In the entire production process of modern PCB, kua riro te mangumangu tetahi o nga rauemi awhina tino nui i roto i te mahi hangahanga PCB o nga wheketere PCB. He waahi tino nui kei roto i nga rauemi tukanga PCB. Ko te angitu me te kore o te whakamahi waituhi ka pa ki nga whakaritenga hangarau katoa me nga tohu kounga o nga tuku PCB. Mo tenei take, ko nga kaihanga PCB he mea nui ki te mahi o nga waituhi. I tua atu i te pokey waituhi rongonui, ko te thixotropy hei mangumangu ka warewarehia e te tangata. Engari he mahi tino nui ki te paanga o te panui mata.

Kei raro nei ka tātari me te torotoro i te awe o te thixotropy i roto i te punaha PCB i runga i te mahi waituhi:

1. Mata

Ko te mata hiraka tetahi o nga mea tino nui i roto i te mahi tuhi mata. Ki te kore he mata, kaore e taea te kiia he panui mata. Ko te tuhi mata te wairua o te hangarau tuhi mata. Ko nga mata he tata katoa nga papanga hiraka (ko te tikanga kei reira ano nga papanga hiraka kore).

In the PCB industry, the most commonly used is the t-type net. s and hd type networks are generally not used except for individual special needs.

2. Waituhi

E pa ana ki te matū gelatinous tae e whakamahia ana mo nga papa kua taia. I te nuinga o te wa ka hangaia he kapia waihanga, he whakarewa wariu, he hinu me te whakakii, he whakamaroke, he whakangao me te wairewa. Ka karangahia te waituhi.

Torutoru. He maha nga waahanga hangarau nui o te waituhi PCB

Ahakoa he pai te kounga o te waituhi PCB, i roto i te kaupapa, kaore e taea te wehe atu i te huinga o nga waahanga nui o runga. Ko te kounga pai o te waituhi he whakaaturanga matawhānui o te pūtaiao, te ahunga whakamua me te tiaki taiao o te tauira. Ka whakaatuhia ki:

(1) Viscosity: poto mo te pokey hihiri. Ko te nuinga o te whakaatu ma te pokey, ara, te ahotea kutikuti o te rere wai wehea e te rōnaki tere i te ahunga o te paparanga rere, ko te wae o te ao ko Pa/sec (pa.s) ranei milliPascal/sec (mpa.s). I roto i te hanga PCB, e pa ana ki te rere o te waituhi i hangaia e nga mana o waho.

(2) Plasticity: I muri i te waituhi te deformed e te kaha o waho, te reira mau tonu ona āhuatanga i mua i deformation. Ko te kirihou o te waituhi he pai ki te whakapai ake i te tika o te tuhi;

(3) Thixotropic: (thixotropic) He gelatinous te waituhi ina waiho kia tu, ka huri te pokey ina pa. Ka kiia hoki ko te thixotropic me te sag resistance;

(4) Fluidity: (leveling) the extent to which the ink spreads around under the action of external force. Fluidity is the reciprocal of viscosity, and fluidity is related to the plasticity and thixotropy of the ink. The plasticity and thixotropy are large, the fluidity is large; the fluidity is large, the imprint is easy to expand. With low fluidity, it is prone to network formation, resulting in ink formation, which is also known as reticulation;

(5) Viscoelasticity: refers to the ability of the ink that is sheared and broken after the ink is scraped by the squeegee to rebound quickly. It is required that the ink deformation speed is fast and the ink rebounds quickly to be beneficial to printing;

(6) Te maroke: ko te puhoi o te whakamaroke o te waituhi i runga i te mata, ko te pai ake, me te tere ake i muri i te whakawhitinga o te waituhi ki te taputapu;

(7) Fineness: the size of pigment and solid material particles, PCB ink is generally less than 10μm, and the size of the fineness should be less than one-third of the mesh opening;

(8) Stringiness: Ka kohia te mangumangu ki te koko waituhi, ko te tohu e kore e pakaru te mangumangu penei i te hiraka ina totoro ka kiia ko te aho. He roa te kakawaea waituhi, a he maha nga kakawaea kei runga i te mata waituhi me te mata o te tuhi, ka paru te tïpako me te pereti ta, kaore e taea te tuhi;

(9) Te marama me te huna i te mana o te mangumangu: Mo nga waituhi PCB, he maha nga whakaritenga e tukuna ana mo te maamaa me te huna i te mana o te mangumangu kia rite ki nga whakamahinga rereke me nga whakaritenga. Ko te tikanga, ko nga waituhi ara iahiko, nga waituhi whakahaere me nga waituhi ahua me kaha te huna. He ngawari ake te parenga solder.

(10) Te ātete matū o te mangumangu: He tino paerewa te waituhi PCB mo te waikawa, te alkali, te tote me te whakarewa kia rite ki nga kaupapa rereke;

(11) Physical resistance of the ink: PCB ink must meet external scratch resistance, thermal shock resistance, mechanical peel resistance, and meet various strict electrical performance requirements;

(12) Te haumaru me te tiaki i te taiao o te waituhi: Ko te waituhi PCB e hiahiatia ana kia iti te paitini, kia kore e hongi, kia haumaru, kia pai te taiao.

I runga ake kua whakarāpopotohia e matou nga ahuatanga taketake o nga waituhi PCB tekau ma rua. I roto ia ratou, i roto i te mahi tūturu o te tā mata, te raruraru o te pokey he tata ki te kaiwhakahaere. He mea tino nui te viscosity ki te maeneene o te mata hiraka. Na reira, i roto i nga tuhinga hangarau waituhi PCB me nga purongo qc, ka tino tohuhia te viscosity, e tohu ana i raro i nga ahuatanga me te ahua o te taputapu whakamatautau viscosity hei whakamahi. I roto i te tikanga o te mahi ta, mena he tiketike rawa te pokey waituhi, he uaua ki te whakaputa, a ka tino kopikopiko nga taha o nga whakairoiro. Hei whakapai ake i te paanga o te ta, ka taapirihia he angiangi kia tutuki ai nga whakaritenga. Engari ehara i te mea uaua ki te kitea i roto i te maha o nga keehi, kia whiwhi ai i te whakataunga pai (taumira), ahakoa he aha te viscosity e whakamahia ana e koe, kaore e taea te whakatutuki. He aha? Whai muri i nga rangahau hohonu, ka kitea e au ko te pokey waituhi tetahi take nui, engari ehara ko te mea anake. Tera ano tetahi take nui: thixotropy. E pa ana hoki ki te tika o te ta.

E wha. Thixotropy

Viscosity and thixotropy are two different physical concepts. It can be understood that thixotropy is a sign of changes in ink viscosity.

When the ink is at a certain constant temperature, assuming that the solvent in the ink does not evaporate quickly, the viscosity of the ink will not change at this time. The viscosity has nothing to do with time. The viscosity is not a variable, but a constant.

Ka tukuna te mangumangu ki te kaha o waho (te whakaoho), ka huri te pokey. I te wa e haere tonu ana te kaha, ka heke haere tonu te pokey, engari kare e taka mo ake tonu atu, ka mutu ina tae ki tetahi rohe. Ka ngaro te kaha o waho, i muri i etahi wa e tu ana, ka taea e te mangumangu te hoki ki te ahua taketake. Ka karangahia e matou tenei ahua o te taonga tinana whakahuri ka heke te pokey waituhi me te roanga o te wa i raro i te mahi a te kaha o waho, engari i muri i te ngaro o te kaha o waho, ka taea te hoki ki te pokey taketake hei thixotropy. Ko te Thixotropy he taurangi e pa ana ki te wa i raro i te mahi a te kaha o waho.

I raro i te mahi o te kaha o waho, te poto o te roanga o te kaha, me te tino heke o te viscosity, ka kiia e matou tenei waituhi he nui te thixotropy; engari, ki te kore e kitea te heke o te pokey, ka kiia he iti te thixotropy.

5. Reaction mechanism and control of ink thixotropy

What exactly is thixotropy? Why is the viscosity of the ink reduced under the action of external force, but the external force disappears, after a certain period of time, the original viscosity can be restored?

Hei whakatau mehemea kei te waituhi nga tikanga e tika ana mo te thixotropy, ko te tuatahi ko te kapia me te pokey, katahi ka whakakiia ki tetahi tauwehenga o te whakakii me nga matūriki poaka. I muri i te kapia, te whakakī, te poaka, te tāpiritanga, me ētahi atu, ka kuia, ka tukatukahia, ka tino rite te whakakotahitanga. He ranunga ratou. I te kore o te wera o waho, te hiko marama ultraviolet ranei, kei te noho hei roopu katote koretake. I raro i nga ahuatanga noa, ka whakaritea i runga i te raupapa na runga i te kukume tahi, e whakaatu ana i te ahua o te pokey teitei, engari kaore he tauhohenga matū ka puta. A, ka tukuna ki te kaha miihini o waho, ka pakaru te whakaritenga o mua, ka tapahia te mekameka kukume tahi, ka noho he ahua kino, e whakaatu ana ka heke iho te viscosity. Koinei te ahuatanga ka kite tatou i te mangumangu mai i te matotoru ki te kikokore. Ka taea e tatou te whakamahi i te raarangi kati e whai ake nei ka taea te whakahuri hei whakaatu i nga mahi katoa o te thixotropy.

It is not difficult to find that the amount of solids in the ink and the shape and size of the solids will determine the thixotropic properties of the ink. Of course, there is no thixotropy for liquids that are inherently very low in viscosity. However, in order to make it into a thixotropic ink, it is technically possible to add an auxiliary agent to change and increase the viscosity of the ink, making it thixotropic. This additive is called a thixotropic agent. Therefore, the thixotropy of the ink is controllable.

ono. Te tono whai kiko o te thixotropy

I roto i nga tono whaitake, ehara i te mea ko te nui o te thixotropy, ko te pai ake, ko te iti ake ranei te pai ake. Kati noa. Na ona ahuatanga thixotropic, he tino pai te waituhi mo te tukanga o te tuhi mata. He ngawari te mahi tuhi mata me te kore utu. I te wa o te panui mata waituhi, ka panaia te mangumangu i runga i te kupenga e te squeegee, ka puta te hurihuri me te kumete, ka heke iho te pokey o te mangumangu, he pai ki te kuhu waituhi. I muri i te taia o te waituhi ki runga i te papa PCB, na te mea kaore e taea te whakaora wawe i te pokey, he waahi tika kia pai te rere o te waituhi, a ka whakahokia mai te toenga, ka pai nga tapa o te mata o nga whakairoiro. papatahi.