PCB leanann modhanna sreangaithe ag feabhsú, agus féadann teicnící sreangaithe solúbtha fad na sreinge a laghdú agus níos mó spáis PCB a shaoradh. Tá sreangú traidisiúnta PCB teoranta ag comhordanáidí sreinge seasta agus easpa sreanga dronuilleach dronuilleach. Má dhéantar na teorainneacha seo a bhaint, féadfar cáilíocht na sreangaithe a fheabhsú go suntasach.

Let’s start with some terminology. Sainmhínímid sreangú dronuilleach Uillinn mar shreangú sreinge ag úsáid deighleoga dronuilleacha Uillinn agus raidianacha. Is cineál sreangaithe sreinge é, ach níl sé teoranta do dheighleoga líne Uillinn 90 céim agus 45 céim a úsáid. Topological wiring is wire wiring that does not adhere to grids and coordinates and does not use regular or irregular grids like shape-based wiring. Lig dúinn an téarma sreangú solúbtha a shainiú mar shreangú sreinge gan cruth seasta a chuireann ar chumas athríomh ríomh sreinge fíor-ama na féidearthachtaí claochlaithe seo a leanas a bhaint amach. Ní úsáidtear ach áirsí ó chonstaicí agus a gcuid tadhlaí coitianta chun cruth na líne a fhoirmiú. (Obstacles include pins, copper foil, forbidden areas, holes and other objects) part of the circuit of two PCB models. Ritheann na sreanga glasa agus dearga ar shraitheanna éagsúla den tsamhail PCB. The blue circles are the perforations. The red element is highlighted. There are also some red round pins. Use only line segments and models with an Angle of 90 degrees between them. Is samhail PCB é Figiúr 1B a úsáideann áirsí agus uillinneacha treallach. Wiring at any Angle may seem strange, but it does have many advantages. The way it is wired is very similar to how engineers wired it by hand half a century ago. Taispeánann sé fíor-PCB a d’fhorbair cuideachta Meiriceánach darb ainm Digibarn i 1972 le haghaidh sreangú láimhe iomlán. This is a PCB board based on Intel8008 computer. Tá an sreangú dronuilleach Uillinn a thaispeántar i bhFíor 2 cosúil i ndáiríre. Why would they use arbitrary Angle wiring? Toisc go bhfuil go leor buntáistí ag baint leis an gcineál seo sreangaithe. Arbitrary Angle wiring has many advantages. Ar dtús, mura n-úsáidtear na huillinneacha idir deighleoga líne sábhálann sé spás PCB (glacann polagáin níos mó spáis ná tadhlaithe i gcónaí). Traditional automatic cablers can place only three wires between adjacent components (see left and center in Figure 3). Mar sin féin, nuair a dhéantar sreangú ar aon Uillinn, tá go leor spáis ann chun 4 shreang a leagan ar an gcosán céanna gan sárú a dhéanamh ar sheiceáil rialacha dearaidh (DRC). Cuir i gcás go bhfuil sliseanna mód dearfach againn agus go dteastaíonn uainn na bioráin sliseanna a nascadh le dhá bhiorán eile. Using only 90 degrees takes up a lot of space. Trí shreangú dronuilleach Uillinn a úsáid is féidir an fad idir an sliseanna agus na bioráin eile a ghiorrú, agus an lorg a laghdú. In this case, the area was reduced from 30 square centimeters to 23 square centimeters. Rotating the chip at any Angle can also provide better results. In this case, the area was reduced from 23 square centimeters to 10 square centimeters. It shows a real PCB. Arbitrary Angle wiring with rotating chip function is the only wiring method for this circuit board. Ní amháin gur teoiric é seo, ach réiteach praiticiúil freisin (uaireanta an t-aon réiteach is féidir a dhéanamh). Shows an example of a simple PCB. Cé gur grianghraif den PCB iarbhír iad torthaí cáblaithe topology, cé gur torthaí uathoibríocha cáblaithe atá bunaithe ar an gcruth is fearr. An automatic cabler based on optimal shape cannot do this because the components are rotated at arbitrary angles. Teastaíonn níos mó achair uait, agus mura rothlaíonn tú na comhpháirteanna, caithfear an gléas a dhéanamh níos mó. Layout performance would be greatly improved without parallel segments, which are often a source of crosstalk. The level of crosstalk increases linearly as the length of parallel wires increases. As the spacing between parallel wires increases, crosstalk decreases quadratic. Let’s set the level of crosstalk produced by two parallel 1mm wires spaced d to e. Má tá Uillinn idir na deighleoga sreinge, ansin de réir mar a mhéadaíonn an Uillinn seo, laghdóidh leibhéal na crosstalk. The crosstalk does not depend on the length of the wire, but only on the Angle value: where α represents the Angle between the wire segments. Smaoinigh ar na trí mhodh sreangaithe seo a leanas. On the left side of Figure 8 (90 degree layout), there is the maximum wire length and the maximum emi value due to parallel line segments. In the middle of Figure 8 (45 degree layout), the wire length and emi values are reduced. On the right-hand side (at any Angle), the wire length is shortest and there are no parallel wire segments, so the interference value is negligible. So arbitrary Angle wiring helps to reduce the total wire length and significantly reduce electromagnetic interference. You also remember the effect on signal delay (conductors should not be parallel and should not be perpendicular to the PCB fiberglass). Advantages of flexible wiring Manual and automatic movement of components does not destroy the wiring in flexible wiring. Ríomhann an cábla go huathoibríoch an cruth is fearr is féidir ar an sreang (agus an t-imréiteach sábháilteachta riachtanach á chur san áireamh). Mar sin is féidir le cáblú solúbtha an t-am a theastaíonn chun an topology a chur in eagar go mór, ag tacú go deas le hathmhúnlú iolrach chun srianta a chomhlíonadh. Taispeánann sé seo dearadh PCB a ghluaiseann trí phoill agus pointí brainse. Le linn gluaiseachta uathoibríoch, déantar pointí brainse sreinge agus trípholl a choigeartú sa suíomh is fearr. In most computer-aided design (CAD) systems, the wiring interconnection problem is reduced to the problem of sequentially finding paths between pairs of points in a maze of pads, forbidden areas, and laid wires. Nuair a aimsítear cosán, socraítear é agus éiríonn sé mar chuid den chathair ghríobháin. Is é an míbhuntáiste a bhaineann le sreangú seicheamhach ná go bhféadfadh toradh na sreangaithe a bheith ag brath ar an ordú sreangaithe. Nuair nach bhfuil cáilíocht thoipeolaíoch fós foirfe, tarlaíonn an fhadhb “dul i bhfostú” i gceantair bheaga áitiúla. But no matter which wire you rewire, it’s not going to improve the quality of the wiring. This is a serious problem in all CAD systems using sequential optimization. This is where the bending elimination process is useful. Tagraíonn lúbadh sreinge don fheiniméan nach mór do shreang i líonra amháin siúl timpeall ar réad ar líonra eile chun réad a rochtain. Rewiring a wire will not correct this. Taispeántar sampla de lúbadh. A lit red wire travels around a pin in the other network, and an unlit red wire connects to this pin. Taispeántar torthaí uathoibríoch próiseála. In the second case (on another layer), a lighted green wire is automatically rewired by changing the wiring layer (from green to red). Eliminate wire bending by automatically optimizing wire shape (approximate arcs with line segments just to show any Angle examples without arcs). (top) original design, (bottom) after eliminating bending design. Tarraingítear aird ar shreanga lúbtha dearga. I gcrann Steiner, caithfear gach líne a nascadh mar dheighleoga le rinn (críochphointí agus breisithe). Ag barr gach rinn nua, caithfidh trí dheighleog teacht le chéile agus ní gá go dtiocfadh deireadh le níos mó ná trí mhír. The Angle between the line segments that converge to the vertex shall not be less than 120 degrees. Níl sé an-deacair Steiner a thógáil leis na hairíonna coinníollach leordhóthanacha seo, ach ní gá go bhfuil sé íosta. Gray Steiner trees are not optimal, but black Steiner trees are. I ndearadh cumarsáide praiticiúil, caithfear constaicí éagsúla a mheas. Cuireann siad teorainn leis an gcumas crainn íosta a thógáil ag úsáid halgartaim agus crainn Steiner ag úsáid modhanna geoiméadracha. The obstacles are shown in gray and we recommend starting at any end vertex. If there is more than one adjacent terminating vertex, you should choose one that allows you to continue using the second vertex. It depends on the Angle. Is é an príomh-mheicníocht anseo algartam fórsa-bhunaithe a ríomhann na fórsaí atá ag gníomhú ar na rinní nua agus a ghluaiseann arís agus arís eile go pointe cothromaíochta (braitheann méid agus treo na bhfórsaí ar na sreanga ag na pointí brainse cóngaracha). Má tá an Uillinn idir péire deighleog líne atá ceangailte le rinn (foirceann nó suimiú) níos lú ná 120 céim, is féidir pointe brainse a chur leis, agus ansin is féidir algartam meicniúil a úsáid chun suíomh an rinn a bharrfheabhsú. It’s worth noting that simply sorting all angles in descending order and adding new vertices in that order doesn’t work, and the result is worse. After adding a new node, you should check the minimum of a subnet consisting of four pins:

1. If a vertex is added to the vicinity of another newly added vertex, check for the smallest four-pin network.

2. If the four-pin network is not minimal, select a pair of “diagonal” (belonging to the quadrilateral diagonal) endpoints or virtual terminal nodes (virtual terminal nodes – wire bends).

3. The line segment that connects the endpoint (virtual endpoint) to the nearest new vertex is replaced by the line segment that connects the endpoint (virtual endpoint) to the distant new vertex.

4. Use mechanical algorithms to optimize vertex positions.

This method does not guarantee to build the smallest network, but compared with other methods, it can achieve the smallest network length without grazing. Ligeann sé freisin ceantair ina bhfuil cosc ​​ar naisc críochphointe, agus inar féidir líon na nóid críochphointe a bheith treallach.

Flexible wiring at any Angle has some other interesting advantages. For example, if you can automatically move many objects with the help of automatic real-time wire shape recalculation, you can create parallel serpentine lines. This cabling method makes better use of space, minimizes the number of iterations, and allows for flexible use of tolerances. If there are two serpentine lines interlaced with each other, the automatic cabler will reduce the length of one or both, depending on rule priority.

Consider the wiring of BGA components. In the traditional peripheral-to-center approach, the number of channels to the periphery is reduced by 8 with each successive layer (due to a reduction in perimeter). For example, a 28x28mm component with 784 pins requires 10 layers. Tá sreangú éalaithe ag cuid de na sraitheanna sa léaráid. Taispeánann Figiúr 16 an ceathrú cuid de BGA. Ag an am céanna, agus an modh sreangaithe “lár go forimeallach” á úsáid agat, ní athraíonn líon na gcainéal a theastaíonn chun imeacht chuig an imeall ó chiseal go ciseal. Laghdóidh sé seo go mór líon na sraitheanna. Maidir le méid comhpháirte 28x28mm, is leor 7 gciseal. Maidir le comhpháirteanna níos mó, is bua-bua é. Figure 17 shows a quarter of the BGA. An example of BGA wiring is shown. When using the “center to periphery” cabling approach, we can complete the cabling of all networks. Is féidir le cáblaire uathoibríoch topology Uillinn Eadrána é seo a dhéanamh. Traditional automatic cablers cannot route this example. Shows an example of a real PCB where the engineer reduced the number of signal layers from 6 to 4 (compared to the specification). In addition, it took engineers only half a day to complete the wiring of the PCB.