Creating contact pads for PCAD 45. E-books

On printed circuit boards simple (Simple.) I. sophisticated (COMPLEX) stacks contact pads I. transition holes (Via stacks.). The contact pad stack is a file that contains a description of the contact pad graphics in various layers of PP and the number of the photoplotter aperture.

Fig. 2.15. Project Technology Window

Stacks for shtyrevy conclusions (Dip.-Corps) components that have the same form of contact pads on all layers of PP, and stacks for components with planar conclusions (SMD.-Corps) having contact pads on one layer of PP form simple stacks. Components with planar conclusions are placed on layers Top. or Bottom (The graphics of the enclosures of these components are set on the same layers). Sophisticated stacks On different layers of PPs may have different geometric shapes. Stack first contact The component should differ (for example, a square) from other stacks of the same component.

To form (edit) stacks Completed command Options / Pad Style (Fig. 2.16). In the region of Current Style. At the beginning of work, there is usually only one stack of contact site - Default.. Highlight line Default.Click the button Copy. And in the window Pad Name. Enter the name of the new stack of the contact site (for example, dIP17) and press OK. In the region of Current Style. The name of the new contact site will appear. Similarly, you can sequentially enter the names (while the names!) Of all the necessary stacks.

In fig. 2.16 shows examples of stacks whose names reflect the shape and dimensions of contact sites:

Fig. 2.16. Stacks of contact pads

• dIP17 - Round platform with a diameter of 1.7 mm;
• DIP12 - Round platform with a diameter of 1.2 mm;
• plan2108. - planar platform of 2.1 x 0.8 mm;
• REC1212. - Square (rectangular) platform size 1.2 x 1.2 mm.

To create a component seating in the P-CAD Pattern Editor program in manual mode, use several functions of this program.

The Options / Configure command, set the metric measurement system and the required size of the Workspace Size (width - width and height - height, for example, 500x500 mm).

The Options / Grids command or by installing the cursor to the Grid Select cell (at the bottom of the program), install the grid steps. Always used a grid step equal to 0.1mm and there are no problem with the production of printed circuit boards. To attach the mouse cursor to the grid nodes, you can use the VIEW / Snap to Grid command.

The Options / Current Line command or by installing the cursor in the Line Width cell (at the bottom of the program), you can set the line thickness thickness.

The Options / Display command set the colors of objects located on various layers of the board. In principle, this feature used only in the PCB Editor itself.

In the P-CAD installed such structure of the board layers:

• Thor - conductors on the upper side of the board,
• Bottom - Conductors on the bottom of the board, - Top and Bottom layers are layers designed to install components.
• Board -Contour board,
• Top Mask - skate mask graphics on the top of the board,
• Bot Mask - Skiing mask graphics on the bottom of the board,
• Top Silk - silk screen on the upper side of the board (positional designations of components),
• Bot Silk - silk screen on the underside board,
• Top Paste - soldering schedules on the upper side of the board,
• Bot Paste - brake soldering on the bottom side of the board.

Figure 1. Option / Pad Styles menu window.

Command Option / Pad Styles, press the COPY button (new type of contact pad), enter the name of the created contact site (the input name must reflect some parameters of the stack created, for example, the name P: REW25H15D0 shows that the platform is planar and has a view of a rectangle with dimensions 2.5 mm x 1.5 mm and is only on the Top layer, since the diameter of the hole is 0. This operation is worth repeating as many times as many different contact sites are involved in creating your landing place.

On printed circuit boards, you can place simple (simple) and complex (complex,) stacks of contact pads. Stacks for pinchings (DIP-enclosures) of components that have the same form of contact pads on all layers of PP, and stacks for components with planar conclusions (SMD enclosures) having contact pads on a single PP layer forming simple stacks. Components with planar conclusions are placed on the layers of the Thor or Bottom. Complicated stacks on various PP layers can have a different geometric shape. The stack of the first component contact is desirable should be different (for example, a square or a rectangle) from other stacks of the same component. To edit the contact pads, the Options / Pad Style command is performed (Fig. 3). After selecting the stack name and pressing the MODIFY button, open the edit menu of simple contact pads, respectively, when you click on the Modify button (Complex) - for complex.

Figure 2. Edit window of simple stacks.

In the round area, the type of contact pad is selected:

• * THRU - contact pad for pin output;
• * Thor - contact pad for planar output from the installation of the component on PP;
• * Bottom - contact pad for planar output from the component mounting.

The Plane Connection area indicates the type of contact sites when they are connected to solid metallization layers:

• * Thermal - contact pad with thermal barrier;
• * Direct is a solid contact pad, directly connected to a layer of metallization.

The SHAPE window is installed in the SHAPE window:

• * Ellipse - elliptical (circle);
• * OVAL - oval;
• * Rectangle - rectangular;
• * Rounded Rectangle -Fromed with rounded corners;
• * Target - crossroads for drilling;
• * Mounting Hole - fastening (mounting) hole.

The editing window of complex contact sites is shown in Figure 3.

In the Layers window, sequentially indicate the names of the layers on which the contact pads of the stack will be placed. Layer names appear when the list of layers is disclosed in the Layer Pad Definition area, the desired layer is selected from the list and adds to the Layers field when you click on the Add button. In the Shape, Widht and Height windows, the Pad Definition area indicate the form of the contact site on the selected layer, its width and height, respectively.

The Shape list shows thirteen options for the forms of contact pads:

• * POLIGON - contact pad, determined by the polygon;
• * Thermal 2 SPOKE - contact pad with two thermal barriers;
• * Thermal 2 SPOKE / 90 - contact pad with two thermal barriers deployed at 90 °;
• * THERMAL 4 SPOKE - contact pad with four-road barriers;
• * THERMAL 4 SPOKE / 45 - contact pad with four thermal barriers deployed by 45 °;
• * Direct Connect - contact pad with direct compound with a solid layer of metallization.
• * Other options are for contact pads with simple forms.

When choosing a contact site in the form of a thermal barrier in the appearing Outer Dia / Inner Dia windows, the values \u200b\u200bof the external and internal diameters of the site are introduced. The Spoke Width window sets the width of the thermal barrier.

In the Hole area in the Diameter window, the diameter of the metallized / non-metallic (turned on / off the Plated checkbox) of the hole connecting the PP layers is set. Displays the center of the hole relative to the photocopyard aperture center (horizontally - x offset and vertically - y offset) is determined by the equipment used for the manufacture of photoshop.

After installing the parameters, the MODIFY button is pressed for each contact site.

All formed stacks of contact pads can be placed on the work field using the PLACE / PAD command. This placement of the contact pads of stacks is made to create a seating area for installing the component in order to follow it to the library or in a separate file (PAT extension).

When working with a modern elementary base, it is often necessary to create contact pads of non-standard form, which are not presented in the list of standard geometries (ovals, rectangles, etc.).

To create complex contact pads, it is necessary to draw a polygon of the appropriate form (it should be remembered that there is a limit on the number of vertices of the polygon in 255). Next, you need to set the reference point (Refpoint), which will be

"Center" created by KP. A hole will be installed in this "center" of the contact site if this contact pad is supposed to be used for pin items. In addition, when installing the contact site on the blank of the element housing, the movement and rotation of the KP will occur relative to this "center". Next, the billet of the KP in the form of a polygon and the point when knage is allocated and the formation of a new style of KP is based on (Fig. 1).

To do this, the Option / Pad Style command is selected. It is worth noting that only the complex type of KP (COMPLEX) can be used to create a CP of an arbitrary form, which allows you to specify various "heel" geometry on different layers. When creating a CP type COMPLEX, it should be remembered that such a CP cannot be converted to a simple type (Simple) that contains the one-type "heel" geometry on each layer.

In the complex editing window that opens (the Modify Complex command) from the Layer command, the required layer is selected, in this case the upper signal layer is Top, and the SHAPE section indicates the required geometry - Polygon. The MODIFY button opens the parameter settings dialog box, which selects the fourth paragraph Selected Polygon (highlighted polygon).

To create a planar KP (a complex form, as a rule, is used only in this case), you must specify the zero decadeter of the hole (Hole parameter), and on all other signal and screen layers, select the NO Connect option (this will allow you to remove "heel" with All layers, except the top).

If the fee is assumed to cover the protective mask and use the solder solder, then in addition to the signaling layers, it is necessary to prepare for each side of the board for two additional photosos: mask (Mask) and screen (PASTE). Both of these layers are inverse, that is, the elements located on these layers will become cuts in a protective mask on the board and stencil. The drawing of these layers is formed automatically on the basis of technological parameters, in the general case in the P_CAD PCB Topology Editor. To do this, in the Option / Configure / Manufacturing section, the following parameters are set:

1. SOLDER MASK SWELL - the value of increasing the cutout in the mask layer relative to the size of the contact site.

2. Paste Mask Shrink - Reducing the value of the cutout in the stencil relative to the contact site.

Figure 2 shows an example of the formation of a mask and screen cutting, subject to the task of both parameters equal to 0.3 mm (from left to right: KP, mask cutout, screen cut). It should be noted that the specified 0.3 mm will be added (mask cutout) and removed (stencil cut) "in all directions". When forming cutouts in a mask and stencil, which coincide in the form with the contact site there is no need to make descriptions of their geometry. When using large contact sites, the effect of the drawing may occur, to eliminate which it is recommended not to solve the soldering paste on the entire surface of the KP, and the separation of it into several "portions".

As a rule, such requirements for non-standard solutions of soldering paste are described in detail in the technical documentation on the element base (indicating the drawing of the required cuts). Figure 3 is quite conditionally indicated an example of the formation of several cuts in a stencil above one contact site.

In this case, naturally, the automatic formation of screen cuts will not lead to the desired result, and they will have to be created manually. This task is solved in two stages. At the first stage, you must turn off the standard formation of the cutout on the screen layer. To do this, in the Shape section, the NO Connect parameter is selected for the Top Paste layer. Manual geometry selection (specifying what_libo parameter for the Top Paste layer in the KP styles editor) results in the options specified in the Option / Configure / Manufacturing section stop acting for this contact site. That is, instead of repetition, the KP form (with an increase in or decreased sizes), the generated cutout will have a geometry specified in the Shape section - in our case the cutout will not be at all.

At the second stage, a cutout or several cuts is formed. To do this, the Top Paste layer is manually posted standard graphic primitives in such a way that the desired "drawing" is obtained (for example, using a Polygon primitive).

This operation is performed, of course, at the stage of creating a seating in the component in the Pattern Editor enclosure editor. It should be noted that the contact pads made in the way, the CO hold information from two sources: the heel geometry indicated in the style used, and the graphic primitives located on the Top Paste layer of the housing (and not KP!). This circumstance leads to the fact that the subsequent use of this style will not allow to correctly form the desired contact pad without additional adjustments. These adjustments will be reduced to the following: above the contact pad to which this style will be applied, it is necessary to manually place the items corresponding to screen cuts. That is, for example, when creating a component body containing two identical contact pads, which requires the requirement of a portion separation of soldering paste, must be created as follows:

1. According to the algorithm described above, a KP style is created that does not contain standard screen cuts;

2. In the seating location is the first of two such KPs;

3. Manually formed the required cuts;

4. The second contact site of this type is set by the place pad, and the copy of the already installed KP with all the elements located manually on the Top Paste layer.

5. The second and subsequent CP installed by copying changes are changed manually or using the Utils / Renumbers command.