Fatturi jaffettwaw issaldjar difetti in pcb

1. Il issaldjar ta ' ċirkwit bord toqob jaffettwa iwweldjar kwalità

Fqir issaldjar ta ' ċirkwit bord toqob se riżultat fl istann difetti, li jaffettwaw il-parametri ta komponenti fi iċ-ċirkwit 2c li jwassal għal instabbli konduzzjoni ta ' b'ħafna saffi bord komponenti u ġewwa wajers, u causing il sħiħ ċirkwit funzjoni għal falliment. L-hekk imsejħa weldability tirreferi għal il- proprjetà tal- metall wiċċ li jkun imxarrab billi imdewweb issaldjar , li ifisser li l-istann formoli a relattivament uniformi u kontinwu lixx adeżiv film on il - Metall wiċċ .

The main factors affecting the solderability of printed circuit boards are: (1) the composition of the solder and the properties of the soldered material. Solder is an important component in the chemical treatment process of welding, consisting of chemical materials containing flux. The commonly used low melting point eutectic metals are Sn-Pb or Sn-Pb-Ag. The impurity content should be controlled in a certain proportion to prevent the oxide generated by impurities from being dissolved by the flux. The function of solder is to help wet the surface of the circuit board by transferring heat and removing rust. Generally, white rosin and isopropanol solvents are used. (2) Welding temperature and surface cleanliness of the metal plate can also affect weldability. If the temperature is too high, the diffusion speed of the solder will accelerate. At this time, it has high activity, which will cause rapid oxidation of the circuit board and solder melting surface, resulting in welding defects. The surface of the circuit board will also be contaminated, which will affect solderability and cause defects, including solder beads, solder balls, open circuits, poor glossiness, etc.

2. Welding difetti ikkawżati minn warping

Iċ-ċirkwit bord u komponenti prodotti warping matul il iwweldjar proċess , li jirriżulta f' difetti bħal istann ġonot u qosra ċirkwiti dovuti għal stress deformazzjoni. Warping is spiss caused by temperatura żbilanċ bejn il-parti ta 'fuq u isfel partijiet ta' a ċirkwit bord. Għal kbir PCBs, il piż ta ' il-bord innifsu jista' ukoll jikkawża warping. A normali apparat huwa dwar {{{{{{0}}}.5mm away minn a printed circuit board. If the device on the circuit board is large, as the circuit board cools down and returns to its normal shape, the sold joint will be under stress for a long time. If the device is raised by 0.1mm, it will be sufficient cause a false sold open circuit.

3. Id-disinn ta ' ċirkwit bordijiet jaffettwa iwweldjar kwalità

Fi termini ta' layout, when the circuit board size is too large, although welding is easier to control, the printed lines are longer, the impedance increases, the history increases, the noise resistance decreases, and the cost increases; Over time, the heat dissipation decreases, the heat dissipation decreases, making it difficult to control welding and prone to interference between adjacent lines, such as electromagnetic interference from circuit boards.

Għalhekk, it is necessary to optimize PCB board design: (1) shorten the wiring between high-frequency components and reduce EMI interferenza.

(2) Components with large weight (such as exceeding 20g) should be fixed with brackets and then welded.

(3) Tisħin elementi għandhom jikkunsidraw sħana dissipazzjoni kwistjonijiet, u termali sensittivi elementi għandhom jkunu jinżammu 'il bogħod minn sħana sorsi.

(4) L-arranġament ta' komponenti għandhom be as parallel as parallel as possible, li is mhux biss estetikament pjaċevoli iżda wkoll faċli għal weld, making it adattat for massa produzzjoni. The optimal rectangular design for the circuit board is 4:3. Do not make sudden changes in wire width to avoid discontinuity in wiring. When the circuit board is heated for a long time, copper foil is prone to expansion and detachment, therefore% 2c l- użu ta ' kbir żoni ta' ram fojl għandu jiġi evitat .