu chetombstone.
Pad Width Yakanyanya Kuwanda Kuenzaniswa neChikamu Inotungamira
Iyo pad dhizaini haifanirwe kuve yakafara zvakanyanya kana ichienzaniswa nechikamu. Pedhi yakafara mamirimita maviri yakafara pane chikamu chinotungamira inokwana. Kana iyo padhi yakafara zvakanyanya, inogona kutungamira mukutamiswa kwechikamu, kutonhora solder majoini, kana kusakwana kuvharika kwe solder padhi.
Pad Width Yakanyanya Kutetepa Kuenzaniswa neComponent Leads
Kana hupamhi hwepadhi hwakatetepa kupfuura chikamu chinotungamira, pachave nekusakwana kwekuonana nzvimbo pakati pechikamu chinotungamira uye padhi panguva yekuiswa kweSMT. Izvi zvinogona kuita kuti chikamu chacho chirereke kana kuputika panguva yekugadzira.
Pad Kureba Kwakareba Kuenzaniswa neChikamu Inotungamira
Mapadhi haafanire kunge akareba zvakanyanya kana achienzaniswa nechikamu chinotungamira. Kana iyo padhi ikawedzera kureba, yakawandisa solder paste inoyerera panguva yereflow soldering inogona kukwevera chikamu kune rimwe divi, zvichikonzera kusarongeka.
Pad Spacing Yakanyanya Kuvhara
Nyaya yekupfupika-kutenderera nekuda kwekusakwana pad spacing inowanzoitika muIC pads. Nekudaro, kuparadzaniswa kwemukati kwemapedhi kune zvimwe zvikamu hazvifanirwe kunge zvakapfupika pane inotungamira nzvimbo yechikamu. Kana nzvimbo yacho yanyanya kutetepa, inogona kuguma nedunhu pfupi.
(pic-PCB Pad Dhizaini-4)
Pad Pin Width Yakanyanya Diki
Mukuiswa kweSMT, kana hupamhi hwepadhi hwakanyanya kudiki, zvinogona kutungamira mukusarongeka. Semuenzaniso, kana imwe padhi iri diki kana mamwe madiki pane mamwe, anogona kukonzera kusakwana kana kusakwana solder pane iyo padhi, zvichikonzera kusawirirana uye kutamiswa kwechikamu.
Mhosva Yechokwadi Yediki Padhi Inokonzeresa Chikamu Kusarongeka
Material Pad Saizi Haienderane nePCB Packaging Saizi
Dambudziko Tsananguro: Munguva yekugadzirwa kweSMT, mushure mekugadzirisazve kutengesa, zvakaonekwa kuti inductor yakanga yachinja nzvimbo. Pakuferefetwa, zvakaonekwa kuti saizi yepadhi yezvinhu (3.31mm) haina kufanana nePCB pad size (2.51.6mm), zvichiita kuti zvinhu zviome mushure mekutengesa.
Impact: Kusapindirana kwakakonzera kusabatana zvakanaka kwemagetsi, zvichikanganisa kushanda kwechigadzirwa. Muzviitiko zvakakomba, zvakakonzera kuti chigadzirwa chitadze kutanga.
Imwe Ngozi: Kana zvisingaite kutenga zvikamu zvine mapedhi anoenderana saizi inosanganawo neinodiwa inductance uye ikozvino kushivirira kwedunhu, pane njodzi yekuda kugadzirisa PCB dhizaini.
Chip Standard Package Pad Inspection
Kune chip standard package soldering kuvimbika cheki, zvinhu zvitatu zvakakosha zvinofanirwa kutariswa:
- Pad Length
- Pad Width
- Pad-to-Pad Spacing
Izvi zvinhu zvitatu zvakakosha pakuona kuti chip inogona kuiswa zvakanaka uye kutengeswa panguva yeSMT process.
